Sire Type Research Articles

Effect of sire type and a by-product based diet on performance and meat quality in growing-finishing pigs

For many years, pig production has focused on maximizing performance by selecting for maximal muscle growth and feeding diets that allow the animals to express their genetic potential. However, it is unclear whether this selection for muscle deposition has affected the capacity of pigs to cope with by-product-based diets, which rely on fat as the primary energy source instead of starches and sugars. Therefore, an experiment was set up to investigate if different types of boars affect how their progeny cope with alternative ingredients in the diet, with a possible need for adapted breeding schemes. Two types of boars within the Piétrain sire line were used based on either a high or low estimated breeding value for daily feed intake (HFI: high feed intake, low feed intake). When their progeny reached 14 weeks of age, two dietary strategies were compared: a control (CON) vs a by-product-based diet high in fat and fiber (HFF). The CON diet was mainly based on cereals (corn, wheat, barley) and soybean meal. The HFF diet was formulated to contain the same net energy, CP and digestible amino acid levels without any cereals or soybean meal. In total 192 animals were included in the experiment (48 animals/type of boar/diet) and performance, digestibility, carcass and meat quality were compared. None of the parameters showed a significant interaction (P < 0.05) between the type of boar and diet, suggesting that shifting to diets that are less prone to feed-food competition is equally feasible in different types of pigs. Type of boar did affect performance, carcass quality and intramuscular fat content. HFI pigs showed higher daily feed intake (DFI) and daily gain (P < 0.001), with no significant difference in feed conversion ratio (P = 0.205), lower carcass quality (P < 0.001) and higher intramuscular fat content (P = 0.030). For both boar types, pigs fed the CON diet performed better, with a higher daily gain (P = 0.028), DFI (P = 0.011) and dressing yield (P = 0.009) and better digestibility (P < 0.001), but without differences in feed conversion ratio or meat quality. In conclusion, there was no indication that pigs differing in feed intake capacity cope differently with a high-fat, high-fiber diet based on by-products. Different types of pigs may cope well with diets that are less prone to feed-food competition.

Effect of sire fecal egg count estimated breeding value on Katahdin lamb parasite resistance in pasture-based system

Significant genetic variability exits within sheep breeds for gastrointestinal nematode (GIN) resistance. Therefore, selection may be an important tool to combat anthelmintic resistance in GIN populations. To better understand the effect of selection based on the fecal egg count (FEC) estimated breeding value (EBV) on lamb GIN resistance in a pasture-based system, a divergent mating scheme was established. Over two years, Katahdin rams with exceptionally high (High FEC; n = 5) or low (Low FEC, n = 5) FEC EBV were mated to random groups of Katahdin ewes at the Southwest Virginia Agricultural Research and Extension Center (Glade Spring, VA). Lambs were born mid-March and managed as one contemporary group (Weaning: June 4). In Year 1 (YR1), FEC was collected on all lambs June 26 with no prior anthelmintic treatment. In Year 2 (YR2), beginning at 60 days of age, body weights and FAMACHA scores were collected weekly and FEC biweekly. Anthelmintic administration occurred based on FAMACHA ≥ 3 in YR2. Lamb survival determination excluded first 7 days of age. Statistical analysis was performed using SAS (SAS Institute, Cary, NC) with fixed effects of sire type. Lamb FEC EBV corresponded to sire type validating the mating scheme. Lamb FEC was similar and variable prior to and shortly after weaning. After this point, High FEC-sired lambs had greater FEC compared to Low FEC-sired lambs (P < 0.05) and anthelmintic treatment corresponded to FEC EBV type (P < 0.05). In YR1, death losses were greater for High FEC-sired lambs (P < 0.05) and those lambs that died had greater FEC EBV than those that survived (P < 0.05). In YR2, post-weaning FEC EBV difference between High FEC-sired lambs that survived to 120 days of age and those that died was significant (73% vs. 138%, P < 0.01). Therefore, selection for improved GIN resistance using FEC EBV is effective and the FEC EBV is also associated with lamb survival in a pasture-based system.

Chinese Consumer Assessment of Australian Sheep Meat Using a Traditional Hotpot Cooking Method

Hotpot is a widely popular cooking method for sheepmeat in China. This study measured the sensory responses of 720 untrained Chinese consumers to Australian sheepmeat cooked using a hotpot technique with methods based on Meat Standards Australia protocols. Shoulder and leg cuts of 108 lambs and 109 yearlings were scored on tenderness, juiciness, flavour and overall liking with linear mixed effects models used to analyse the influence of muscle type and animal factors on these scores. On average, shoulder cuts were more palatable than legs cuts for all sensory traits (p < 0.01) and lambs compared to yearlings (p < 0.05). Intramuscular fat and muscularity were identified as strong drivers of eating quality (p < 0.05), with greater palatability for both cuts as intramuscular fat increased (range 2.5 to 7.5%), and muscularity decreased (as measured through loin weight adjusted for hot carcase weight). Consumers were unable to detect differences between animal sire type and sex in sheepmeat hotpot. These findings suggest shoulder and leg cuts performed comparatively well in hotpot compared to previously tested sheepmeat cooking methods and emphasise the importance of balanced selection for quality and yield traits to ensure that consumer satisfaction is maintained.

Investigation of Reciprocal Cross Effects in F2 Nellore–Angus Calves

The objectives of this study were to analyze calf performance traits and sex ratio frequencies in reciprocal Bos indicus–Bos taurus F2 Nellore–Angus calves (n = 539). The F2 calves were produced using reciprocal Angus-sired (AN) and Nellore-sired (NA) F1 sires and F1 dams, resulting in four F2 cross types. Calf weight traits were analyzed using mixed models. Deviations from 50% calf sex ratios were tested against expected binomial thresholds. Dam type influenced Julian birth date (p &lt; 0.05) with calves from AN cows born 5 to 6 days earlier than calves from NA cows. Sire type and dam type affected birth weight (p &lt; 0.05) with calves from NA parents approximately 2.5 kg heavier than those from AN parents; weaning weight did not differ for parent F1 type. However, an interaction between sire and dam types affected weaning weight (p = 0.038) where AN x AN calves were 5 to 8 kg lighter than other crosses. Sire type influenced calf sex distribution at birth (p = 0.036) and at weaning (p = 0.026) with NA sires producing over 66% male calves. These results suggest birth weight reciprocal differences due to parental line of descent typically observed among F1 Bos indicus–Bos taurus crosses can persist in subsequent generations.

Crossbreeding beef sires to dairy cows: cow, feedlot, and carcass performance.

Genetic and reproductive advancements in the dairy industry, volatile milk markets, and beef packer restrictions on dairy carcasses have increased the popularity of crossbreeding beef sires to dairy cows in the United States. This observational study aimed to understand performance of dairy cows bred to beef sires and feedlot and carcass performance of crossbred beef × dairy cattle. For dairy cow performance, archived records from two dairies representing two successive lactations were evaluated in cows (Dairy A: n = 72/group; Dairy B: n = 456/group) representing 1) All Dairy, where previous sire type of conception was Holstein for both lactations, or 2) Beef on Dairy, where previous sire type of conception was Holstein for the preceding lactation and a beef breed for the subsequent lactation. For feedlot performance, closeout data from pens (n = 26/cattle type) of beef and beef × dairy steers and heifers were evaluated. For carcass performance, individual carcass data were compared between conventional beef (n = 966), beef × dairy (n = 518), and Holstein (n = 935) steers sampled across a variety of processing facilities, harvest lots, and geographical regions. Cow lactation performance was minimally impacted by sire type of previous conception. Cows conceived to beef sires exhibited a 2 to 3 d greater (P < 0.01) gestation length than cows conceived to Holstein sires. Beef × dairy cattle were not largely different in weight gain at the feedlot but exhibited 1-unit lesser (P < 0.01) dressing percentage than beef cattle. Beef × dairy carcasses possessed 18% lesser (P < 0.05) 12th rib fat thickness than beef cattle and 5% greater (P< 0.05) ribeye area than dairy cattle. Additionally, beef cattle produced nearly double (P < 0.05) the percentage of yield grade 4 carcasses produced by beef × dairy and Holstein cattle.

Sire Breed, Litter Size, and Environment Influence Genetic Potential for Lamb Growth When Using Sire Breeding Values.

Simple SummaryPrevious studies have demonstrated a reduced response to sire growth breeding values when there is poor ewe nutrition, resulting in lighter lambs. The current study has demonstrated that production factors which influence lamb growth, such as birth type, rear type, or sire breed, have a similar effect. The reduced growth in lambs is quantified in this study to provide lamb producers with realistic expectations of lamb growth, when high growth sires are used in combination with production factors which influence growth.Lamb growth can be optimised with genetic selection using sire Australian sheep breeding values, however, breeding value expression has been shown to be reduced with poor nutrition. It was therefore hypothesised that the genetic potential for lamb growth would also be reduced, where production factors such as multiple births limit growth. Live weights at birth, weaning, and post-weaning were collected from more than 18,000 lambs produced over five years and eight locations of the Sheep Cooperative Research Centre Information Nucleus Flock experiment, and the impact of environment, production factors, and genotype was determined using mixed effects regression. The genetic potential for lamb growth was moderated by environment, multiple births, and sire type (p < 0.05). Twin lambs achieved 76% of the expected weight gain at weaning and 58% post-weaning. For triplet lambs weight gains were drastically less at approximately 30% of the expected gain at the same time points. Lambs born to maternal sires consistently had the poorest response to genetic selection, achieving approximately half the expected weight gain. Hence, producers need to temper expectations for growth based on genetic selection, or employ mitigation strategies such as precision feeding, the use of alternate breeds, or place emphasis on the genetic merit of other desirable traits.

30 Calf Performance and Sex Ratios in Second Generation Reciprocal Nellore-angus Crosses

Abstract The objectives of this study were to analyze calf weight and sex distribution differences in reciprocal F2 Nellore-Angus calves (n = 559) born 2010–2015 and calves out of these F2 females through 4 yr age (n = 469) born 2012–2018. The F2 animals were produced by 4 F1 parent type combinations from Nellore-sired (NA) vs. Angus-sired (AN) sires and dams. Weight traits were analyzed using mixed models, and sex distribution was analyzed through PROC GLIMMIX in SAS. Sire type and dam type affected birth weight (P &amp;lt; 0.05) but not weaning weight of the F2 calves. However, the interaction between sire type and dam type accounted for weaning weight differences (P = 0.038). Birth weight averaged 3.5 kg heavier from NA vs. AN sires, and 2.4 kg heavier from NA vs. AN dams. Weaning weight displayed a different pattern than observed in birth weight with the heaviest calves being NAAN (224.5 ± 3.7 kg) and lightest being ANAN (215.9 ± 3.9 kg). Sire type accounted for important variation (P = 0.036) in the calf sex distribution at birth among F2 calves. Percentage males at birth exceeded the expected ratio for NA-sired calves (66.6%, n = 168) but not for AN-sired calves (49.9%, n = 105). The sire and dam type main effects in the F2 females did not influence weight traits or sex distribution in their calves (from predominantly Angus sires). However, the interaction of sire type x dam type x sex showed a trend in birth weight (P = 0.080) and importance for weaning weight (P = 0.010) where only from ANNA and NANA dams were males heavier than females. These results suggest that some of the calf weight reciprocal differences typically observed among F1 Bos indicus-Bos taurus crosses can persist in later generations.

91 Assessing Variability of Herd Sire Economic Value for Commercial Operations

Abstract Number of calves (n = 596) and weaning calf value (n = 574) from natural service, multi-sire breeding groups were evaluated in a crossbred research herd. Sires and dams that were F1 crosses of Angus (A) and Nellore (N) were mated annually during 60 to 90-day breeding seasons to produce spring-born calves in 2009–2015. Numbers of sires used annually varied from 5 to 9; numbers of females exposed per bull ranged from 14 to 22 across years. Bulls were pastured together throughout the year as well as breeding seasons. Sires were identified based on calf DNA genotyping. Calf number, birth date, birth weight, weaning weight, and economic value were determined per bull annually. Calf value was based on weaning weight and reported prices for respective weaning dates. Calf prices were calculated separately for steers and heifers relative to 22.7 kg (50 lb) increments for corresponding weight class and year. Mixed model analyses were conducted that included fixed categorical effects of calf birth year, type of F1 sire (A-sired vs. N-sired), sire nested within type, calf sex, and the interaction of F1 sire type with calf sex. Covariates of Julian birth date and calf weaning age were included for birth weight and weaning weight, respectively. Large differences in calf numbers and performance (P &amp;lt; 0.05) were observed. Weaned calves produced annually per sire ranged from 0 to 48. Average annual calf performance per sire ranged from 28.4 to 50.8 kg for birth weight and 146.5 to 249.0 kg for weaning weight. Annual economic value per sire ranged from $0 to $30,870 when considering half of each calf’s value as attributed to the sire. Commercial producers should consider potential sire variability for calf numbers, birth date distribution, and ratio of female-to-male calves in combination with calf performance for economic assessments.

Comparison of reproductive performance of AI- and natural service-sired beef females under commercial management.

The objective of this study was to assess differences in reproductive performance of natural service and artificial insemination (AI) sired beef females based on pregnancy outcomes, age at first calving, and calving interval. Data were sourced from 8,938 cows sired by AI bulls and 3,320 cows sired by natural service bulls between 2010 and 2017. All cows were in a commercial Angus herd with 17 management units located throughout Virginia and represented spring and fall calving seasons. All calves were born to dams managed with estrus synchronization. Pregnancy was analyzed with generalized linear mixed models and other reproductive measures with linear mixed models in R. Six models were evaluated with the dependent variables of pregnancy status at the first diagnosis, pregnancy status at the second diagnosis, pregnancy type (AI or natural service) at the first diagnosis, pregnancy type at the second diagnosis, calving interval, and age at first calving. Independent variables differed by model but included sire type of the female (AI or natural service), prebreeding measures of age, weight, and body condition score, postpartum interval, sex of the calf nursing the cow, and management group. No differences were observed between AI- and natural service-sired females based on pregnancy status at first and second pregnancy diagnosis (P > 0.05). Sire type was only found to be significant for age at first calving (P < 0.05) with AI-sired females being 26.6 ± 1.6 d older at their first calving, which was expected because AI-sired females were born early in the calving season making them older at breeding. Surprisingly, age and body condition score were not significant predictors of pregnancy (P > 0.05). Body weight at breeding was not significant for pregnancy (P > 0.05) but was significant for age at first calving (P < 0.05). These data suggested that lighter heifers calved earlier which contradicts our original hypothesis. Overall, commercial Angus females sired by AI or natural service bulls had similar reproductive performance. Factors that were commonly associated with reproductive success were not significant in this commercial Angus herd managed with estrus synchronization. Given the size of these data, the importance of body condition, age, and weight should be reassessed in modern genetics and management practices.

Factors influencing parentage ratio in canine dual-sired litters

Breeding a bitch with two different sires during a single estrous cycle has the potential to facilitate rapid genetic gain and improve reproductive performance within a canine breeding colony. There is limited data regarding the factors that contribute to the success of dual-sired litters in domestic dogs, and only anecdotal evidence suggesting that these litters rarely produce offspring from more than one sire. The objective of this prospective clinical study was to investigate multiple factors that likely affect the success of dual-sired litters on whelping rate, litter size and parentage ratio. These factors include: timing of artificial insemination (AI), order of sires, number of AI’s per cycle, semen type, sperm quality and age of sire and bitch. Data collected over a 10 year period from twenty-nine estrous cycles (28 individual bitches of 10 different breeds) were evaluated after an initial AI with frozen semen from the ‘genetically desired’ sire and followed up with a second AI with either fresh (n = 9) or frozen (n = 16) semen or natural mating (n = 4) from a different, ‘back up’, sire. DNA parentage of each pup born was determined by using a primary panel of 288 SNPs. The whelping rate and litter size from previous single sire inseminations per estrous cycle, in the same bitches, (n = 16) over 25 estrous cycles using either fresh (n = 4) or frozen-thawed (n = 21) semen, were analyzed as controls. Of the 29 dual-sired breedings, 26 bitches whelped (89.7%), and 8 litters (30.8%) were of mixed parentage. In the litters of mixed parentage after a dual-sired breeding, a greater proportion of the offspring were from the second sire than the first sire (73.0% and 27.0% respectively; P < 0.05). Interestingly, in litters where all pups were of single sire parentage after a dual-sired breeding, 50.0% of the offspring were by the first sire and 50.0% were by the second sire. For litters of mixed or single paternity produced by dual-sired breeding there was no difference in average litter size. However, on a per estrous cycle basis for each bitch the whelping rate (89.7% v. 76.0%.) and litter size (5.5 ± 2.5 v. 4.0 ± 2.78) of all dual-sired breedings were greater (P < 0.05) compared to previous single-sired breedings (controls) respectively. This study demonstrates that offspring of mixed parentage derived from dual-sired breedings may be achieved. Furthermore, insemination with semen from two different sires may increase the whelping rate and litter size, which is an important consideration when using genetically valuable, or older individuals with potentially reduced fertility.

Dual energy X-ray absorptiometry precisely and accurately predicts lamb carcass composition at abattoir chain speed across a range of phenotypic and genotypic variables

Dual energy X-ray absorptiometry (DEXA) is an imaging modality that has been used to predict the computed tomography (CT)-determined carcass composition of multiple species, including sheep and pigs, with minimal inaccuracies, using medical grade DEXA scanners. An online DEXA scanner in an Australian abattoir has shown that a high level of precision can be achieved when predicting lamb carcass composition in real time. This study investigated the accuracy of that same online DEXA when predicting fat and lean percentages as determined by CT over a wide range of phenotypic and genotypic variables across 454 lambs over 6 kill groups and contrasted these results against the current Australian industry standard of grade-rule (GR) measurements to grade carcasses. Lamb carcasses were DEXA scanned and then CT scanned to determine CT Fat % and CT Lean %. All phenotypic traits and genotypic information, including Australian Sheep Breeding Values, were recorded for each carcass. Residuals of the DEXA predicted CT Fat % and Lean %, and the actual CT Fat % and Lean % were calculated and tested against all phenotypic and genotypic variables. Excellent overall precision was recorded when predicting CT Fat % (R2 = 0.91, RMSE = 1.19%). Small biases present for sire breed, sire type, dam breed, hot carcass weight and c-site eye muscle area could be explained by a regression paradox; however, biases among kill group (−0.73% to 1.01% for CT Fat %, −1.48% to 0.76% for CT Lean %) and the Merino sire type (0.36% for CT Fat %, −0.73% for CT Lean %) could not be explained by this effect. Over the large range of phenotypic and genotypic variation, there was excellent precision when predicting CT Fat % and CT Lean % by an online DEXA, with only minor biases, showing superiority to the existing Australian standard of GR measurements.

Updating maintenance energy requirement for the current sheep flocks and the associated effect of nutritional and animal factors

There is evidence indicating that using the current UK energy feeding system to ration the present sheep flocks may underestimate their nutrient requirements. The objective of the present study was to address this issue by developing updated maintenance energy requirements for the current sheep flocks and evaluating if these requirements were influenced by a range of dietary and animal factors. Data (n = 131) used were collated from five experiments with sheep (5 to 18 months old and 29.0 to 69.8 kg BW) undertaken at the Agri-Food and Biosciences Institute of the UK from 2013 to 2017. The trials were designed to evaluate the effects of dietary type, genotype, physiological stage and sex on nutrient utilization and energetic efficiencies. Energy intake and output data were measured in individual calorimeter chambers. Energy balance (Eg) was calculated as the difference between gross energy intake and a sum of fecal energy, urine energy, methane energy and heat production. Data were analysed using the restricted maximum likelihood analysis to develop the linear relationship between Eg or heat production and metabolizable energy (ME) intake, with the effects of a range of dietary and animal factors removed. The net energy (NEm) and ME (MEm) requirements for maintenance derived from the linear relationship between Eg and ME intake were 0.358 and 0.486 MJ/kg BW0.75, respectively, which are 40% to 53% higher than those recommended in energy feeding systems currently used to ration sheep in the USA and the UK. Further analysis of the current dataset revealed that concentrate supplement, sire type or physiological stage had no significant effect on the derived NEm values. However, female lambs had a significantly higher NEm (0.352 v. 0.306 or 0.288 MJ/kg BW0.75) or MEm (0.507 v. 0.441 or 0.415 MJ/kg BW0.75) than those for male or castrated lambs. The present results indicate that using present energy feeding systems in the UK developed over 40 years ago to ration the current sheep flocks could underestimate maintenance energy requirements. There is an urgent need to update these systems to reflect the higher metabolic rates of the current sheep flocks.

Cow-level risk factors for reproductive tract disease diagnosed by 2 methods in pasture-grazed dairy cattle in Ireland

The cow-side diagnosis of reproductive tract disease (RTD) involves identifying the presence of purulent vaginal discharge (PVD) and ultrasonographic endometritis (UE). The objectives of our study were to obtain prevalence estimates for RTD diagnosed by 2 methods (PVD and UE scoring) and to investigate the risk factors for increased probability of RTD if these methods are used in isolation or in combination. Our retrospective observational cohort study tested the hypothesis that RTD assessed by 2 methods would have similar risk factors, and that those would be mainly cow- and calving-related factors. We analyzed data from 5,049 pre-breeding examinations (PBE) from 2,460 spring-calved cows on 8 farms between 2014 and 2018. Cow-related details assessed were days in milk at PBE, breed, lactation number, dry period length, body condition score at calving and PBE, 305-d milk yield, predicted transmitting ability for production and fertility, the presence of a corpus luteum at PBE, and positive diagnosis the previous year. Calving details assessed were type of sire, calf sex, twinning, stillbirth, calving difficulty score, and retained fetal membranes. We conducted statistical analyses using 4 multivariable logistic regression models to identify the risk of RTD diagnosed by (1) PVD in isolation, (2) UE in isolation, (3) the presence of either PVD or UE; and (4) the presence of both PVD and UE. We accounted for herd, cow, and year as random effects in all 4 models. The overall prevalence of RTD in models 1, 2, 3, and 4 were 7.5, 6.7, 11.6, and 2.6%, respectively. Days in milk at PBE, the interaction between days in milk and retained fetal membranes, twinning, and the predicted transmitting ability for calving interval were consistently significant risk factors for positive scores in all 4 models. Considerable calving difficulty [adjusted odds ratio (AOR) = 13.64], Holstein Friesian dam breed (AOR = 2.58), first lactation (AOR = 2.39), and body condition score at PBE (AOR = 1.64) were risk factors for a positive PVD score but not for a positive UE score. Fifth lactation (AOR = 1.69), a beef-sired calf (AOR = 1.46), and the absence of a corpus luteum at PBE (AOR = 1.57) were risk factors for a positive UE score but not for a positive PVD score. These results support the hypothesis that most of the risk factors for PVD and UE are the same but some are distinctly different, implying that in some instances the 2 methods diagnose separate components of the RTD complex.

Feed deprivation in Merino and Terminal sired lambs: (2) the metabolic response under pre-slaughter conditions and impact on meat quality and carcass yield

Under current Australian industry pre-slaughter guidelines, lambs may be off feed for up to 48 h before slaughter. The purpose of this study was to examine what proportion of circulating metabolites at slaughter are due to stress and feed deprivation and if this response differs between Merino and Terminal genotypes. In addition the effect of feed deprivation on carcass weight and meat quality was examined. Jugular blood samples were collected from 88 Merino and Terminal sired lambs at rest and at slaughter following 24, 36 and 48 h of feed deprivation and plasma analysed for glucose, lactate, non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHOB). From the same carcasses hot carcass weight (HCWT) were measured as well as a suite of meat quality traits measured such as M. longissimus lumborum (loin) and M. semitendinosus pH at 24 h postmortem. Loin samples were also analysed for intramuscular fat content and Warner–Bratzer Shear Force. Merino sired lambs had a higher NEFA response compared to Terminal sired lambs at slaughter after 24, 36 and 48 h of feed deprivation, with NEFA levels up to 35% higher than previously reported in the same animals at rest in animal house conditions, whereas BHOB response to feed deprivation was not affected by sire type (P>0.05) and similar to previously reported at rest. In addition to the metabolic effects, increasing feed deprivation from 36 h was associated with a 3% reduction in HCWT and dressing percentage as well as causing increased ultimate pH in the M. semitendinosus in Merino sired lambs. Findings from this study demonstrate that Merino and Terminal sired lambs differ in their metabolic response to feed deprivation under commercial slaughter conditions. In addition, commercial feed deprivation appears to have a negative effect on ultimate pH and carcass weight and warrants further investigation.

Compositional and dimensional factors influencing pork belly firmness

The colour of bloomed m. longissimus was measured 24 h post slaughter for 8165 lamb carcasses produced over 5 years across 8 sites in Australia. Intramuscular fat across a 2 to 8% range and shortloin fat weight were positively associated with meat lightness (L*), redness (a*), yellowness (b*), hue and chroma (P < 0.01). Shortloin muscle weight was negatively associated with these meat colour parameters (P < 0.01), although this was largely accounted for by correlated changes in intramuscular fat (P < 0.01). The effect of sire breeding values for lamb weight, shortloin muscle depth and fat depth on loin L*, a*, b*, hue and chroma were small and varied between lambs of different sire type, dam breed and sex. Thus selection for lean meat yield will have neutral or positive effects on meat colour, while selection for increased intramuscular fat will make the bloomed colour of lamb meat lighter and redder.

Selection for intramuscular fat and lean meat yield will improve the bloomed colour of Australian lamb loin meat

The colour of bloomed m. longissimus was measured 24h post slaughter for 8165 lamb carcasses produced over 5years across 8 sites in Australia. Intramuscular fat across a 2 to 8% range and shortloin fat weight were positively associated with meat lightness (L*), redness (a*), yellowness (b*), hue and chroma (P<0.01). Shortloin muscle weight was negatively associated with these meat colour parameters (P<0.01), although this was largely accounted for by correlated changes in intramuscular fat (P<0.01). The effect of sire breeding values for lamb weight, shortloin muscle depth and fat depth on loin L*, a*, b*, hue and chroma were small and varied between lambs of different sire type, dam breed and sex. Thus selection for lean meat yield will have neutral or positive effects on meat colour, while selection for increased intramuscular fat will make the bloomed colour of lamb meat lighter and redder.

Farmer views on calving difficulty consequences on dairy and beef farms

Calving difficulty (CD) is a key functional trait with significant influence on herd profitability and animal welfare. Breeding plays an important role in managing CD both at farm and industry level. An alternative to the economic value approach to determine the CD penalty is to complement the economic models with the analysis of farmer perceived on-farm impacts of CD. The aim of this study was to explore dairy and beef farmer views and perceptions on the economic and non-economic on-farm consequences of CD, to ultimately inform future genetic selection tools for the beef and dairy industries in Ireland. A standardised quantitative online survey was released to all farmers with e-mail addresses on the Irish Cattle Breeding Federation database. In total, 271 farmers completed the survey (173 beef farmers and 98 dairy farmers). Both dairy and beef farmers considered CD a very important issue with economic and non-economic components. However, CD was seen as more problematic by dairy farmers, who mostly preferred to slightly reduce its incidence, than by beef farmers, who tended to support increases in calf value even though it would imply a slight increase in CD incidence. Farm size was found to be related to dairy farmer views of CD with farmers from larger farms considering CD as more problematic than farmers from smaller farms. CD breeding value was reported to be critical for selecting beef sires to mate with either beef or dairy cows, whereas when selecting dairy sires, CD had lower importance than breeding values for other traits. There was considerable variability in the importance farmers give to CD breeding values that could not be explained by the farm type or the type of sire used, which might be related to the farmer non-economic motives. Farmer perceived economic value associated with incremental increases in CD increases substantially as the CD level considered increases. This non-linear relationship cannot be reflected in a standard linear index weighting. The results of this paper provide key underpinning support to the development of non-linear index weightings for CD in Irish national indexes.

Sire carcass breeding values affect body composition in lambs — 2. Effects on fat and bone weight and their distribution within the carcass as measured by computed tomography

This study assessed the effect of paternal Australian Sheep Breeding Values for post weaning c-site eye muscle depth (PEMD) and fat depth (PFAT), and post weaning weight (PWWT) on the composition of lamb carcasses. Composition was measured using computed tomography scans of 1665 lambs which were progeny of 85 Maternal, 115 Merino and 155 Terminal sires. Reducing sire PFAT decreased carcass fat weight by 4.8% and increased carcass bone by 1.3% per unit of PFAT (range 5.1mm). Increasing sire PEMD reduced carcass fat weight by 3.8% in Maternal and 2% in Terminal sired lambs per unit of PEMD (range 4.3 and 7.8mm), with no impact on bone. Increasing sire PWWT reduced carcass fat weight, but only at some experimental locations. Differences in composition varied between sire types with Maternal sired lambs having the most fat and Merino sired lambs the greatest bone weight. Genetic effects on fatness were greater than the environmental or production factor effects, with the converse true of bone.

Neonatal lamb mortality: factors associated with the death of Australian lambs

The objective of the present study was to examine the factors associated with the death of neonatal lambs. Postmortem autopsy data were collected from 3198 newborn lambs in the Sheep CRCs Information Nucleus Flock situated in various environments throughout southern Australia. The proportion dying by category from highest to lowest was starvation–mismothering (25%), stillbirth (21%), birth injury (18%), dystocia (9%), death in utero–prematurity (10%), predation (7%), cold exposure (5%), undiagnosed (4%), infection (1%) or misadventure (1%). Factors best explaining the probability of lambs falling into a death category included both birth type and birthweight for dystocia, stillbirth, starvation–mismothering and death in utero–prematurity. The probability of a lamb falling into any category was predicted at the mean birthweight, within birth type. Single-born lambs were more likely to die from dystocia and stillbirth, while twin lambs were more likely to die from birth injury, starvation–mismothering or from undiagnosed causes. Triplet lambs were more likely to die from starvation–mismothering or death in utero–prematurity. Sire type (Merino, maternal or terminal) did not affect the proportions of lambs within any category. The proportions lost to each cause of death were largely consistent among locations, despite the rate of death varying. Dystocia, stillbirth and birth injury, as evidenced by the presence of oedema around the head and neck or by lesions of the central nervous system, accounted for 48% of autopsied lambs. We conclude that for improvements to occur in the rates of lamb survival, the Australian sheep industry must focus on minimising losses due to dystocia, stillbirth, birth injury and starvation.

The Sex Specific Genetic Variation of Energetics in Bank Voles, Consequences of Introgression?

Interaction between mitochondrial and nuclear genomes is expected to affect energetic phenotypes of traits linked to mitochondrial physiology, further influencing the fitness. A rodent, the bank vole (Myodes glareolus), has a population structure completely or partially introgressed with mitochondria from its relative, the red vole (M. rutilus). Females that carried either bank vole mitochondria or mitochondria from the introgressed species were repeatedly mated with males of both mtDNA types. We found that in males, but not in females, morpho-physiological phenotypes are affected by sire type, causing decreases in body mass (BM) and basal metabolic rate (BMR; including BM corrected, rBMR) in individuals sired by fathers carrying introgressed mitochondria. Higher effect sizes for the proportion of additive genetic variation (and 5.6, 1.9 and 3.6 times higher narrow sense heritability for BM, BMR and rBMR, respectively), and lower for proportion of environmental variation were detected in progeny of non-introgressed males. Our data indicate that co-adapted and possibly co-introgressed nuclear genes related to energetic physiology have an important role in adaptation to the northern conditions in bank voles, and that sex linked nuclear genes are a potential source for variation in basal metabolic rate.