• Adding value to cull cow beef

      O'Donovan, Michael; Minchin, William; Buckley, Frank; Kenny, David; Shalloo, Laurence (Teagasc, 2009-08-01)
      This project addressed the prospects of increasing the value of cull cow beef and examined the potential of a number of different management and dietary strategies. In Ireland, the national cow herd contributes 350,000 animals to total beef production annually, which represents 22% of all cattle slaughtered (DAF, 2007). A dominant feature of beef production in Ireland is the disposal of cows from the dairy and beef industries, the time of year at which culling occurs influences the number of cows available for slaughter. Suitability of a cow for slaughter is generally not a consideration for dairy or beef farmers.
    • Additive genetic, non-additive genetic and permanent environmental effects for female reproductive performance in seasonal calving dairy females

      Kelleher, M.M.; Buckley, Frank; Evans, R.D.; Berry, Donagh P. (Teagasc (Agriculture and Food Development Authority), Ireland, 2016-09-08)
      Excellent reproductive performance (i.e. 365-day calving interval) is paramount to herd profit in seasonal-calving dairy systems. Reproductive targets are currently not being achieved in Irish dairy herds. Furthermore, most research on the genetics of reproductive performance in dairy cattle has focused primarily on lactating cows and relatively few studies have attempted to quantify the genetic contribution to differences in reproductive performance in nulliparae. The objective of the present study was to estimate the contribution of both the additive and non-additive genetic components, as well as the permanent environmental component, to phenotypic variation in the reproductive traits in nulliparous, primiparous and multiparous seasonal-calving dairy females. Reproductive phenotypes were available on up to 202,525 dairy females. Variance components were estimated using (repeatability where appropriate) linear animal mixed models; fixed effects included in the mixed models were contemporary group, parity (where appropriate), breed proportion, inter-breed specific heterosis coefficients and inter-breed specific recombination loss coefficients. Heritability of the reproductive traits ranged from 0.004 (pregnancy rate to first service) to 0.17 (age at first service in nulliparae), while repeatability estimates for the reproductive traits in cows ranged from 0.01 (calving interval) to 0.11 (pregnant in the first 42 days of the breeding season). Breed-specific heterosis regression coefficients suggest that, relative to the parental mean, a first-cross Holstein–Jersey crossbred was almost 7 days younger at first calving, had a 9-day shorter calving interval, a 6 percentage unit greater pregnancy rate in the first 42 days of the breeding season and a 3 percentage unit greater survival rate to next lactation. Heifer calving rate traits were strongly genetically correlated with age at first calving (–0.97 to –0.66) and calving rate in the first 42 days of the calving season for first parity cows (0.77 to 0.56), but genetic correlations with other cow reproductive traits were weak and inconsistent. Calving interval was strongly genetically correlated with the majority of the cow traits; 56%, 40%, and 92% of the genetic variation in calving interval was explained by calving to the first service interval, number of services and pregnant in the first 42 days of the breeding season, respectively. Permanent environmental correlations between the reproductive performance traits were generally moderate to strong. The existence of contributions from non-additive genetic and permanent environmental effects to phenotypic differences among cows suggests the usefulness of such information to rank cows on future expected performance; this was evidenced by a stronger correlation with future reproductive performance for an individual cow index that combined additive genetic, non-additive genetic and permanent environmental effects compared to an index based solely on additive genetic effects (i.e. estimated breeding values).
    • Body condition score and live-weight effects on milk production in Irish Holstein-Friesian dairy cows

      Berry, Donagh P.; Buckley, Frank; Dillon, Pat (Cambridge University Press, 2007-10)
      The objective of the present study was to quantify the relationships among body condition score (BCS; scale 1 to 5), live weight (WT) and milk production in Irish Holstein-Friesian spring calving dairy cows. Data were from 66 commercial dairy herds during the years 1999 and 2000. The data consisted of up to 9886 lactations with records for BCS or WT at least once pre-calving, or at calving, nadir or 60 days post-calving. Change in BCS and WT was also calculated between time periods. Mixed models with cow included as a random effect were used to quantify the effect of BCS and WT, as well as change in each trait, on milk yield, milk fat concentration and milk protein concentration. Significant and sometimes curvilinear associations were observed among BCS at calving or nadir and milk production. Total 305-day milk yield was greatest in cows calving at a BCS of 4.25 units. However, cows calving at a BCS of 3.50 units produced only 68 kg less milk than cows calving at a BCS of 4.25 units while cows calving at 3.25 or 3.00 BCS units produced a further 50 and 114 kg less, respectively. Cows that lost more condition in early lactation produced more milk of greater fat and protein concentration, although the trend reversed in cows that lost large amounts of condition post-calving. Milk yield increased with WT although the marginal effect decreased as cows got heavier. Milk fat and protein concentration in early lactation also increased with WT pre-calving, calving and nadir, although WT did not significantly affect average lactation milk fat concentration.
    • Comparative performance and economic appraisal of Holstein-Friesian, Jersey and Jersey×Holstein-Friesian cows under seasonal pasture-based management

      Prendiville, R.; Shalloo, Laurence; Pierce, K.M.; Buckley, Frank (Teagasc (Agriculture and Food Development Authority), Ireland, 2011)
      The objective of this study was to provide comparative performance data for Holstein- Friesian (HF), Jersey (J) and Jersey×Holstein-Friesian (F1) cows under a seasonal pasture-based management system and to simulate the effect of cow breed on farm profitability. Data for a total of 329 lactations, from 162 (65 HF, 48 J and 49 F1) cows, were available. Milk yield was highest for HF, intermediate for F1 and lowest for J, while milk fat and protein concentrations were highest for J, intermediate for F1 and lowest for HF. Yield of fat plus protein was highest for F1, intermediate for HF and lowest for J. Mean bodyweight was 523, 387 and 466 kg for HF, J and F1, respectively. Body condition score was greater for the J and F1 compared to HF. Reproductive efficiency was similar for the HF and J but superior for the F1. The Moorepark Dairy Systems Model was used to simulate a 40 ha farm integrating biological data for each breed group. Milk output was highest for systems based on HF cows. Total sales of milk solids and, consequently, milk receipts were higher with J and F1 compared to HF. Total costs were lowest with F1 cows, intermediate with HF and highest with J. Overall farm profitability was highest with F1 cows, intermediate with HF and lowest with J. Sensitivity analysis of milk price, fat to protein price ratio and differences in cost of replacement heifers showed no re-ranking of the breed groups for farm profit.
    • Comparison of breed of dairy cow under grass-based spring milk production systems

      Buckley, Frank; Walsh, S.; Dillon, Pat (Teagasc, 2006-01-01)
      The objective of this study was to investigate the potential differences among different dairy cow breeds across two feeding systems on milk production, udder health, milking characteristics, body weight, body condition score, hormone parameters, ovarian function, survival and overall reproductive efficiency. The breeds investigated included Holstein-Friesian (HF), Montbéliarde (MB), Normande (NM), Norwegian Red (NRF) and Holstein- Friesian × Montbéliarde (MBX) and Holstein- Friesian × Normande (NMX). Selection within the HF breed has, until recently, been predominantly for milk production with little or no direct selection for functional traits other than those correlated with superior type. The MB and the NM have been simultaneously selected for both milk and beef production in the past. The NRF were imported as calves and come from a more balanced total merit index incorporating production and cow functionality since the early 1970s. The dairy cow breeds were grouped into blocks of two within breed groups and randomized across two spring-calving grass-based feeding systems: low concentrate feeding system (LC) and high concentrate feeding system (HC). Those on LC feeding system were offered approximately 530 kg/cow over the total lactation, while those on HC feeding system were offered approximately 1030 kg/cow.
    • Comparison of breed of dairy cow under grass-based spring milk production systems.

      Buckley, Frank; Walsh, S.; Dillon, Pat (Teagasc, 2006-01)
      The objective of this study was to investigate the potential differences among different dairy cow breeds across two feeding systems on milk production, udder health, milking characteristics, body weight, body condition score, hormone parameters, ovarian function, survival and overall reproductive efficiency. The breeds investigated included Holstein-Friesian (HF), Montbéliarde (MB), Normande (NM), Norwegian Red (NRF) and Holstein- Friesian × Montbéliarde (MBX) and Holstein- Friesian × Normande (NMX). Selection within the HF breed has, until recently, been predominantly for milk production with little or no direct selection for functional traits other than those correlated with superior type. The MB and the NM have been simultaneously selected for both milk and beef production in the past. The NRF were imported as calves and come from a more balanced total merit index incorporating production and cow functionality since the early 1970s. The dairy cow breeds were grouped into blocks of two within breed groups and randomized across two spring-calving grass-based feeding systems: low concentrate feeding system (LC) and high concentrate feeding system (HC). Those on LC feeding system were offered approximately 530 kg/cow over the total lactation, while those on HC feeding system were offered approximately 1030 kg/cow. There was no genotype by environment interaction observed for any of the milk production, BCS, BW, udder health, milking characteristics, reproductive performance or feed intake/efficiency parameters investigated. Compared to the MB and NM, all other breeds had higher total lactation milk, fat, protein and lactose yield, with the HF having the highest. Animals on the HC feeding system had higher total lactation milk, fat, protein and lactose yield. Compared to the NRF, SCS was higher for the HF, NM, MBX and NMX breed groups, while SCS of the MB was not different. The NM and MB had lower AMF compared to all breeds. The crossbreds achieved the higher AMF. The NM had the lowest PMF, while that of the crossbreds were higher compared to all breeds. Milking duration was not affected by breed. Differences between breeds for AMF, PMF and MD were not apparent after adjustment for milk yield. Animals offered a HC diet had higher AMF, PMF and MD compared to those on the LC feeding system. Somatic cell score did not differ between the feeding systems. The interaction between breed and milk yield influenced SCS, AMF, PMF and MD thus implying that for each unit increase of milk yield by breed, the response in SCS, AMF, PMF and MD was different for some breeds. The response in SCS was similar for the NRF, MBX and NMX, while MD was similar for the MB and MBX. The effect of one unit increase in daily average milk yield caused a favourable decrease in SCS; however a one unit increase in PMF and MD did not influence SCS. No interactions were observed for breed with any milking characteristic on SCS. The HF had the lowest BCS, the MB and NM the highest, while the NRF, MBX and NMX were intermediate. The NRF had the lowest BW; the NM had the highest while the other breeds were intermediate. The NRF had increased likelihood of SR24, PREG1, PREG42 and FINALPR and greater survival compared to the HF. Both MBX and NMX had shorter CSI and CCI and were more likely to be pregnant at the end of the breeding season, thus had higher survival rates compared to the HF; however heterosis estimates for these traits was not significant, likely due to the small data size. Feed system did not influence reproductive performance of the different breeds. Breed of dairy cow did not influence any of the ovarian parameters studied. Breed of dairy cow did not influence insulin or IGF-1 concentrations at any sampling period. Breed significantly effected gestation length, calf birth weight and calving ease score. The NRF had the shortest gestation, lightest calves and least calving difficulty. Genotype had a significant effect on estimated dry matter intake, being highest with the HF, MBX, NMX and lowest with NM and NRF. Genotype also had a significant effect on yield of milk solids per kg of DMI. The highest yield of milk solids per kg of DMI was achieved with the NRF, HF and MBX. Comparisons between genotypes reveal that estimated residual feed intake estimates were lowest (most favourable) for the NRF, compared to other genotypes with the exception of HF.
    • Dairy cattle breeding objectives combining production and non-production traits for pasture based systems in Ireland.

      Berry, Donagh P.; Buckley, Frank; Dillon, Pat; Veerkamp, R.F. (Teagasc, 2005-11-01)
      The objectives of this study were: 1) to estimate genetic (co) variances among body condition score, body weight, milk production, linear type traits and fertility, and 2) to investigate the presence of genotype by environment interactions for milk production, body condition score, and body weight, in Irish grass based seasonal calving herds. Genetic parameters were estimated from a potential 8928 primiparous and multiparous Holstein-Friesian cows over two years (1999 and 2000). Heritability estimates for body condition score (BCS) and body weight (BW) were found to be moderate to high; estimates ranged from 0.27 to 0.51 for BCS, and from 0.39 to 0.61 for BW. Heritability estimates for BCS change and BW change at different stages of lactation were all less than 0.11. Heritability for the linear type traits varied from 0.11 to 0.43. Phenotypic and genetic correlations between BCS and BW at the same stage of lactation were all close to 0.50 indicating that approximately 25% of the genetic and phenotypic variation in BW may be attributed to differences in BCS. Genetic correlations between BCS and milk yield tended to be negative (-0.14 to –0.51) and genetic correlations between BW and milk yield were close to zero (-0.07 to 0.09). However, the genetic correlations between BW adjusted for differences in BCS were positive (0.15 to 0.39). Genetic correlations between BCS and the fertility traits investigated were all favourable, indicating that cows with a superior genetic merit for BCS are on average likely to be served sooner, receive less services and have higher pregnancy rates. The genetic correlations between linear type traits and milk yield indicate that selection for milk production has resulted in taller, deeper cows that tend to be more angular and have less body condition. Genetically these cows are predisposed to inferior reproductive efficiency. Moderate genetic correlations were found between some of the linear type traits investigated and somatic cell count. A comparison of BCS, as recorded by Teagasc personnel (scale 1-5) and Holstein herd-book classifiers (scale 1-9) indicated consistency between the two sources. Phenotypic and genetic correlations of 0.54 and 0.86, respectively, were observed between the two measurement sources on the same animals. Genotype by environment interactions, were found for milk yield across different silage quality environments, and for BCS across different herd-year milk yield, concentrate, grazing severity and silage quality environments.
    • Detection of abnormal recordings in Irish milk recorded data

      Quinn-Whelton, N.; Killen, L.; Guinee, Timothy P.; Buckley, Frank (Teagasc, Oak Park, Carlow, Ireland, 2007)
      The objective of this study was to detect abnormal recordings of milk yield, fat concentration and protein concentration in Irish milk-recorded data. The data consisted of 14,956 records from both commercial and experimental herds with 92% of the recordings recorded manually and the remainder recorded electronically. The method used in this paper was a modified version of the method employed by the Animal Improvement Programs Laboratory in Maryland, USA and conformed with the guidelines outlined by the International Committee of Animal Recording. The results illustrate the effectiveness of detecting abnormal recordings in Irish milk records. The method described in this paper, defines the upper and lower limits for each production trait and these limits along with the slope parameters were used to determine if a recording was abnormal or not. Three percent of milk yield recordings, 5% of fat concentration recordings and less than 1% of protein concentration recordings were found to be abnormal. The proportion of values declared abnormal in manually recorded and electronically recorded data were examined and found to be significantly different for fat concentration.
    • Effect of genotype on duodenal expression of nutrient transporter genes in dairy cows

      Waters, Sinead M.; Keogh, Kate; Buckley, Frank; Kenny, David A (Biomed Central, 2013-12-09)
      Background Studies have shown clear differences between dairy breeds in their feed intake and production efficiencies. The duodenum is critical in the coordination of digestion and absorption of nutrients. This study examined gene transcript abundance of important classes of nutrient transporters in the duodenum of non lactating dairy cows of different feed efficiency potential, namely Holstein-Friesian (HF), Jersey (JE) and their F1 hybrid. Duodenal epithelial tissue was collected at slaughter and stored at -80°C. Total RNA was extracted from tissue and reverse transcribed to generate cDNA. Gene expression of the following transporters, namely nucleoside; amino acid; sugar; mineral; and lipid transporters was measured using quantitative real-time RT-PCR. Data were statistically analysed using mixed models ANOVA in SAS. Orthogonal contrasts were used to test for potential heterotic effects and spearman correlation coefficients calculated to determine potential associations amongst gene expression values and production efficiency variables. Results While there were no direct effects of genotype on expression values for any of the genes examined, there was evidence for a heterotic effect (P < 0.05) on ABCG8, in the form of increased expression in the F1 genotype compared to either of the two parent breeds. Additionally, a tendency for increased expression of the amino acid transporters, SLC3A1 (P = 0.072), SLC3A2 (P = 0.081) and SLC6A14 (P = 0.072) was also evident in the F1 genotype. A negative (P < 0.05) association was identified between the expression of the glucose transporter gene SLC5A1 and total lactational milk solids yield, corrected for body weight. Positive correlations (P < 0.05) were also observed between the expression values of genes involved in common transporter roles. Conclusion This study suggests that differences in the expression of sterol and amino acid transporters in the duodenum could contribute towards the documented differences in feed efficiency between HF, JE and their F1 hybrid. Furthermore, positive associations between the expression of genes involved in common transporter roles suggest that these may be co-regulated. The study identifies potential candidates for investigation of genetic variants regulating nutrient transport and absorption in the duodenum in dairy cows, which may be incorporated into future breeding programmes.
    • The effect of Holstein-Friesian genotype and feeding system on selected performance parameters of dairy cows on grass-based systems of milk production in Ireland.

      Dillon, Pat; O'Connor, P.; McCarthy, S.; Shalloo, Laurence; Linnane, M.; Berry, Donagh P.; Buckley, Frank; Mee, John F; Horan, Brendan (Teagasc, 2006-01-01)
      The overall objective of this project was to assess, the effect of strain of Holstein-Friesian dairy cow, pasture-based feed system (FS) and their interaction on animal performance in terms of milk productivity and lactation profile, body weight (BW), body condition score (BCS), feed intake and energy balance (EB), reproductive performance and overall economic profitability.
    • Empirical algebraic modelling of lactation curves using Irish data

      Quinn, N.; Killen, L.; Buckley, Frank (Teagasc (Agriculture and Food Development Authority), Ireland, 2005)
      The purpose of this study was to find a well-fitting, robust, single-equation model to describe the shape of lactation curves for Irish dairy cows. The suitability of a number of algebraic models that depict lactation curves was examined, using Irish test day data. The analysis was carried out on a total of 14,956 lactation records from commercial and experimental herds and included both autumn and spring calving animals. ‘Goodness of fit’ and adherence of the various models to the assumptions of regression analysis were examined. Multicollinearity posed a severe problem in the application of the best-fit model but omitting one of the variables from the estimation procedure reduced this effect. The modified model, referred to as the Ali-B model, is a single equation model that can be easily updated and incorporated into computer code. This is in contrast with the Standard Lactation Curve (SLAC) method, a method of interpolation, which is currently used by the Irish industry. The effects of seasonal factors on milk production were estimated and added to the Ali-B model to create a production profile for cows calving in specific months. The Ali-B model provided an acceptable level of accuracy in representing the shape of the lactation curve for Irish dairy cows, and can be easily modified for different environmental scenarios.
    • An Evaluation of High Genetic Merit Cows Using Forage and Pasture-based Systems.

      Dillon, Pat; Buckley, Frank (Teagasc, 1999-09-01)
      The rate of genetic improvement in Ireland up until the mid-80’s was low (approx. 0.5% per year) compared to North America where genetic merit for milk production was increasing by 1.5% per year (Funk, 1993). Since 1985 the rate of genetic improvement increased markedly to about 1.5% per year in 1992 (Coffey, 1992). This high rate of genetic progress has mostly been achieved through the importation of North American and European genetics. The relative merit of these sires has been obtained from the performance of their progeny in systems of milk production which differ greatly from those operated in Ireland. The term “high genetic index” (HGI) is used to describe a cow, which as a result of selection, is generally predisposed to produce significantly more milk than a cow of lower merit status. Studies from New Zealand have shown that cows of high “genetic index” at pasture, produce more milk (20 to 40%), consume more herbage (5 to 20%), were more efficient convertors of food into milk (10 to 15%) than lower merit cows (Holmes, 1988). However, these “high” genetic index cows would be considered “low” when compared to present-day genetics. Recent results from Langhill (Veerkamp et al., 1994) have shown that increasing genetic index results in major increases in feed efficiency, reflecting increases in milk yield with cows fed indoors on silage/concentrate diets. There is little information available on the performance of present-day HGI dairy cows, on seasonal calving, grass-based systems of milk production
    • Gastrointestinal tract size, total-tract digestibility, and rumen microflora in different dairy cow genotypes

      Beecher, Marion; Buckley, Frank; Waters, Sinead M.; Boland, T. M.; Enriquez-Hidalgo, D.; Deighton, M. H.; O'Donovan, Michael; Lewis, Eva (Elsevier Inc and American Dairy Science Association, 2014-04-03)
      The superior milk production efficiency of Jersey (JE) and Jersey × Holstein-Friesian (JE × HF) cows compared with Holstein-Friesian (HF) has been widely published. The biological differences among dairy cow genotypes, which could contribute to the milk production efficiency differences, have not been as widely studied however. A series of component studies were conducted using cows sourced from a longer-term genotype comparison study (JE, JE × HF, and HF). The objectives were to (1) determine if differences exist among genotypes regarding gastrointestinal tract (GIT) weight, (2) assess and quantify whether the genotypes tested differ in their ability to digest perennial ryegrass, and (3) examine the relative abundance of specific rumen microbial populations potentially relating to feed digestibility. Over 3 yr, the GIT weight was obtained from 33 HF, 35 JE, and 27 JE × HF nonlactating cows postslaughter. During the dry period the cows were offered a perennial ryegrass silage diet at maintenance level. The unadjusted GIT weight was heavier for the HF than for JE and JE × HF. When expressed as a proportion of body weight (BW), JE and JE × HF had a heavier GIT weight than HF. In vivo digestibility was evaluated on 16 each of JE, JE × HF, and HF lactating dairy cows. Cows were individually stalled, allowing for the total collection of feces and were offered freshly cut grass twice daily. During this time, daily milk yield, BW, and dry matter intake (DMI) were greater for HF and JE × HF than for JE; milk fat and protein concentration ranked oppositely. Daily milk solids yield did not differ among the 3 genotypes. Intake capacity, expressed as DMI per BW, tended to be different among treatments, with JE having the greatest DMI per BW, HF the lowest, and JE × HF being intermediate. Production efficiency, expressed as milk solids per DMI, was higher for JE than HF and JE × HF. Digestive efficiency, expressed as digestibility of dry matter, organic matter, N, neutral detergent fiber, and acid detergent fiber, was higher for JE than HF. In grazing cows (n = 15 per genotype) samples of rumen fluid, collected using a transesophageal sampling device, were analyzed to determine the relative abundance of rumen microbial populations of cellulolytic bacteria, protozoa, and fungi. These are critically important for fermentation of feed into short-chain fatty acids. A decrease was observed in the relative abundance of Ruminococcus flavefaciens in the JE rumen compared with HF and JE × HF. We can deduce from this study that the JE genotype has greater digestibility and a different rumen microbial population than HF. Jersey and JE × HF cows had a proportionally greater GIT weight than HF. These differences are likely to contribute to the production efficiency differences among genotypes previously reported.
    • Genetic relationships among linear type traits, milk yield, body weight, fertility and somatic cell count in primiparous dairy cows

      Berry, Donagh P.; Buckley, Frank; Dillon, Pat; Evans, Ross D; Veerkamp, R. F. (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
      Phenotypic and genetic (co)variances among type traits, milk yield, body weight, fertility and somatic cell count were estimated. The data analysed included 3,058 primiparous spring-calving Holstein-Friesian cows from 80 farms throughout the south of Ireland. Heritability estimates for the type traits varied from 0.11 to 0.43. Genetic correlations among some type traits were very strong and may indicate the possibility of reducing the number of traits assessed on each animal; the genetic correlation between angularity and body condition score was –0.84. Genetic correlations between all type traits (except body condition score, udder depth and teat length) and milk yield were positive and ranged from 0.08 to 0.69. The possibility of selecting for body weight may be achievable within a national progeny-testing programme using type traits within a selection index. Moderate to strong genetic correlations existed between some type traits and the various fertility measures and somatic cell count indicating the opportunity of indirect selection for improved fertility and health of animals using type traits within a selection index; however, the standard errors of some of the genetic correlations were large and should thus be treated with caution. Genetically taller, wider, deeper, more angular cows with tighter, stronger, shallower udders were predisposed to have inferior pregnancy rates to first service and require more services.
    • Genetic relationships among linear type traits, milk yield, body weight, fertility and somatic cell count in primiparous dairy cows

      Berry, Donagh P.; Buckley, Frank; Dillon, Pat; Evans, Ross D; Veerkamp, Roel F (Teagasc (Agriculture and Food Development Authority), Ireland, 2004)
      Phenotypic and genetic (co)variances among type traits, milk yield, body weight, fertility and somatic cell count were estimated. The data analysed included 3,058 primiparous spring-calving Holstein-Friesian cows from 80 farms throughout the south of Ireland. Heritability estimates for the type traits varied from 0.11 to 0.43. Genetic correlations among some type traits were very strong and may indicate the possibility of reducing the number of traits assessed on each animal; the genetic correlation between angularity and body condition score was –0.84. Genetic correlations between all type traits (except body condition score, udder depth and teat length) and milk yield were positive and ranged from 0.08 to 0.69. The possibility of selecting for body weight may be achievable within a national progeny-testing programme using type traits within a selection index. Moderate to strong genetic correlations existed between some type traits and the various fertility measures and somatic cell count indicating the opportunity of indirect selection for improved fertility and health of animals using type traits within a selection index; however, the standard errors of some of the genetic correlations were large and should thus be treated with caution. Genetically taller, wider, deeper, more angular cows with tighter, stronger, shallower udders were predisposed to have inferior pregnancy rates to first service and require more services.
    • Insemination factors affecting the conception rate in seasonal calving Holstein-Friesian cows

      Buckley, Frank; Mee, John F; O'Sullivan, Kathleen; Evans, Ross D; Berry, Donagh P.; Dillon, Pat (EDP Sciences, 2003-11)
      Differences in conception rate to first service between artificial inseminations (AI) carried out by commercial AI operators (CAI) or do-it-yourself operators (DIY), between natural service (NAT) and AI, between different AI sires, and between fresh and frozen-thawed semen, on Irish commercial dairy farms, were studied using logistic regression. The study comprised 12 933 potential first inseminations from 77 spring-calving dairy herds. The data were recorded during 1999 and 2000. Amongst the total, 4 394 cows had repeated records across the two years. Adjustment variables included: herd, year, parity, calving period, calving to service interval, herd size, proportion of North American Holstein-Friesian genes, peak milk yield, semen fresh or frozen-thawed status, AI sire and a cow history variable to account for the correlation structure that may exist between performance records of cows present in both years of the study. Interactions of interest were tested but were non-significant. No significant association was observed between the category of AI operator and the likelihood of conception rate to first service (PREG1). The variation in PREG1 observed within the category of operator (CAI and DIY) was investigated using the Levene test for homogeneity of variance. There was no difference between the level of variation observed within CAI and DIY operators. There were significant differences in the likelihood of PREG1 between different AI sires. Amongst the 40 most commonly used AI sires, 3 sires had a lower likelihood of PREG1 (P < 0.05) when compared to the reference AI sire (sire with PREG1 similar to the mean of the group). There was a tendency for a reduced likelihood of PREG1 with the use of fresh semen compared to frozen-thawed semen ( , P = 0.067). Amongst the adjustment variables in the model, those significantly associated with the likelihood of PREG1 included the herd, calving period, calving to first service interval and peak milk yield. No significant difference in the likelihood of PREG1 was observed between AI and NAT.
    • Major management factors associated with the variation in reproductive performance of Irish dairy herds

      Buckley, Frank; Dillon, Pat; Mee, John F (Teagasc, 2007-01-01)
      The results highlight the importance of BCS in achieving good reproductive performance. The likelihood of reproductive success was best predicted by BCS around the time of breeding and, for cows calving in good BCS (3.0 or greater) the level of BCS loss between calving and first service. A low BCS pre-calving (<2.75) was associated with prolonged calving to first service, and calving to conception intervals. Very high BCS pre-calving (>3.5) results in excessive BCS loss (>0.5) post-calving. On the basis of these findings a pre-calving BCS of no greater than 3.25 is a sensible target for pasture-based spring calving systems in Ireland. It is necessary to maintain BCS at 2.75 or greater during the breeding season, and loss of body condition between calving and first service should be restricted to 0.5 BCS units.
    • Modelling fat and protein concentration curves for Irish dairy cows

      Quinn, N.; Killen, L.; Buckley, Frank (Teagasc, Oak Park, Carlow, Ireland, 2006)
      The objective of this study was to acquire a well-fitting, single-equation model that would represent the fat and protein concentration curves of milk from Irish dairy cows. The dataset consisted of 16,086 records from both spring and autumn calving cows from both experimental and commercial herds. Many models cited in the literature to represent milk yield were examined for their suitability to model constituent curves. Models were tested for goodness-of-fit, adherence to the assumptions of regression analysis, and their ability to predict total fat and protein concentration for an entire lactation. Wilmink’s model best satisfied these criteria. It had the best Mean Square Prediction Error (goodness-of-fit) value, it satisfied the assumptions of regression analysis (multicollinearity, heteroskedasticity, autocorrelation and normality of distribution), and it predicted the actual concentration of the constituents to within 0.01 percentage point.
    • Prediction of cull cow carcass characteristics from live weight and body condition score measured pre slaughter

      Minchin, W.; Buckley, Frank; Kenny, David A.; Keane, Michael G.; Shalloo, Laurence; O'Donovan, Michael (Teagasc, Oak Park, Carlow, Ireland, 2009)
      A study was conducted to provide information on the degree of carcass finish of Irish cull cows and to investigate the usefulness of live animal measurements for the prediction beef breeds (albeit with a moderate R2 value compared to the carcass weight prediction) using objective, non-intrusive and easily measured live animal measurements, should be of benefit to farmers finishing cull cows in Ireland. of cull cow carcass characteristics. Live weight (LW) and body condition score (BCS) were recorded on cows entering an Irish commercial slaughter facility between September and November, 2005. Data pertaining to sire breed, age and carcass characteristics were collected and subsequently collated for each cow. For analysis, cows (n = 2163) were subdivided into three breed categories: dairy breed sired by Holstein/ Friesian (FR), sired by early-maturing beef breeds (EM) and sired by late-maturing beef breeds (LM). The proportion of cows slaughtered at the desired (TARGET) carcass standard (cold carcass weight ≥ 272 kg, carcass conformation class ≥ P+ and carcass fat class ≥ 3) was low (on average 0.30), but did differ (P < 0.001) between the dairy and beef breed categories (0.22, 0.47 and 0.53 for FR, EM and LM categories, respectively). Regression procedures were used to develop equations to predict cold carcass weight, carcass conformation score, carcass fat score and proportion in the TARGET category from LW and BCS. Equations predicting cold carcass weight had high R2 values for all breed categories (0.81, 0.85 and 0.79 for the FR, EM and LM, respectively). Equations predicting carcass fatness had moderate R2 values for the beef breed categories (0.65 and 0.59 for the EM and LM, respectively). Equations predicting carcass conformation and the TARGET category yielded lower R2 values. The successful prediction of carcass weight for all breed categories and of carcass fatness for the
    • 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.