• Quantification of nutrient supply in forage-based diets for beef cattle

      McGee, Mark; Owens, David; O’Kiely, Padraig; Teagasc Walsh Fellowship Programme (Teagasc, 2009-12-01)
      Introduction Cattle rearing systems in Ireland are predominantly grass-based as 80% of agricultural land is dedicated to grassland (silage, hay and pasture) (CSO, 2007). Feed costs represent the largest single variable cost in beef production in Ireland. Grazed grass is generally the cheapest source of food available for beef (and milk) production provided that the environment and management permit high yields of high quality herbage to be utilised (McGee, 2000). Environmental legislation and the rules of environmental schemes such as the European Union (EU) Rural Environmental Protection Scheme are progressively restricting the application of fertilizer Nitrogen (N), and many grazing systems are becoming more extensive. Over 80% of all farms in Ireland make grass silage (O’Kiely et al., 1998) and it accounts for 87% of total grass conserved (Mayne and O’Kiely, 2005). The deficiencies in nutrient supply to beef cattle from grass silage are usually overcome by supplementing with concentrates (McGee, 2005), which are primarily cereal-based (Drennan et al., 2006). However, diverse types of concentrates containing a variety of feed ingredients, particularly non-cereal by-products are available and frequently fed as supplements to grass silage or as highconcentrate diets. The relatively small amount of information available on feeding these contrasting concentrates to beef cattle is inconsistent. Moreover, there has been an increased use of other ensiled forages such as maize and whole-crop cereals. These forages have high intake potential and can reduce the concentrate feeding level, while maintaining or increasing performance of beef cattle (Keady, 2005). With increasing costs of beef production and increasing constraints of environmental regulations, efficient utilisation of consumed nutrients by cattle is imperative in providing sustainable production and income to farmers. Feed evaluation systems are used to match the dietary nutrient supply with animal requirements for a specific level of production (Dijkstra et al., 2007). These systems are important in order to optimise the efficiency of feed utilisation, to improve animal performance and to reduce nutrient losses to the environment (Dijkstra et al., 2007). Although the reticulo-rumen is central to the profile of nutrients available for absorption, yet quantitative knowledge of the rates of passage and the digestion of nutrients in the rumen is limited compared with that on degradation rates (Dijkstra et al., 2007). There is a lack of information that adequately characterises the supply of nutrients from forages and feedstuffs specific to Ireland, especially for fresh grass-based diets of which, there are very few studies reported in the literature. This shortcoming impedes our ability to capitalise on the merits of evolving feeding systems. This project aimed to: 1. Increase the knowledge and advance the understanding on rumen digestion and nutrient flow from the rumen of the main forages / forage-based diets offered to beef cattle in Ireland. 2. Evaluate strategies for optimal utilization of nutrients consumed by cattle.
    • Quantitative analysis of ruminal methanogenic microbial populations in beef cattle divergent in phenotypic residual feed intake (RFI) offered contrasting diets

      Carberry, Ciara, A; Kenny, David, A; Kelly, Alan, K; Waters, Sinead M.; Department of Agriculture, Food and the Marine; RSF 05 224 (Biomed Central, 2014-08-22)
      Background Methane (CH4) emissions in cattle are an undesirable end product of rumen methanogenic fermentative activity as they are associated not only with negative environmental impacts but also with reduced host feed efficiency. The aim of this study was to quantify total and specific rumen microbial methanogenic populations in beef cattle divergently selected for residual feed intake (RFI) while offered (i) a low energy high forage (HF) diet followed by (ii) a high energy low forage (LF) diet. Ruminal fluid was collected from 14 high (H) and 14 low (L) RFI animals across both dietary periods. Quantitative real time PCR (qRT-PCR) analysis was conducted to quantify the abundance of total and specific rumen methanogenic microbes. Spearman correlation analysis was used to investigate the association between the relative abundance of methanogens and animal performance, rumen fermentation variables and diet digestibility. Results Abundance of methanogens, did not differ between RFI phenotypes. However, relative abundance of total and specific methanogen species was affected (P < 0.05) by diet type, with greater abundance observed while animals were offered the LF compared to the HF diet. Conclusions These findings suggest that differences in abundance of specific rumen methanogen species may not contribute to variation in CH4 emissions between efficient and inefficient animals, however dietary manipulation can influence the abundance of total and specific methanogen species.
    • Ranking of Sire Breeds and Beef Cross Breeding of Dairy and Beef Cows

      Keane, Michael G. (Teagasc, 2011-03-01)
      Summary There is general agreement across countries on the ranking of beef breeds for production and carcass traits. Differences between dairy and early maturing beef breeds in growth and slaughter traits are small, but the latter have lower feed intake and better carcass conformation. Late maturing beef breeds also have lower feed intake and better carcass conformation and in addition, have a higher growth rate, kill-out proportion and carcass muscle proportion. When factors such as age and fatness are accounted for, differences between breeds in meat quality traits are small. Differences amongst breed types in kill-out proportion can be explained by differences in gut contents (consequent on differences in feed intake), differences in the proportions of gastrointestinal tract and metabolic organs, differences in hide proportion, and differences in offal fats. Growth is an allometric, rather than an isometric, process. Some parts, organs and tissues grow relatively more slowly than the animal overall, and so become decreasing proportions over time, while others grow relatively faster and become increasing proportions. With increasing slaughter weight, the proportions of non carcass parts, hind quarter, bone, total muscle and higher value muscle decrease, while the proportions of non carcass and carcass fats, fore quarter and marbling fat all increase. Because of heterosis or hybrid vigour, the productivity of cross-bred cattle is superior to the mean of the parent breeds. While calving difficulty may be slightly higher (probably due to greater birth weight), calf mortality is much reduced in cross-breds. In addition, general robustness and growth rate are increased. There are additive effects of heterosis in the dam and the progeny. When cross-bred cows are mated to a bull of a third breed, >60 % of total heterosis is attributable to the cross-bred cows. The double muscling phenotype in beef cattle is due to the inactivated myostatin gene, but the inactivating mutation is not the same in all breeds and other genes also contribute to muscling. Compared to normal animals, double muscled animals have lower proportions of digestive tract, internal fats and metabolic organs. This explains their superior kill-out proportion. They also have a smaller hind shin that helps accentuate the muscling in the remainder of the 4 limb. There are similar degrees of muscular hypertrophy in both the hind and fore quarters. Muscle to bone ratio is about one third greater in double muscled than in normal carcasses. Piedmontese cattle with none, one or two mutated myostatin alleles were compared with normal Herefords and Limousins. In the absence of any mutated allele, Piedmontese were similar to Herefords, with one mutated allele they were similar to Limousins and with two mutated alleles they were immensely superior to Limousins. In fact, the response to the second mutated allele was about three times that to the first. If progeny approximated to the mean of the parent breeds, crossing a double muscled sire with a dairy or early maturing beef cow would result in cattle of similar characteristics to pure-bred late maturing beef breeds. This does not happen because double muscling is dependent on a homozygous myostatin genotype. The progeny of a common cow breed and normal late maturing, or double muscled, sire breeds have similar production traits.
    • Rearing calves outdoors with and without calf jackets compared with indoor housing on calf health and live-weight performance

      Earley, Bernadette; Murray, Margaret; Farrell, J.A.; Nolan, Marie-Jean; National Development Plan, 2000-2006 (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
      The objective of this study was to compare the effects of rearing calves outdoors, with and without all-weather calf jackets, with calves reared indoors on calf immunity and animal performance. In February 1999, male Holstein calves (mean (s.e.) weight 55 (1.90) kg) were randomly assigned to one of three treatments (n=30 per treatment): 1) outdoors with jacket, (J; mean age 19 (s.e. 2.0) days); 2) outdoors without jacket (NJ; mean age 19 (s.e. 1.8) days), and 3) indoors on straw (I; mean age 19 (s.e. 1.0) days). Calves received an individual allowance of 25 kg of milk replacer dry matter during the first 42 days with ad libitum access to a concentrate ration from day 0 to 63. The jackets were removed from the calves on day 42. Live-weight gain from day 0 to day 63 of the study was not significantly different between treatments (J, 0.79; NJ, 0.80; I, 0.80 kg). Sixty percent of the J calves and 53% of the NJ calves required four or more antibiotic treatments for respiratory disease while corresponding treatments were required for 97% of the I calves. The incidence of diarrhoea was significantly higher in both outdoor treatments compared to the I treatment. There was no significant difference in white blood cell counts or in serum immunoglobulin concentrations between treatments on days 0, 21, 42 and 63 or in in vitro interferon-γ production on day 63. It is concluded that using calf jackets on calves reared outdoors had no beneficial effect on calf performance or immune status. The incidence of respiratory disease was higher and diarrhoea incidence was lower in calves reared indoors compared with calves reared outdoors. There was no significant difference in incidences of diarrhoea and respiratory disease between the two outdoor treatments.
    • Relationship between dairy cow genetic merit and profit on commercial spring calving dairy farms

      Ramsbottom, George; Cromie, A. R.; Horan, Brendan; Berry, Donagh P. (Cambridge University Press, 2011-12)
      Because not all animal factors influencing profitability can be included in total merit breeding indices for profitability, the association between animal total merit index and true profitability, taking cognisance of all factors associated with costs and revenues, is generally not known. One method to estimate such associations is at the herd level, associating herd average genetic merit with herd profitability. The objective of this study was to primarily relate herd average genetic merit for a range of traits, including the Irish total merit index, with indicators of performance, including profitability, using correlation and multiple regression analyses. Physical, genetic and financial performance data from 1131 Irish seasonal calving pasture-based dairy farms were available following edits; data on some herds were available for more than 1 year of the 3-year study period (2007 to 2009). Herd average economic breeding index (EBI) was associated with reduced herd average phenotypic milk yield but with greater milk composition, resulting in higher milk prices. Moderate positive correlations (0.26 to 0.61) existed between genetic merit for an individual trait and average herd performance for that trait (e.g. genetic merit for milk yield and average per cow milk yield). Following adjustment for year, stocking rate, herd size and quantity of purchased feed in the multiple regression analysis, average herd EBI was positively and linearly associated with net margin per cow and per litre as well as gross revenue output per cow and per litre. The change in net margin per cow per unit change in the total merit index was h1.94 (s.e.50.42), which was not different from the expectation of h2. This study, based on a large data set of commercial herds with accurate information on profitability and genetic merit, confirms that, after accounting for confounding factors, the change in herd profitability per unit change in herd genetic merit for the total merit index is within expectations.
    • Relationship between live weight and body condition score in Irish Holstein-Friesian dairy cows

      Berry, Donagh P.; Buckley, Frank; Dillon, Pat (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)
      The objective of this study was to quantify the change in live weight (LWT) per unit change in body condition score (BCS) for Irish Holstein-Friesian dairy cows. Mixed model analyses were performed on 82 948 test-day records of BCS and LWT across 11 075 lactations from 7391 cows, representing 62 commercial and 4 research herds, during the years 1999 and 2000. Factors included in the mixed models were parity, stage of the inter-calving interval and the three-way interaction between herd, year and fortnight of the calendar year at calving. Interactions between the effect of BCS and either parity or stage of the inter-calving interval were included in some models to evaluate the effect of these factors on the relationship between LWT and BCS. A moderate correlation (0.49) existed between BCS and LWT in the complete dataset, but it differed significantly with parity and stage of the inter-calving interval (range 0.36 to 0.59). Analysis of the entire dataset yielded an estimate of 50 kg LWT change per unit change in BCS and this coefficient ranged from 39 kg to 66 kg, depending on parity or the stage of the inter-calving interval. Accurate values of LWT per unit BCS are important input parameters for animal or herd-level biological models designed to evaluate the energy demands of the animal or herd.
    • The relationship between serum anti-Müllerian hormone concentrations and fertility, and genome-wide associations for anti-Müllerian hormone in Holstein cows

      Gobikrushanth, M.; Purfield, Deirdre C; Colazo, M. G.; Butler, Stephen T.; Wang, Z.; Ambrose, D. J.; Growing Forward 2; Alberta Livestock and Meat Agency; Alberta Milk; Teagasc Walsh Fellowship Programme; et al. (Elsevier, 2018-05-07)
      The objectives of this study were to (1) evaluate factors associated with variation in circulating anti-Müllerian hormone (AMH) concentrations, (2) establish an optimum AMH threshold predictive of pregnancy to first artificial insemination (P/AI), (3) examine the relationship between AMH and fertility (P/AI, pregnancy loss between 30 and 60 d after artificial insemination, and pregnancy risk up to 250 d postpartum), and (4) identify quantitative trait loci associated with phenotypic variation of AMH concentrations in dairy cows. Serum AMH concentrations (pg/mL) were determined at 7 ± 2.4 d postpartum in 647 lactating Holstein cows (213 primiparous, 434 multiparous) from 1 research and 6 commercial dairy herds in Alberta, Canada. Of these, 589 cows were genotyped on the 26K Bovine BeadChip (Neogen Inc., Lincoln, NE) and subsequently imputed to the Illumina Bovine High Density BeadChip (Illumina, San Diego, CA) for genome-wide association analysis for variation in serum AMH concentrations. Factors associated with variation in serum AMH concentrations and the relationship between categories of AMH and aforementioned fertility outcomes were evaluated only in a subset of 460 cows that had a complete data set available. The overall mean (±standard error of the mean), median, minimum, and maximum AMH concentrations were 191.1 ± 6.3, 151.7, 13.9, and 1,879.0 pg/mL, respectively. The AMH concentrations were not associated with herd, precalving body condition score, postpartum week, and season of sampling; the lactation number, however, had a quadratic relationship with serum AMH concentrations (116.2, 204.9 204.5, and 157.9 pg/mL for first, second, third, and ≥fourth lactation, respectively). The optimum AMH threshold predictive of P/AI could not be established because the receiver operating characteristic curve analysis model was nonsignificant. Categories of AMH [low (<83.0 pg/mL; n = 92), intermediate (≥83.0 to ≤285.0 pg/mL; n = 276), and high (>285.0 pg/mL; n = 92) based on lowest 20%, intermediate 60%, and highest 20% serum AMH) had no associations with P/AI (34, 43, and 40%), pregnancy loss between 30 and 60 d after artificial insemination (20, 12, and 8%), or pregnancy risk up to 250 d postpartum. One candidate gene associated with AMH production [AMH gene on Bos taurus autosome (BTA) 7] and 4 candidate genes related to embryo development (SCAI and PPP6C genes on BTA11 and FGF18 and EEF2K genes on BTA20 and BTA25, respectively) were in linkage disequilibrium with single nucleotide polymorphisms associated with phenotypic variation in serum AMH in dairy cows.
    • The relationship between serum insulin-like growth factor-1 (IGF-1) concentration and reproductive performance, and genome-wide associations for serum IGF-1 in Holstein cows

      Gobikrushanth, M.; Purfield, Deirdre C; Colazo, M. G.; Wang, Z.; Butler, Stephen T.; Ambrose, D. J.; Growing Forward 2; Alberta Livestock and Meat Agency; Alberta Milk; Teagasc Walsh Fellowship Programme; et al. (Elsevier, 2019-07-19)
      The objectives of this study were to determine (1) factors associated with serum concentration of insulin-like growth factor-1 (IGF-1); (2) the relationship between serum IGF-1 concentration during the first week postpartum and ovarian cyclicity status by 35 d postpartum (DPP); (3) an optimum serum IGF-1 concentration threshold predictive of pregnancy to first artificial insemination (P/AI), including its diagnostic values; (4) the associations among categories of serum IGF-1 concentration and reproductive outcomes (P/AI and pregnancy risk up to 150 and 250 DPP); and (5) single nucleotide polymorphisms (SNP) associated with phenotypic variation in serum IGF-1 concentration in dairy cows. Serum IGF-1 concentration was determined at 7 (±2.4; ±standard error of the mean) DPP in 647 lactating Holstein cows (213 primiparous, 434 multiparous) from 7 herds in Alberta, Canada. The overall mean, median, minimum, and maximum serum IGF-1 concentrations during the first week postpartum were 37.8 (±1.23), 31.0, 20.0, and 225.0 ng/mL, respectively. Herd, age, parity, precalving body condition score, and season of blood sampling were all identified as factors associated with serum IGF-1 concentrations. Although serum IGF-1 concentration during the first week postpartum had no association with ovarian cyclicity status by 35 DPP in primiparous cows, it was greater in cyclic than in acyclic multiparous cows (32.2 vs. 27.4 ng/mL, respectively). The optimum serum IGF-1 thresholds predictive of P/AI were 85.0 ng/mL (sensitivity = 31.9%; specificity = 89.1%) and 31.0 ng/mL (sensitivity = 45.5%; specificity = 66.9%) for primiparous and multiparous cows, respectively. When cows were grouped into either high or low IGF-1 categories (greater or less than or equal to 85.0 ng/mL for primiparous cows and greater or less than or equal to 31.0 ng/mL for multiparous cows, respectively), primiparous cows with high IGF-1 had 4.43 times greater odds of P/AI and a tendency for higher pregnancy risk up to 150 DPP than those with low IGF-1, but not up to 250 DPP. Likewise, multiparous cows with high IGF-1 had 1.61 times greater odds of P/AI than those with low IGF-1. Pregnancy risk up to 150 and 250 DPP, however, did not differ between IGF-1 categories in multiparous cows. Moreover, 37 SNP across 10 Bos taurus autosomes were associated with variation in serum IGF-1 concentration, and 4 previously identified candidate genes related to fertility that were in linkage disequilibrium with some of these SNP were also identified.
    • The relationship between various live animal scores/measurements and carcass classification for conformation and fatness with meat yield and distribution, and ultimate carcass value

      Drennan, Michael J; McGee, Mark; Conroy, S. B.; Keane, Michael G.; Kenny, D.A.; Berry, Donagh P. (Teagasc, 2009-12-01)
      Accordingly, the primary objectives of the following study were to: (1) determine the relationship of live animal muscular and skeletal scores, ultrasonically scanned muscle and fat depth measurements of the m. longissimus dorsi, and carcass conformation and fat scores with kill-out proportion, carcass composition and value. (2) Specifically develop and test the accuracy of prediction equations for carcass meat, fat and bone proportions, derived from carcass conformation and fat scores, and develop prediction equations for total carcass composition from hind-quarter composition.
    • Relative Tissue Growth Patterns and Carcass Composition in Beef Cattle

      Keane, Michael G. (Teagasc, 2011-03-01)
      Summary The main objective of the beef breed evaluation programme carried out at Grange Beef Research Centre was to compare the productive characteristics of different beef breed crosses out of Holstein-Friesian cows. In the course of this work much additional information was acquired, particularly on growth patterns of body organs and tissues, and how these affect kill-out proportion and carcass composition. The data were also used to examine relationships between carcass classification variables and carcass composition. Cattle used for beef production in Ireland can be classified into three main biological types: (i) early maturing, (ii) dairy, and (iii) late maturing. Results from an experiment that compared Friesians (dairy), Hereford × Friesians (early maturing) and Charolais × Friesians (late maturing) are used to represent these biological types. The material is organized under the following headings: (i) non carcass parts and kill-out proportion, (ii) carcass composition, (iii) carcass tissue distribution, (iv) muscle chemical composition, (v) gender, (vi) dairy breeds, and (vii)carcass classification and composition. Kill-out proportion increased by about 10 g/kg from Friesians to Hereford × Friesians to Charolais × Friesians. It also increased by about 10 g/kg per 100 kg increase in slaughter weight. Friesians had higher proportions of gastrointestinal tract plus contents than the two beef crosses and also had higher proportions of metabolic organs. Hereford crosses had a higher proportion of hide and offal fats than Charolais crosses. At any carcass weight, early maturing animals had more fat and less bone and muscle than late maturing animals. As carcass weight increased, the proportions of bone and muscle in the carcass decreased, and the proportion of fat increased, but the rates of these changes differed with biological type. Carcass muscle distribution also differed with biological type. Late maturing cattle had a higher proportion of hind quarter and higher value muscle than Friesians and early maturing animals, while Friesians had higher proportions than early maturing animals. Muscle lipid content (marbling) differed with biological type (early maturing > dairy > late maturing) and with carcass joint (highest for flank and ribs, lowest for m. longissimus). Early maturing steers and heifers had similar carcass fat proportions when the heifers were about 60 kg carcass lighter than the steers. Despite having poorer carcass conformation, heifers had a slightly higher proportion of muscle and a considerably higher proportion of higher value muscle than steers. Carcass classification grade was not a reliable indicator of carcass muscle proportion. Carcass fat class was related to both carcass fat and muscle proportions but accounted for less than half the variance in these. Carcass conformation class was not related to carcass fat proportion, carcass muscle proportion or higher value muscle proportion, but it was negatively related to carcass bone proportion.
    • Requirements of future grass-based ruminant production systems in Ireland

      O'Donovan, Michael; Lewis, Eva; O'Kiely, Padraig (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)
      There is a renewed interest in grazing systems in many temperate and subtropical regions of the world. This results from lower inflation-adjusted prices, the proposed removal of some subsidies and tariffs, and rising labour, machinery and housing costs. The utilization of grass by grazing should provide the basis of sustainable livestock systems as grazed grass is the cheapest source of nutrients for ruminants. This is very important in the Irish context as there are approximately 130 000 farmers involved in primary production in Ireland and the value of the goods produced was €5.8 billion in 2008. For the future, the key objective for grazing systems is to ensure high grass utilization, allowing increased output per hectare for all sectors. The primary emphasis in grass breeding needs to be focused on (i) seasonal growth pattern as well as overall annual growth, (ii) nutritive value, including digestibility, particularly in the mid-season period, (iii) ensuring a sward canopy structure that is suitable for grazing, and (iv) development of persistent cultivars that perform under farm conditions. Evaluation programmes should also consider including an estimate of production potential at the field as well as at plot level, and evaluation under grazing management systems as well as under mixed grazing/silage management systems. It is difficult to accurately quantify the breeding achievements for grass mainly because its value, whether grazed or conserved, must be indirectly realised through the output of animal product. Grass evaluation and breeding need to better accommodate the requirements of the grazing ruminant. This will necessitate the application of new approaches and knowledge, which will ultimately enable further increases in animal output per hectare to be achieved.
    • Residual feed intake phenotype and gender affect the expression of key genes of the lipogenesis pathway in subcutaneous adipose tissue of beef cattle

      McKenna, Clare; Porter, Richard; Keogh, Kate; Waters, Sinead M.; McGee, Mark; Kenny, David; Teagasc Walsh Fellowship Programme (Biomed Central, 2018-09-20)
      Background Feed accounts for up to 75% of costs in beef production systems, thus any improvement in feed efficiency (FE) will benefit the profitability of this enterprise. Residual feed intake (RFI) is a measure of FE that is independent of level of production. Adipose tissue (AT) is a major endocrine organ and the primary metabolic energy reservoir. It modulates a variety of processes related to FE such as lipid metabolism and glucose homeostasis and thus measures of inter-animal variation in adiposity are frequently included in the calculation of the RFI index. The aim of this study was to determine the effect of phenotypic RFI status and gender on the expression of key candidate genes related to processes involved in energy metabolism within AT. Dry matter intake (DMI) and average daily gain (ADG) were measured over a period of 70 d for 52 purebred Simmental heifers (n = 24) and bulls (n = 28) with an initial BW±SD of 372±39.6 kg and 387±50.6 kg, respectively. Residual feed intake was calculated and animals were ranked within gender by RFI into high (inefficient; n = 9 heifers and n = 8 bulls) and low (efficient; n = 9 heifers and n = 8 bulls) groups. Results Average daily gain ±SD and daily DMI ±SD for heifers and bulls were 1.2±0.4 kg and 9.1±0.5 kg, and 1.8±0.3 kg and 9.5±1 kg respectively. High RFI heifers and bulls consumed 10% and 15% more (P < 0.05) than their low RFI counterparts, respectively. Heifers had a higher expression of all genes measured than bulls (P < 0.05). A gender × RFI interaction was detected for HMGCS2(P < 0.05) in which high RFI bulls tended to have lower expression of HMGCS2 than low RFI bulls (P < 0.1), whereas high RFI heifers had higher expression than low RFI heifers (P < 0.05) and high RFI bulls (P < 0.05). SLC2A4 expression was consistently higher in subcutaneous AT of low RFI animals across gender. Conclusion The findings of this study indicate that low RFI cattle exhibit upregulation of the molecular mechanisms governing glucose metabolism in adipose tissue, in particular, glucose clearance. The decreased expression of SLC2A4 in the inefficient cattle may result in less efficient glucose metabolism in these animals. We conclude that SLC2A4 may be a potential biomarker for RFI in cattle.
    • Response to Teladorsagia circumcincta infection in Scottish Blackface lambs with divergent phenotypes for nematode resistance

      McRae, Kathryn M.; Good, Barbara; Hanrahan, James P; Glynn, Assumpta; O'Connell, Mary J.; Keane, Orla M; Teagasc Walsh Fellowship Programme; Allan and Grace Kay Overseas Scholarship (Elsevier, 2014-10-24)
      The objective of this study was to identify Scottish Blackface lambs that were at the extremes of the spectrum of resistance to gastrointestinal nematodes and characterise their response to an experimental nematode challenge. Lambs (n = 90) were monitored for faecal egg count (FEC) (2 samples from each of 2 independent natural infections). The most resistant (n = 10) and susceptible (n = 10) individuals were selected and challenged with 30,000 Teladorsagia circumcincta larvae (L3) at 9 months of age. Response to infection was monitored by measuring FEC, plasma pepsinogen, serum antibodies against nematode larval antigens and haematology profile, until necropsy at 71 days post infection. Worm burden, worm fecundity and the level of anti-nematode antibodies in abomasal mucosa were determined at necropsy. FEC was consistently higher in susceptible animals (P < 0.05), validating the selection method. Worm fecundity was significantly reduced in resistant animals (P = 0.03). There was also a significant correlation (r = 0.88; P < 0.001) between the number of adult worms and FEC at slaughter. There was no effect of phenotype (resistance/susceptibility) on plasma pepsinogen or on haematology profile. Phenotype had a significant effect on the level of anti-nematode IgA antibodies in serum (P < 0.01), reflecting a higher peak in resistant animals at day 7 post infection. It is concluded that significant variation in the response to gastrointestinal nematode challenge exists within the Scottish Blackface population with resistant animals displaying significantly lower FEC, lower worm fecundity and higher concentration of anti-nematode IgA antibodies in serum.
    • Responses of North American and New Zealand strains of Holstein–Friesian dairy cattle to homeostatic challenges during early and mid-lactation

      Patton, Joe; Murphy, J.J.; O'Mara, Frank P.; Butler, Stephen T.; National Development Plan Ireland (Cambridge University Press, 2009-02)
      This study investigated the physiological basis of differences in nutrient partitioning between the North American (NA) and New Zealand (NZ) strains of Holstein Friesian cattle by determining the responses to homeostatic challenges at two stages of lactation. Glucose tolerance tests, epinephrine challenges, and insulin challenges were carried out on consecutive days commencing on day 32 ± 0.48 (mean ± s.e.m) of lactation (T1) and again commencing on day 137 ± 2.44 of lactation (T2). The insulin and non-esterified fatty acid (NEFA) responses to glucose infusion did not differ between the strains. The NZ strain had a greater clearance rate (CR) of glucose (2.04 vs. 1.66 % / min) and tended to have a shorter (34.4 vs. 41.1 min) glucose half-life (t½) at T2 when infused with glucose. The NA cows had a greater glucose response to epinephrine infusion across T1 and T2, and tended to have a greater insulin response to epinephrine infusion. Plasma NEFA concentration declined to similar nadir concentrations for both strains at T1 in response to insulin, though from a higher basal concentration in NA cows, resulting in a greater (-2.29 vs. -1.38) NEFA area under the response curve (AUC) for NA cows. Glucose response to insulin varied with time, tending to be greater for NA at T1, but tending to be lower for NA at T2. The results indicated that NA cows had a greater glycogenolytic response to epinephrine, but both strains had similar lipolytic responses. The results also imply that higher basal circulating NEFA concentrations in the NA strain in early lactation were not due to diminished adipose tissue responsiveness to insulin. There were indications that glucose clearance rate was greater in NZ cows in mid-lactation, and may form the basis of increased body tissue accretion during mid- to late-lactation in this strain.
    • A review of factors influencing litter size in Irish sows

      Lawlor, Peadar G; Lynch, P Brendan (Biomed Central, 2007-06-01)
      Many factors influence litter size. These include genetics, gilt management, lactation length, parity distribution, disease, stress and boar fertility. In the past 20 years, litter size in Irish sows has increased by only one pig. Born alive figures now average at 11.2 pigs per litter. In this regard, Ireland is falling behind our European competitors who have made significant advances over this time. Denmark, for example, has an average figure of 12.7 pigs born alive per litter and France an average of 12.5. The single area that could be improved immediately is sow feeding. It is important that sows are fed correctly throughout pregnancy. If over-fed during pregnancy, sows will have depressed appetite during lactation. If underfed in pregnancy, sows will be too thin at farrowing. The correct way to feed a pregnant sow is to match her feed allocation to her requirement for maintenance, body growth and growth of her developing foetuses. During lactation, sows should be given as much feed as they can eat to prevent excessive loss of body condition. Liquid-feed curves should be such that lactating sows are provided with a minimum mean daily feed supply of 6.2 kg. A small proportion of sows will eat more and this could be given as supplementary dry feed. Where dry feeding is practised in the farrowing house, it is difficult to hand-feed sows to match their appetite. Ideally ad libitum wet/dry feeders should be used. From weaning to service, sows should once again be fed ad libitum. If liquid feeding, this means giving at least 60 MJ DE (digestible energy) per day during this period. If dry feeding, at least 4 kg of lactation diet should be fed daily. The effort spent perfecting sow feeding management on units should yield high dividends in the form of increased pigs born alive per litter.
    • A review of nitrous oxide mitigation by farm nitrogen management in temperate grassland-based agriculture

      Li, Dejun; Watson, Catherine J.; Yan, Ming Jia; Lalor, Stanley T. J.; Rafique, Rashid; Hyde, Bernard; Lanigan, Gary; Richards, Karl G.; Holden, Nicholas M.; Humphreys, James; et al. (Elsevier, 20/07/2013)
      Nitrous oxide (N2O) emission from grassland-based agriculture is an important source of atmospheric N2O. It is hence crucial to explore various solutions including farm nitrogen (N) management to mitigate N2O emissions without sacrificing farm profitability and food supply. This paper reviews major N management practices to lower N2O emission from grassland-based agriculture. Restricted grazing by reducing grazing time is an effective way to decrease N2O emissions from excreta patches. Balancing the protein-to-energy ratios in the diets of ruminants can also decrease N2O emissions from excreta patches. Among the managements of synthetic fertilizer N application, only adjusting fertilizer N rate and slow-released fertilizers are proven to be effective in lowering N2O emissions. Use of bedding materials may increase N2O emissions from animal houses. Manure storage as slurry, manipulating slurry pH to values lower than 6 and storage as solid manure under anaerobic conditions help to reduce N2O emissions during manure storage stage. For manure land application, N2O emissions can be mitigated by reducing manure N inputs to levels that satisfy grass needs. Use of nitrification inhibitors can substantially lower N2O emissions associated with applications of fertilizers and manures and from urine patches. N2O emissions from legume based grasslands are generally lower than fertilizer-based systems. In conclusion, effective measures should be taken at each step during N flow or combined options should be used in order to mitigate N2O emission at the farm level.
    • Review of potential sources and control of thermoduric bacteria in bulk-tank milk

      Gleeson, David E; O'Connell, Aine; Jordan, Kieran; Irish Dairy Levy Research Trust (Teagasc (Agriculture and Food Development Authority), Ireland, 2013)
      Bacteria that contaminate milk include thermoduric bacteria that can survive pasteurisation and subsequently grow in the pasteurised milk or contaminate product. Elimination of thermodurics at milking is not feasible. Therefore, knowledge of their source and strategies for their reduction are important. The major sources of thermodurics in milk are contamination of the teat skin from soil and bedding, and subsequent contamination from deposits that can build up on milking equipment surfaces. Hygiene at milking can reduce the number of bacteria contaminating milk. Teat preparation at milking and a recommended plant cleaning procedure are critical to the prevention of the contamination of milk with thermoduric bacteria.
    • Review of studies on flukicide residues in cows’ milk and their transfer to dairy products

      Power, C.; Sayers, Riona; O'Brien, Bernadette; Furey, A.; Danaher, Martin; Kieran, Jordan; Teagasc Walsh Fellowship Programme (Teagasc (Agriculture and Food Development Authority), Ireland, 2013)
      Flukicides are widely used to treat infestations of liver fluke in dairy cattle. This could result in flukicide residues in milk if animals are improperly treated or if withdrawal periods are not properly observed. The purpose of this review is to summarise the results of studies on depletion of flukicides from milk and the transfer of flukicide residues to dairy products, if present in the milk. As the depletion of flukicide residues from milk of animals treated during lactation was relatively slow, the studies support the view that the dry period (when milk is not being used for human consumption) is the most suitable time for flukicide treatment. Migration of residues to product occurred at different rates, depending on the drug in question. Generally, concentration of flukicides occurred in cheese, butter and skim milk powder. Pasteurisation or heat treatment during spray drying had no impact in reducing residues.
    • Risk factors associated with detailed reproductive phenotypes in dairy and beef cows

      Carthy, T. R.; Berry, Donagh P.; Fitzgerald, A.; McParland, Sinead; Williams, E. J.; Butler, Stephen T.; Cromie, A. R.; Ryan, D.; Department of Agriculture, Food and the Marine; European Union; et al. (Cambridge University PRess, 2014-04-17)
      The objective of this study was to identify detailed fertility traits in dairy and beef cattle from transrectal ultrasonography records and quantify the associated risk factors. Data were available on 148 947 ultrasound observations of the reproductive tract from 75 949 cows in 843 Irish dairy and beef herds between March 2008 and October 2012. Traits generated included (1) cycling at time of examination, (2) cystic structures, (3) early ovulation, (4) embryo death and (5) uterine score; the latter was measured on a scale of 1 (good) to 4 (poor) characterising the tone of the uterine wall and fluid present in the uterus. After editing, 72 773 records from 44 415 dairy and beef cows in 643 herds remained. Factors associated with the logit of the probability of a positive outcome for each of the binary fertility traits were determined using generalised estimating equations; linear mixed model analysis was used for the analysis of uterine score. The prevalence of cycling, cystic structures, early ovulation and embryo death was 84.75%, 3.87%, 7.47% and 3.84%, respectively. The occurrence of the uterine heath score of 1, 2, 3 and 4 was 70.63%, 19.75%, 8.36% and 1.26%, respectively. Cows in beef herds had a 0.51 odds (95% CI = 0.41 to 0.63, P<0.001) of cycling at the time of examination compared with cows in dairy herds; stage of lactation at the time of examination was the same in both herd types. Furthermore, cows in dairy herds had an inferior uterine score (indicating poorer tone and a greater quantity of uterine fluid present) compared with cows in beef herds. The likelihood of cycling at the time of examination increased with parity and stage of lactation, but was reduced in cows that had experienced dystocia in the previous calving. The presence of cystic structures on the ovaries increased with parity and stage of lactation. The likelihood of embryo/foetal death increased with parity and stage of lactation. Dystocia was not associated with the presence of cystic structures or embryo death. Uterine score improved with parity and stage of lactation, while cows that experienced dystocia in the previous calving had an inferior uterine score. Heterosis was the only factor associated with increased likelihood of early ovulation. The fertility traits identified, and the associated risk factors, provide useful information on the reproductive status of dairy and beef cows.
    • Risk factors associated with lambing traits

      McHugh, Noirin; Berry, Donagh P.; Pabiou, T.; Department of Agriculture, Food and the Marine; RSF 11/S/133 (Cambridge University Press, 2015-08-12)
      The objective of this study was to establish the risk factors associated with both lambing difficulty and lamb mortality in the Irish sheep multibreed population. A total of 135 470 lambing events from 42 675 ewes in 839 Irish crossbred and purebred flocks were available. Risk factors associated with producer-scored ewe lambing difficulty score (scale of one (no difficulty) to four (severe difficulty)) were determined using linear mixed models. Risk factors associated with the logit of the probability of lamb mortality at birth (i.e. binary trait) were determined using generalised estimating equations. For each dependent variable, a series of simple regression models were developed as well as a multiple regression model. In the simple regression models, greater lambing difficulty was associated with quadruplet bearing, younger ewes, of terminal breed origin, lambing in February; for example, first parity ewes experienced greater (P<0.001) lambing difficulty (1.56±0.02) than older ewes. The association between lambing difficulty and all factors persisted in the multiple regression model, and the trend in fixed effects level solutions did not differ from the trend observed in the simple regression models. In the simple regression analyses, a greater odds of lamb mortality was associated with male lambs (1.31 times more likely of death than females), lambs of very light (2 to 3 kg) and very heavy (>7.0 kg) birth weights, quadruplet born lambs and lambs that experienced a more difficult lambing (predicted probability of death for lambs that required severe and veterinary assistance of 0.15 and 0.32, respectively); lambs from dual-purpose breeds and born to younger ewes were also at greater risk of mortality. In the multiple regression model, the association between ewe parity, age at first lambing, year of lambing and lamb mortality no longer persisted. The trend in solutions of the levels of each fixed effect that remained associated with lamb mortality in the multiple regression model, did not differ from the trends observed in the simple regression models although the differential in relative risk between the different lambing difficulty scores was greater in the multiple regression model. Results from this study show that many common flock- and animal-level factors are associated with both lambing difficulty and lamb mortality and management of different risk category groups (e.g. scanned litter sizes, ewe age groups) can be used to appropriately manage the flock at lambing to reduce their incidence.