The aim of the Teagasc Animal and Grassland Research & Innovation Programme is to increase the profitability, competitiveness and sustainability of Irish livestock production through research and innovation.

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  • Effect of feed allowance at pasture on the lying behaviour of dairy cows

    O'Driscoll, Keelin; Lewis, Eva; Kennedy, Emer (Elsevier, 2019-02-10)
    In temperate climates where cows are primarily managed at pasture shortages of grass could result in nutritional deficits for the cow and may have a variety of behavioural consequences. Lying behaviour is one of the most researched aspects of dairy cow behaviour, and can provide insights into cow welfare and physiological state. This study investigated the effect of daily herbage allowance (DHA) on the lying behaviour of dairy cow during early lactation. Ninety-six cows were randomly assigned to one of eight treatments in a 2 × 4 factorial design; experimental duration (2 week (2 W) or 6 week (6 W)), and nutritional levels (DHA) (60%, 80%, 100% or 120% of intake capacity). Cows were assigned to treatment at 28 ± 8.4 days in milk, and lying behaviour of cows in the 6 W treatments recorded using modified voltage data loggers on 4 occasions; the week prior to the start of the experiment, during week 3 (MID), and week 6 (LATE), and 7 weeks after the study concluded (POST), when the cows were all returned to a feed allowance of 100% intake capacity. Although there was an effect of treatment on daily lying time (P < 0.01), with the 60% cows spending less time lying than the 120% (P < 0.01), cows in all treatments spent at least 9 h lying per day throughout the experiment. Daily lying time increased as the grazing season progressed (P < 0.001). Feed allowance affected both lying bout duration (P < 0.01) and number (P < 0.05), with cows on the highest feed allowance having the highest values for both. There was an effect of feed allowance on the time that cows first lay down after both morning and afternoon milking (P < 0.001), with a similar pattern for both times; the lower the feed allowance, the longer it took. During the POST period, this pattern was no longer evident in the afternoon, but still present in the morning. None of the treatments imposed resulted in daily lying times lower than those reported in other studies at pasture. However, the significant differences in patterns of lying during the day could be reflective of satiety level; the patterns of lying in cows with a low feed allowance compared to those with an allowance aligned with intake capacity are in agreement with previous research. Herd level recording of lying behaviour, relative to time since milking and/or fresh feed allocation, has potential for use as an animal welfare indicator for cows at pasture.
  • Evaluation of alternative strategies to treat anoestrous dairy cows and implications for reproductive performance in pasture-based seasonal calving herds: A pilot study

    Rojas Canadas, E.; Gobikrushanth, M.; Fernandez, P.; Kenneally, J.; Lonergan, P.; Butler, Stephen T.; Department of Agriculture, Food and the Marine; 13S528 (Elsevier, 2019-01-12)
    The objective of the present study was to assess the effects on ovulation and reproductive performance of a single injection of either GnRH or hCG applied 9 days before the start of the seasonal breeding period in anovulatory anoestrus cows compared with a 7-day progesterone-Ovsynch protocol. The study was conducted on four grass-based seasonal calving dairy herds in Ireland. The total number of cows in the herds was 2112, of which 488 were diagnosed as anoestrus based on absence of behavioural oestrus during a 30 day period. Ovarian structures and the uterus were examined by transrectal ultrasound on all 488 presumptive anestrus cows 9 days before mating start date (MSD). The number of corpora lutea (CL), number of large follicles (≥10 mm) and uterine reproductive tract score were recorded. Only cows that had no CL, ultrasound reproductive tract score ≤2 and were ≥30 days in milk (DIM) were enrolled in the study (n = 214). Cows were blocked by parity, DIM and body condition score and randomly assigned to one of four treatments: i.m. injection of gonadotropin releasing hormone analogue [GnRH; (n = 57)], i.m. injection of human chorionic gonadotropin [hCG; (n = 48)], 7-day Progesterone-Ovsynch protocol [P4OV; (n = 60)] and Control (no hormonal intervention, n = 49). A second ultrasound examination was performed 7 days after treatment to determine ovulatory response. There was a treatment effect on ovulation rate (P < 0.0001), whereby Control cows had a lesser ovulation rate compared with GnRH-, hCG- and P4OV-treated cows. Submission rate during the first 21 days of the breeding period [SR21; (P = 0.74)], pregnant to first service [P/AI1; (P = 0.24)], pregnant within 42 days after the onset of breeding [P42; (P = 0.73)], and pregnant within 84 days after the onset of breeding were not affected by treatment. A tendency was observed (P = 0.07) for greater likelihood of pregnancy within 21 days after the onset of breeding (P21) for P4OV and Control cows compared with GnRH- and hCG-treated cows. GnRH- and hCG-treated cows tended (P = 0.10) to have greater P/AI1 when first service events occurred after day 21 of the breeding period compared with Control cows. P4OV cows had shorter MSD to first service interval (P = 0.0001) and shorter MSD to conception interval (P = 0.02) compared with Control, GnRH- and hCG-treated cows. In conclusion, treatment of anestrous cows with GnRH or hCG resulted in an increase in ovulation rate compared with untreated Control cows, but did not improve reproductive performance during the first 21 days of the breeding season. The best reproductive performance results were obtained with the P4OV treatment, but this treatment has the greatest cost, and has the greatest number of interventions. The observation of good P/AI1 in hCG- and GnRH- treated cows when the first insemination occurred later than day 21 after MSD warrants further investigation, and suggests that these interventions should be applied earlier than 9 days before the farm MSD.
  • Systematic review and meta-analysis of the effect of feed enzymes on growth and nutrient digestibility in grow-finisher pigs: Effect of enzyme type and cereal source

    Torres-Pitarch, Alberto; Manzanilla, Edgar G; Gardiner, Gillian E.; O'Doherty, John V.; Lawlor, Peadar G; Teagasc; European Union’s Seventh Framework Programme; Teagasc Walsh Fellowship Programme; PDPG6671; 311794 (Elsevier, 2019-12-28)
    Dietary supplementation of pig diets with exogenous enzymes has been suggested as a strategy to increase nutrient digestibility and improve feed efficiency in grow-finisher pigs. However, inconsistent results are found in the literature. Ingredient composition of the diets is one of the most important sources of variation that may affect enzyme efficacy and consistency of results. A systematic review and a meta-analysis was therefore conducted to determine which exogenous enzymes with which diet type most consistently improve pig growth, nutrient digestibility and feed efficiency. Enzyme type and dietary cereal source were the main explanatory variables included in the models. The mean difference effects of enzyme supplementation on average daily gain (ADG), average daily feed intake (ADFI), gain to feed (G:F), apparent ileal digestibility (AiD) and apparent total tract digestibility (ATTD) of dry matter (DM), crude protein (CP), and gross energy (GE) were calculated for each study and these were used as the effect size estimates in the meta-analysis. A dataset with 139 comparisons from 67 peer-reviewed publications was used in the meta-analysis. In response to enzyme supplementation, G:F was improved in 38 of the 120 comparisons reporting pig growth data, remained un-changed in 78 and deteriorated in 4. Overall, DM and GE AiD, and ATTD were improved by xylanase, xylanase + β-glucanase, mannanase and protease dietary supplementation (P < 0.05). Crude protein AiD was only improved by protease dietary supplementation (P < 0.001). Dietary supplementation with xylanase alone improved ADG of maize- (P < 0.05) and co-product- (P < 0.05) based diets but had no effect on the G:F of grow-finisher pigs. Dietary supplementation with xylanase + β-glucanase had no effect on ADG, ADFI and G:F. Protease supplementation tended to improve the ADG of grow-finisher pigs fed co-product-based diets (P = 0.08) but had no effect on G:F. Dietary supplementation with multi-enzyme complexes improved the ADG (P < 0.05) and G:F (P < 0.01) of maize-, wheat-, barley- and co-product-based diets. In conclusion, dietary supplementation with all enzyme types improved nutrient digestibility depending on ingredient content, while mannanase and multi-enzyme complex supplementation most consistently improved growth and feed efficiency.
  • A consumer study of the effect of castration and slaughter age of lambs on the sensory quality of meat

    Gravador, Rufielyn S.; Pace, Elaine; Mooney, Bernard R.; Jaeger, Sara R.; Gkarane, Vasiliki; Fahey, Alan G.; Brunton, Nigel P.; Claffey, Noel A.; Allen, Paul; Diskin, Michael G.; et al. (Elsevier, 2018-09-20)
    Meat from ram lambs is often considered inferior to meat from castrated lambs, especially in older or heavier animals. This study aimed to determine if differences exist in the sensory quality and acceptability of meat from rams and castrates, slaughtered at mean ages of 196 or 385 days. Rams had higher average daily gain, feed conversion efficiency, total weight gain and lower carcass fatness than castrates. A triangle test (n = 81 consumers) showed a difference (P < 0.05) in the sensory quality of meat from rams vs castrates. A 9-point hedonic test involving 100 consumers showed that, although meat from both rams and castrates was ‘liked’, meat from castrates scored higher (P < 0.05) in Overall Liking, Flavour Liking and Tenderness Liking. Meat from castrates was also rated lower (P < 0.05) in Unpleasant Taste/Off-Flavour Intensity. Flavour Intensity and Unpleasant Taste/Off-Flavour Intensity increased (P < 0.05) with age at slaughter. This consumer study revealed that while meat from castrates was higher in Overall Liking, Flavour Liking and Tenderness Liking and lower in Unpleasant Taste/Off-Flavour Intensity than meat from rams, both meats were ‘liked’ by consumers.
  • A case study of the carbon footprint of milk from high-performing confinement and grass-based dairy farms

    O’Brien, Donal; Judith Louise, Capper; Garnsworthy, Phil; Grainger, Chris; Shalloo, Laurence; European Union; FP7-244983 (Elsevier, 2014-01-17)
    Life-cycle assessment (LCA) is the preferred methodology to assess carbon footprint per unit of milk. The objective of this case study was to apply an LCA method to compare carbon footprints of high-performance confinement and grass-based dairy farms. Physical performance data from research herds were used to quantify carbon footprints of a high-performance Irish grass-based dairy system and a top-performing United Kingdom (UK) confinement dairy system. For the US confinement dairy system, data from the top 5% of herds of a national database were used. Life-cycle assessment was applied using the same dairy farm greenhouse gas (GHG) model for all dairy systems. The model estimated all on- and off-farm GHG sources associated with dairy production until milk is sold from the farm in kilograms of carbon dioxide equivalents (CO2-eq) and allocated emissions between milk and meat. The carbon footprint of milk was calculated by expressing GHG emissions attributed to milk per tonne of energy-corrected milk (ECM). The comparison showed that when GHG emissions were only attributed to milk, the carbon footprint of milk from the Irish grass-based system (837 kg of CO2-eq/t of ECM) was 5% lower than the UK confinement system (884 kg of CO2-eq/t of ECM) and 7% lower than the US confinement system (898 kg of CO2-eq/t of ECM). However, without grassland carbon sequestration, the grass-based and confinement dairy systems had similar carbon footprints per tonne of ECM. Emission algorithms and allocation of GHG emissions between milk and meat also affected the relative difference and order of dairy system carbon footprints. For instance, depending on the method chosen to allocate emissions between milk and meat, the relative difference between the carbon footprints of grass-based and confinement dairy systems varied by 3 to 22%. This indicates that further harmonization of several aspects of the LCA methodology is required to compare carbon footprints of contrasting dairy systems. In comparison to recent reports that assess the carbon footprint of milk from average Irish, UK, and US dairy systems, this case study indicates that top-performing herds of the respective nations have carbon footprints 27 to 32% lower than average dairy systems. Although differences between studies are partly explained by methodological inconsistency, the comparison suggests that potential exists to reduce the carbon footprint of milk in each of the nations by implementing practices that improve productivity.
  • Carcass characteristics of cattle differing in Jersey proportion

    Berry, Donagh P.; Judge, Michelle; Evans, R. D.; Buckley, Frank; Cromie, A. R.; Science Foundation Ireland; Department of Agriculture, Food and Marine; Meat Technology Ireland; Enterprise Ireland; 16/RC/3835; et al. (Elsevier, 2018-09-27)
    Comparison of alternative dairy (cross-)breeding programs requires full appraisals of all revenues and costs, including beef merit. Few studies exist on carcass characteristics of crossbred dairy progeny originating from dairy herds as well as their dams. The objective of the present study was to quantify, using a national database, the carcass characteristics of young animals and cows differing in their fraction of Jersey. The data set consisted of 117,593 young animals and 42,799 cows. The associations between a combination of sire and dam breed proportion (just animal breed proportion when the dependent variable was on cows) with age at slaughter (just for young animals), carcass weight, conformation, fat score, price per kilogram, and total carcass value were estimated using mixed models that accounted for covariances among herdmates of the same sex slaughtered in close proximity in time; we also accounted for age at slaughter in young animals (which was substituted with carcass weight and carcass fat score when the dependent variable was age at slaughter), animal sex, parity of the cow or dam (where relevant), and temporal effects represented by a year-by-month 2-way interaction. For young animals, the heaviest of the dairy carcasses were from the mating of a Holstein-Friesian dam and a Holstein-Friesian sire (323.34 kg), whereas the lightest carcasses were from the mating of a purebred Jersey dam to a purebred Jersey sire which were 46.31 kg lighter (standard error of the difference = 1.21 kg). The young animal carcass weight of an F1 Holstein-Friesian × Jersey cross was 20.4 to 27.0 kg less than that of a purebred Holstein-Friesian animal. The carcass conformation of a Holstein-Friesian young animal was 26% superior to that of a purebred Jersey, translating to a difference of 0.78 conformation units on a scale of 1 to 15. Purebred Holstein-Friesians produced carcasses with less fat than their purebred Jersey counterparts. The difference in carcass price per kilogram among the alternative sire-dam breed combinations investigated was minimal, although large differences existed among the different breed types for overall carcass value; the carcass value of a Holstein-Friesian animal was 20% greater than that of a Jersey animal. Purebred Jersey animals required, on average, 21 d longer to reach a given carcass weight and fat score relative to a purebred Holstein-Friesian. The difference in age at slaughter between a purebred Holstein-Friesian animal and the mating between a Holstein-Friesian sire with a Jersey dam, and vice versa, was between 7.0 and 8.9 d. A 75.8-kg difference in carcass weight existed between the carcass of a purebred Jersey cow and that of a Holstein-Friesian cow; a 50% Holstein–Friesian-50% Jersey cow had a carcass 42.0 kg lighter than that of a purebred Holstein-Friesian cow. Carcass conformation was superior in purebred Holstein-Friesian compared with purebred Jersey cows. Results from this study represent useful input parameters to populate simulation models of alternative breeding programs on dairy farms, and to help beef farmers evaluate the cost-benefit of rearing, for slaughter, animals differing in Jersey fraction.
  • The effect of exogenous glucose infusion on early embryonic development in lactating dairy cows

    Leane, S.; Herlihy, Mary M.; Curran, F.; Kenneally, J.; Forde, Niamh; Simintiras, Constantine A.; Sturmey, Roger G.; Lucy, Matt C.; Lonergan, P.; Butler, Stephen T.; et al. (American Dairy Science Association, 2018-09-27)
    The objective of this study was to examine the effect of intravenous infusion of glucose on early embryonic development in lactating dairy cows. Nonpregnant, lactating dairy cows (n = 12) were enrolled in the study (276 ± 17 d in milk). On d 7 after a synchronized estrus, cows were randomly assigned to receive an intravenous infusion of either 750 g/d of exogenous glucose (GLUC; 78 mL/h of 40% glucose wt/vol) or saline (CTRL; 78 mL/h of 0.9% saline solution). The infusion period lasted 7 d and cows were confined to metabolism stalls for the duration of the study. Coincident with the commencement of the infusion on d 7 after estrus, 15 in vitro-produced grade 1 blastocysts were transferred into the uterine horn ipsilateral to the corpus luteum. All animals were slaughtered on d 14 to recover conceptuses, uterine fluid, and endometrial tissue. Glucose infusion increased circulating glucose concentrations (4.70 ± 0.12 vs. 4.15 ± 0.12 mmol/L) but did not affect milk production or dry matter intake. Circulating β-hydroxybutyrate concentrations were decreased (0.51 ± 0.01 vs. 0.70 ± 0.01 mmol/L for GLUC vs. CTRL, respectively) but plasma fatty acids, progesterone, and insulin concentrations were unaffected by treatment. Treatment did not affect either uterine lumen fluid glucose concentration or the mRNA abundance of specific glucose transporters in the endometrium. Mean conceptus length, width, and area on d 14 were reduced in the GLUC treatment compared with the CTRL treatment. A greater proportion of embryos in the CTRL group had elongated to all length cut-off measurements between 11 and 20 mm (measured in 1-mm increments) compared with the GLUC treatment. In conclusion, infusion of glucose into lactating dairy cows from d 7 to d 14 post-estrus during the critical period of conceptus elongation had an adverse impact on early embryonic development.
  • Plane of nutrition affects the phylogenetic diversity and relative abundance of transcriptionally active methanogens in the bovine rumen

    McGovern, Emily; McCabe, Matthew; Cormican, Paul; Popova, Milka; Keogh, Kate; Kelly, Alan K; Kenny, David A.; Waters, Sinead M. (Springer Nature, 2017-10-12)
    Methane generated during enteric fermentation in ruminant livestock species is a major contributor to global anthropogenic greenhouse gas emissions. A period of moderate feed restriction followed by ad libitum access to feed is widely applied in cattle management to exploit the animal’s compensatory growth potential and reduce feed costs. In the present study, we utilised microbial RNA from rumen digesta samples to assess the phylogenetic diversity of transcriptionally active methanogens from feed-restricted and non-restricted animals. To determine the contribution of different rumen methanogens to methanogenesis during dietary restriction of cattle, we conducted high-throughput mcrA cDNA amplicon sequencing on an Illumina MiSeq and analysed both the abundance and phylogenetic origin of different mcrA cDNA sequences. When compared to their unrestricted contemporaries, in feed-restricted animals, the methanogenic activity, based on mcrA transcript abundance, of Methanobrevibacter gottschalkii clade increased while the methanogenic activity of the Methanobrevibacter ruminantium clade and members of the Methanomassiliicoccaceae family decreased. This study shows that the quantity of feed consumed can evoke large effects on the composition of methanogenically active species in the rumen of cattle. These data potentially have major implications for targeted CH4 mitigation approaches such as anti-methanogen vaccines and/or tailored dietary management.
  • Effects of castration and slaughter age on the fatty acid composition of ovine muscle and adipose tissue from two breeds

    Gravador, Rufielyn S.; Moloney, Aidan P; Brunton, Nigel; Gkarane, Vasiliki; Allen, Paul; Fahey, Alan G; Claffey, Noel A.; Diskin, Michael G.; Farmer, Linda J.; Monahan, Frank J; et al. (Elsevier, 2018-10-04)
    Fatty acids (g/100 g total fatty acids) in M. longissimus thoracis et lumborum (LTL) and total branched chain fatty acids (μg/g fat) in subcutaneous adipose tissue (SAT) of rams and castrates from Scottish Blackface (SB) or Texel × Scottish Blackface (T × SB) lambs, slaughtered at mean ages of 196, 242, 293, 344 or 385 days were determined. Lambs were fed pasture prior to a 36-day finishing period on a barley/maize-based concentrate ration. The intramuscular fat content (IMF; %) was higher (P < 0.001) in castrates than in rams and in SB compared to T × SB lambs (P < 0.001). The proportions of c9-C18:1 and total monounsaturated fatty acids (MUFA) were higher (P < 0.001) in LTL of castrates than rams. The proportions of C18:2n-6 and total n-6 polyunsaturated fatty acids (PUFA) were lower (P = 0.001) in LTL of castrates compared to rams related to differences in IMF content. The proportions of C14:0, C16:0, c9-C18:1 and total MUFA were higher (P < 0.05), while the proportions of C18:2n-6, C20:4n-6, C20:5n-3, total PUFA, n-6 and n-3 PUFA were lower (P < 0.05), in SB than in T × SB lambs, which was related to differences in IMF content. There was a higher (P < 0.001) proportion of conjugated linoleic acid (CLA) c9,t11-C18:2 in LTL from SB compared to T × SB. The effects of slaughter age on the proportions of fatty acids in LTL did not show a clear trend. The concentration of 4-methylnonanoic acid was higher (P = 0.002) in SAT of rams than castrates, particularly in older lambs. Despite the differences in the muscle fatty acid composition due to gender, slaughter age or breed of lambs, the ratio of n-6/n-3 PUFA (≤3.11) was within the dietary recommendation of <4.0 for human health.
  • Associations between colostrum management, passive immunity, calf-related hygiene practices, and rates of mortality in preweaning dairy calves

    Barry, John; Bokkers, Eddie A.M.; Berry, Donagh P.; de Boer, Imke J.M.; McClure, J. Trenton; Kennedy, Emer; Teagasc Walsh Fellowship Programme (Elsevier, 2019-09-11)
    Calves are particularly vulnerable to health issues before weaning and experience high rates of mortality. Poor colostrum quality or substandard colostrum management, combined with poor hygiene, can increase disease susceptibility, contributing to elevated mortality rates. This study aimed to assess colostrum and calf management together with subsequent mortality rates in preweaning calves. Forty-seven Irish spring-calving, pasture-based dairy herds were enrolled in the study. To investigate whether colostrum and hygiene practices change as the calving season progresses, each farm was visited in both the first and last 6 wk of the calving season. The concentration of IgG in 250 colostrum samples and 580 calf serum samples was determined by radial immunodiffusion assay. Mean colostrum IgG concentration was 85 mg/mL, and mean calf serum IgG concentration was 30.9 and 27.1 mg/mL, respectively, in the first and last 6 wk of the calving season. Smaller herd size and younger age at sampling were associated with higher calf serum IgG concentration. Dairy breed calves were associated with higher serum IgG concentrations compared with beef breed calves; no association was detected based on sex. For feeding equipment hygiene, we assessed the presence of protein residues and found that hygiene levels tended to worsen from the first to the final 6 wk of the calving season. We found no association between feeding equipment hygiene and herd size or 28-d calf mortality rate. Colostrum and calf management practices were not associated with either calf serum IgG concentration or 28-d calf mortality rate. We found that IgG concentration in colostrum produced in Irish dairy herds was generally good, although large variation existed, emphasizing the need for assessment of colostrum before feeding. Results also suggested that hygiene practices associated with calf rearing can be improved, particularly in the latter half of the calving season.
  • Anti-Müllerian hormone in grazing dairy cows: Identification of factors affecting plasma concentration, relationship with phenotypic fertility, and genome-wide associations

    Gobikrushanth, M.; Purfield, Deirdre C; Canadas, E. R.; Herlihy, Mary M.; Kenneally, J.; Murray, Margaret; Kearney, Francis; Colazo, M. G.; Ambrose, D. J.; Butler, Stephen T.; et al. (Elsevier, 2019-09-11)
    The objectives of this study were to (1) characterize the distribution and variability of plasma anti-Müllerian hormone (AMH) concentration; (2) evaluate factors associated with phenotypic variation in plasma AMH; (3) examine the associations between categories of plasma AMH and reproductive outcomes [pregnancy to first artificial insemination (P/AI), and pregnancy rates within 21, 42, and 84 d after the mating start date (MSD)]; (4) estimate pedigree and genomic heritability for plasma AMH; and (5) identify and validate SNP associated with phenotypic variation in plasma AMH. Plasma AMH concentration (pg/mL) was determined from a blood sample collected (mean ± standard deviation) 10 ± 2 d after first insemination at detected estrus (IDE) in 2,628 first- and second-parity Irish dairy cows. Overall, plasma AMH had a positively skewed distribution with mean (± standard deviation), median, minimum, and maximum concentrations of 326 ± 231, 268, 15, and 2,863 pg/mL, respectively. Plasma AMH was greatest for Jersey, followed by Holstein × Jersey, Holstein × Norwegian Red, and Holstein cows (410, 332, 284, and 257 pg/mL, respectively). Second-parity cows had greater plasma AMH than first-parity cows (333 vs. 301 pg/mL, respectively). Samples collected at 7 and 8 d after first IDE had lesser plasma AMH than those collected on d 9, 10, 11, 12, and 13 after first IDE (291 and 297 vs. 317, 319, 331, 337, and 320 pg/mL). Plasma AMH was not associated with either body condition score at first IDE or the interval from calving to MSD. Cows were categorized into low (≤150 pg/mL; n = 526; lowest 20%), intermediate (>150 to ≤461 pg/mL; n = 1,576; intermediate 60%), and high AMH (>461 pg/mL; n = 526; highest 20%) groups based on plasma AMH, and associations with reproductive outcomes were tested. Cows with high and intermediate plasma AMH had 1.42- and 1.51-times-greater odds of becoming pregnant within 84 d after the MSD than those with low plasma AMH (90.3 and 90.8 vs. 86.8%, respectively); however, P/AI and pregnancy rate within 21 and 42 d after the MSD did not differ among AMH categories. Plasma AMH was moderately heritable (pedigree heritability of 0.40 ± 0.06 and genomic heritability of 0.45 ± 0.05), and 68 SNP across Bos taurus autosomes 7 and 11 were associated with phenotypic variation in plasma AMH. Out of 68 SNP, 42 were located in a single quantitative trait locus on Bos taurus autosome 11 that harbored 6 previously identified candidate genes (NR5A1, HSPA5, CRB2, DENND1A, NDUFA8, and PTGS) linked to fertility-related phenotypes in dairy cows.
  • Evaluation of the n-alkane technique for estimating herbage dry matter intake of dairy cows offered herbage harvested at two different stages of growth in summer and autumn

    Wright, Marliene; Lewis, Eva; Garry, B.; Galvin, Norann; Dunshea, Frank; Hannah, M.C.; Auldist, Martin J.; Wales, W.J.; Dillon, Pat; Kennedy, Emer; et al. (Elsevier, 2018-11-10)
    The n-alkane technique for estimating herbage dry matter intake (DMI) of dairy cows was investigated in this experiment. Eight Holstein-Friesian dairy cows were offered perennial ryegrass ad libitum that had been harvested at two different herbage masses and during two different seasons, in order to assess the effect of herbage mass and season on the accuracy of the n-alkane technique. Two pre-harvested herbage mass treatments (low, target 1500 kg DM/ha versus high, target 4000 kg DM/ha, measured above 4 cm), were investigated in a crossover factorial arrangement within each of two seasons (summer versus autumn), in Ireland. Each season consisted of two periods, each 12 days in length. Cows were housed in individual metabolism stalls to allow for accurate determination of measured DMI. Herbage DMI was estimated, with the n-alkane technique, by dosing cows twice daily with a C32 n-alkane. Pre-harvest herbage mass and season did not affect the n-alkane estimated DMI, although lack of season and herbage mass effects may have been masked by variation that occurred between swards within the same herbage mass and season. However, there were a number of differences between summer and autumn in the fecal recovery rates of a number of n-alkanes suggesting that the effect of season requires further investigation prior to the application of recovery rates from literature values when investigating diet selection and botanical composition. Overall, the n-alkane technique provided good estimates of DMI; the discrepancy had a standard deviation due to sward of 1.2 and 1.0 kg DM/cow per day, and hence potential bias of up to twice this, and a measurement error standard deviation of 1.3 and 1.0 kg DM/cow per day, for the C33/C32 and C31/C32 n-alkane pair methods respectively. Two n-alkane pairs were tested, and C33/C32 n-alkane provided the most precise estimates of DMI, compared with the C31/C32 n-alkane pair. This research provides some strong evidence for future use of the n-alkane technique including that the accuracy of the technique has not been influenced by contemporary changes to herbage management, is not affected by seasonal changes, and overall is an accurate and precise technique for estimating DMI.
  • Genetic parameters for animal mortality in pasture-based, seasonal-calving dairy and beef herds

    Ring, Siobhan C.; Evans, R. D.; Doherty, Michael L.; Berry, Donagh P.; Department of Agriculture, Food and the Marine; 14/S/801 (Elsevier, 2018-11-09)
    In the absence of informative health and welfare phenotypes, breeding for reduced animal mortality could improve overall health and welfare, provided genetic variability in animal mortality exists. The objective of the present study was to estimate genetic (and other) variance components for animal mortality in pasture-based, seasonal-calving dairy and beef herds across multiple life stages as well as to quantify the genetic relationship in mortality among life stages. National mortality records were available for all cattle born in the Republic of Ireland. Cattle were grouped into three life stages based on age (0 to 30 days, 31 to 365 days, 366 to 1095 days) whereas females with ≥1 calving event were also grouped into five life stages, based on parity number (1, 2, 3, 4, and 5), considering both the initial 60 days of lactation and a cow's entire lactation period, separately. The mean mortality prevalence ranged from 0.70 to 5.79% in young animals and from 0.53 to 3.86% in cows. Variance components and genetic correlations were estimated using linear mixed models using 21,637 to 100,993 records. Where heritability estimates were different from zero, direct heritability estimates for mortality in young animals (≤1095 days) ranged from 0.006 to 0.040, whereas the genetic standard deviation ranged from 0.015 to 0.034. The contribution of a maternal genetic effect to mortality in young animals was evident up to 30 days of age in dairy herds, but this was only the case in preliminary analysis of stillbirths in beef herds. Based on the estimated genetic standard deviation in the present study, the incidence of mortality in young animals could be reduced through breeding by up to 3.4 percentage units per generation. For cows, direct heritability estimates for mortality, where different from zero, ranged from 0.003 to 0.049. The genetic standard deviation for mortality in cows ranged from 0.005 to 0.016 during the initial 60 days of lactation and ranged from 0.011 to 0.032 during the cow's entire lactation. Genetic correlations among the age groups as well as between the age groups and cow parities had high standard errors. Genetic correlations among the cow parities were moderate to strongly positive (ranging from 0.66 to 0.99) and mostly different from zero. Results from the present study can be used to inform genetic evaluations for mortality in young animals and in cows as well as the potential genetic gain achievable.
  • Transcriptome analyses reveal reduced hepatic lipid synthesis and accumulation in more feed efficient beef cattle

    Mukiibi, Robert; Vinsky, Michael; Fitzsimmons, Carolyn; Stothard, Paul; Waters, Sinéad M.; Li, Changxi; Keogh, Kate; Alberta Livestock and Meat Agency; Alberta Agriculture and Forestry; Teagasc Walsh Fellowship Programme; et al. (Nature Publishing Group, 2018-05-08)
    The genetic mechanisms controlling residual feed intake (RFI) in beef cattle are still largely unknown. Here we performed whole transcriptome analyses to identify differentially expressed (DE) genes and their functional roles in liver tissues between six extreme high and six extreme low RFI steers from three beef breed populations including Angus, Charolais, and Kinsella Composite (KC). On average, the next generation sequencing yielded 34 million single-end reads per sample, of which 87% were uniquely mapped to the bovine reference genome. At false discovery rate (FDR) < 0.05 and fold change (FC) > 2, 72, 41, and 175 DE genes were identified in Angus, Charolais, and KC, respectively. Most of the DE genes were breed-specific, while five genes including TP53INP1, LURAP1L, SCD, LPIN1, and ENSBTAG00000047029 were common across the three breeds, with TP53INP1, LURAP1L, SCD, and LPIN1 being downregulated in low RFI steers of all three breeds. The DE genes are mainly involved in lipid, amino acid and carbohydrate metabolism, energy production, molecular transport, small molecule biochemistry, cellular development, and cell death and survival. Furthermore, our differential gene expression results suggest reduced hepatic lipid synthesis and accumulation processes in more feed efficient beef cattle of all three studied breeds.
  • The CD4+ T cell methylome contributes to a distinct CD4+ T cell transcriptional signature in Mycobacterium bovis-infected cattle

    Doherty, Rachael; Whiston, Ronan; Cormican, Paul; Finlay, Emma K.; Couldrey, Christine; Brady, Colm; O’Farrelly, Cliona; Meade, Kieran G; Teagasc Walsh Fellowship Programme (Nature Publishing Group, 2016-08-10)
    We hypothesised that epigenetic regulation of CD4+ T lymphocytes contributes to a shift toward a dysfunctional T cell phenotype which may impact on their ability to clear mycobacterial infection. Combined RNA-seq transcriptomic profiling and Reduced Representation Bisulfite Sequencing identified 193 significantly differentially expressed genes and 760 differentially methylated regions (DMRs), between CD4+ T cells from M. bovis infected and healthy cattle. 196 DMRs were located within 10 kb of annotated genes, including GATA3 and RORC, both of which encode transcription factors that promote TH2 and TH17 T helper cell subsets respectively. Gene-specific DNA methylation and gene expression levels for the TNFRSF4 and Interferon-γ genes were significantly negatively correlated suggesting a regulatory relationship. Pathway analysis of DMRs identified enrichment of genes involved in the anti-proliferative TGF-β signaling pathway and TGFB1 expression was significantly increased in peripheral blood leukocytes from TB-infected cattle. This first analysis of the bovine CD4+ T cell methylome suggests that DNA methylation directly contributes to a distinct gene expression signature in CD4+ T cells from cattle infected with M. bovis. Specific methylation changes proximal to key inflammatory gene loci may be critical to the emergence of a non-protective CD4+ T cell response during mycobacterial infection in cattle.
  • Identification of possible cow grazing behaviour indicators for restricted grass availability in a pasture-based spring calving dairy system

    Werner, Jessica; Umstatter, Christina; Kennedy, Emer; Grant, Jim; Leso, Lorenzo; Geoghegan, Anne; Shalloo, Laurence; Schick, Matthias; O'Brien, Bernadette; Science Foundation Ireland; et al. (Elsevier, 2018-12-05)
    Precision livestock farming uses biosensors to measure different parameters of individual animals to support farmers in the decision making process. Although sensor development is advanced, there is still little implementation of sensor-based solutions on commercial farms. Especially on pasture-based dairy systems, the grazing management of cows is largely not supported by technology. A key factor in pasture-based milk production is the correct grass allocation to maximize the grass utilization per cow, while optimizing cow performance. Currently, grass allocation is mostly based on subjective eye measurements or calculations per herd. The aim of this study was to identify possible indicators of insufficient or sufficient grass allocation in the cow grazing behaviour measures. A total number of 30 cows were allocated a restricted pasture allowance of 60% of their intake capacity. Their behavioural characteristics were compared to those of 10 cows (control group) with pasture allowance of 100% of their intake capacity. Grazing behaviour and activity of cows were measured using the RumiWatchSystem for a complete experimental period of 10 weeks. The results demonstrated that the parameter of bite frequency was significantly different between the restricted and the control groups. There were also consistent differences observed between the groups for rumination time per day, rumination chews per bolus and frequency of cows standing or lying.
  • Comparative grazing behaviour of lactating suckler cows of contrasting genetic merit and genotype

    McCabe, S.; McHugh, Noirin; O'Connell, Niamh E.; Prendiville, Robert; Department of Agriculture, Food and the Marine; RSF 13/S4/96 (Elsevier, 2018-12-04)
    The objective of this study was to determine if differences in grazing behaviour exist between lactating suckler cows diverse in genetic merit for the national Irish Replacement index and of two contrasting genotypes. Data from 103 cows: 41 high and 62 low genetic merit, 43 beef and 60 beef x dairy (BDX) cows were available over a single grazing season in 2015. Milk yield, grass dry matter intake (GDMI), cow live weight (BW) and body condition score (BCS) were recorded during the experimental period, with subsequent measures of production efficiency extrapolated. Grazing behaviour data were recorded twice in conjunction with aforementioned measures, using Institute of Grassland and Environmental Research headset behaviour recorders. The effect of genotype and cow genetic merit during mid- and late-lactation on grazing behaviour phenotypes, milk yield, BW, BCS and GDMI were estimated using linear mixed models. Genetic merit had no significant effect on any production parameters investigated, with the exception that low genetic merit had a greater BCS than high genetic merit cows. Beef cows were heavier, had a greater BCS but produced less milk per day than BDX. The BDX cows produced more milk per 100 kg BW and per unit intake and had greater GDMI, intake per bite and rate of GDMI per 100 kg BW than beef cows. High genetic merit cows spent longer grazing and took more bites per day but had a lower rate of GDMI than low genetic merit cows, with the same trend found when expressed per unit of BW. High genetic merit cows spent longer grazing than low genetic merit cows when expressed on a per unit intake basis. Absolute rumination measures were similar across cow genotype and genetic merit. When expressed per unit BW, BDX cows spent longer ruminating per day compared to beef. However, on a per unit intake basis, beef cows ruminated longer and had more mastications than BDX. Intake per bite and rate of intake was positively correlated with GDMI per 100 kg BW. The current study implies that despite large differences in grazing behaviour between cows diverse in genetic merit, few differences were apparent in terms of production efficiency variables extrapolated. Conversely, differences in absolute grazing and ruminating behaviour measurements did not exist between beef cows of contrasting genotype. However, efficiency parameters investigated illustrate that BDX will subsequently convert herbage intake more efficiently to milk production.
  • Comparison of modelling techniques for milk-production forecasting

    Murphy, Michael D.; O’Mahony, Michéal J.; Shalloo, Laurence; French, Padraig; Upton, John (Elsevier for American Dairy Science Association, 2014-04-13)
    The objective of this study was to assess the suitability of 3 different modeling techniques for the prediction of total daily herd milk yield from a herd of 140 lactating pasture-based dairy cows over varying forecast horizons. A nonlinear auto-regressive model with exogenous input, a static artificial neural network, and a multiple linear regression model were developed using 3 yr of historical milk-production data. The models predicted the total daily herd milk yield over a full season using a 305-d forecast horizon and 50-, 30-, and 10-d moving piecewise horizons to test the accuracy of the models over long- and short-term periods. All 3 models predicted the daily production levels for a full lactation of 305 d with a percentage root mean square error (RMSE) of ≤12.03%. However, the nonlinear auto-regressive model with exogenous input was capable of increasing its prediction accuracy as the horizon was shortened from 305 to 50, 30, and 10 d [RMSE (%) = 8.59, 8.1, 6.77, 5.84], whereas the static artificial neural network [RMSE (%) = 12.03, 12.15, 11.74, 10.7] and the multiple linear regression model [RMSE (%) = 10.62, 10.68, 10.62, 10.54] were not able to reduce their forecast error over the same horizons to the same extent. For this particular application the nonlinear auto-regressive model with exogenous input can be presented as a more accurate alternative to conventional regression modeling techniques, especially for short-term milk-yield predictions.
  • A mechanistic model for electricity consumption on dairy farms: Definition, validation, and demonstration

    Upton, John; Murphy, Michael D.; Shalloo, Laurence; Groot Koerkamp, Peter W.G.; De Boer, Imke J.M.; INTERREG IVB North-West Europe (Elsevier, 2014-06-07)
    Our objective was to define and demonstrate a mechanistic model that enables dairy farmers to explore the impact of a technical or managerial innovation on electricity consumption, associated CO2 emissions, and electricity costs. We, therefore, (1) defined a model for electricity consumption on dairy farms (MECD) capable of simulating total electricity consumption along with related CO2 emissions and electricity costs on dairy farms on a monthly basis; (2) validated the MECD using empirical data of 1 yr on commercial spring calving, grass-based dairy farms with 45, 88, and 195 milking cows; and (3) demonstrated the functionality of the model by applying 2 electricity tariffs to the electricity consumption data and examining the effect on total dairy farm electricity costs. The MECD was developed using a mechanistic modeling approach and required the key inputs of milk production, cow number, and details relating to the milk-cooling system, milking machine system, water-heating system, lighting systems, water pump systems, and the winter housing facilities as well as details relating to the management of the farm (e.g., season of calving). Model validation showed an overall relative prediction error (RPE) of less than 10% for total electricity consumption. More than 87% of the mean square prediction error of total electricity consumption was accounted for by random variation. The RPE values of the milk-cooling systems, water-heating systems, and milking machine systems were less than 20%. The RPE values for automatic scraper systems, lighting systems, and water pump systems varied from 18 to 113%, indicating a poor prediction for these metrics. However, automatic scrapers, lighting, and water pumps made up only 14% of total electricity consumption across all farms, reducing the overall impact of these poor predictions. Demonstration of the model showed that total farm electricity costs increased by between 29 and 38% by moving from a day and night tariff to a flat tariff.
  • A national methodology to quantify the diet of grazing dairy cows

    O'Brien, Donal; Moran, Brian; Shalloo, Laurence (Elsevier, 2018-07-04)
    The unique rumen of dairy cows allows them to digest fibrous forages and feedstuffs. Surprisingly, to date few attempts have been made to develop national methods to gain an understanding on the make-up of a dairy cow's diet, despite the importance of milk production. Consumer interest is growing in purchasing milk based on the composition of the cows' diet and the time they spend grazing. The goal of this research was to develop such a methodology using the national farm survey of Ireland as a data source. The analysis was completed for a 3-yr period from 2013 to 2015 on a nationally representative sample of 275 to 318 dairy farms. Trained auditors carried out economic surveys on farms 3 to 4 times per annum. The auditors collected important additional information necessary to estimate the diet of cows including the length of the grazing season, monthly concentrate feeding, type of forage(s) conserved, and milk production. Annual cow intakes were calculated to meet net energy requirements for production, maintenance, activity, pregnancy, growth, and live weight change using survey data and published literature. Our analysis showed that the average annual cow feed intake on a fresh matter basis ranged from 22.7 t in 2013 to 24.8 t in 2015 and from 4.8 to 5 t on a dry matter basis for the same period. Forage, particularly pasture, was the largest component of the Irish cow diet, typically accounting for 96% of the diet on a fresh matter basis and 82% of dry matter intake over the 3 yr. Within the cows' forage diet, grazed pasture was the dominant component and on average contributed 74 to 77% to the average annual cow fresh matter diet over the period. The proportion of pasture in the annual cow diet as fed was also identified as a good indicator of the time cows spend grazing (e.g., coefficient of determination = 0.85). Monthly, forage was typically the main component of the cow diet, but the average contribution of concentrate was substantial for the early spring months of January and February (30 to 35% of dry matter intake). Grazed pasture was the dominant source of forage from March to October and usually contributed 95 to 97% of the diet as fed in the summer period. Overall, the national farm survey from 2013 to 2015 shows that Irish dairy farms are very reliant on forage, particularly pasture, regardless of whether it is reported on a dry matter basis or as fed. There is potential to replicate this methodology in any regions or nations where representative farm surveys are conducted.

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