Eye Muscle Depth Research Articles

78 Estimates of genetic parameters for weight, wool, and carcass traits of Rambouillet sheep

Abstract The Rambouillet sheep breed is the foundation to most western range sheep in the U.S. Through the National Sheep Improvement Program (NSIP), Rambouillet breeders seek to improve economically relevant traits. However, the parameters used in the NSIP genetic evaluation were last estimated two decades ago. Our aim was to re-estimate genetic parameters for body weight (BW), carcass, and wool traits. Data were provided by NSIP, which included BW at birth (BWT; n = 28,817), weaning [WWT; n = 5,633; age: 68 (SD 16) day], early post-weaning [PWTE; n = 23,303; 128 (SD 22) d], late post-weaning [PWTL; n = 7,689; 201 (SD 45) d] and as yearlings [YWT; n = 5,830; 375 (SD 33) d]. Yearling ultrasound scans of 12th rib backfat depth (YCF; n = 2,447) and eye muscle depth (YEMD; n = 2,457) were also available. Yearling wool traits were fiber curvature (YFC; n = 6,009), fiber diameter (YFD; n = 9,880), fiber diameter coefficient of variation (YFDCV; n = 8,803), greasy fleece weight (YGFW; n = 11,859) and staple length (YSL; n = 11,270). The pedigree consisted of 36,297 individuals. Animals with phenotypic records were progeny of 333 sires and 1,727 dams. A succession of univariate animal models was fitted. The most comprehensive model included direct and maternal additive genetic effects, their genetic covariance, and maternal permanent environmental and residual effects. Phenotypes were pre-adjusted for birth-rearing type category and, as covariates, dam age and age at recording. Contemporary group—a concatenation of flock, year, season, management group, sex, and, excluding BWT, recording date—was the only fixed effect fitted in the model. Model selection was based on the log-likelihood ratio test, and Akaike and Bayesian information criteria. The data structure, namely dams and their daughters and granddaughters contributing data, allowed reliable testing of the maternal effect terms. The direct-maternal genetic covariance did not explain variation for any trait (P > 0.18). The most parsimonious model for BW traits included direct and maternal additive genetic, and maternal permanent environmental, effects. For carcass and wool traits, only direct additive genetic effects were included in the final model. Such was unsurprising, as maternal effects often diminish as animals age. For the final models fitted (Table 1), direct heritabilities (± SE) for body weights ranged from 0.14 ± 0.01 (BWT) to 0.38 ± 0.04 (PWTL); the maternal heritabilities ranged from 0.04 ± 0.02 (PWTL; YWT) to 0.13 ± 0.01 (BWT). For carcass traits, direct heritabilities were 0.13 ± 0.04 (YCF) and 0.31 ± 0.05 (YEMD). For wool traits, they ranged from 0.37 ± 0.02 (YSL) to 0.58 ± 0.02 (YFD). These re-estimated parameter values are consistent with those used by NSIP, with the exception of PWTL (greater) and YSL (lower). With genomic data accumulating in Rambouillet, further refinements in parameter estimation are planned.

Selecting an appropriate statistical model for estimating genetic parameters: A case study of pig maternal breeds in Czechia

A three-trait statistical model was designed for backfat thickness (BFT) and loin eye muscle depth (LMD) with accompanying variable average daily gain (ADG). Data from 82,507 Czech Large White and 37,556 Czech Landrace pigs were collected during on-farm performance testing from 2013 to 2022. Several animal models were tested with different combinations of effects and complexity. Model performance was evaluated by the linear regression (LR) method and predictivity. In Czech Large White, the preferred model comprised fixed effects of sex, birth year, herd, and ultrasound device, as well as random effects of herd-year-season (HYS), litter, and animal. In Czech Landrace, HYS was treated as fixed instead. The inclusion of maternal effects was not supported due to questionable impact on the main statistics. The selected model yielded mean absolute bias of 0.11 and 0.19, mean determination of 0.39 and 0.21, mean population accuracy of 0.36 and 0.31, and mean predictivity of 0.13 and 0.08 in Large White and Landrace, respectively. Heritability estimates were overall lower than those reported by other authors: 0.23, 0.10, and 0.10 in Large White and 0.26, 0.10, and 0.09 in Landrace for ADG, BFT, and LMD, respectively. Genetic correlations, on the other hand, reached relatively high values: 0.61, 0.61, and 0.66 in Large White and 0.71, 0.92, and 0.70 in Landrace for ADG-BFT, ADG-LMD, and BFT-LMD, respectively.

Bioeconomic selection indexes for terminal lamb systems in tropical conditions

The main challenge for sheep farming in Brazil is the regularity in the quantity and quality of animals destined for slaughter. The selection for several traits simultaneously, considering their economic relevance, can improve the production efficiency in the finishing systems, the quality of meat offered to the consumer market, and, consequently, the profitability. The objective was to develop selection indexes for three terminal lamb scenarios: extensive system (EXS), semi-intensive system (SIS), and intensive system (INS). The costs and revenues calculated were according to the national average prices in 2021. The economic values were determined by the partial derivatives of the profit function, changing one trait at a time, by 1 unit, while keeping the other traits constant. For the traits of the selection objective: feed conversion ratio, weight at 180 days, and dressing percentage, the economic values (US$) were, respectively, EXS: − 1.91, 1.13, 1.53; SIS: − 3.16, 1.35, 1.54; INS: − 6.30, 0.99, 1.55. Feed conversion ratio was the trait that presented the highest economic value for all systems, affecting production costs and production efficiency. Additive genetic variance and genetic correlation values obtained were in literature. The traits of selection criteria were: weight at 180 days, measured in kg, eye muscle depth, and subcutaneous fat depth, measured by the ultrasound. The selection index weight for the traits of the criterion of selection were, respectively, EXS: 7.850, 4.421, 1.079; SIS: 9.788, 3.988, − 0.711; INS: 10.087, 2.803, − 5.272. The prediction of economic gain per animal was US$6.21 (EXS), US$7.35 (SIS), and US$7.16 (INS). In addition, the accuracy of the indexes was 0.88 (EXS), 0.91 (SIS), 0.91 (INS). The selection for growth and carcass traits as selection criteria can improve the performance and dressing percentage of the animal. The accuracy of the index showed to be favorable to replicate these indexes in similar scenarios of terminal lamb, which can improve the genetic progress and profit of the herd.

Prediction of lamb carcase C-site fat depth and GR tissue depth using a non-invasive portable microwave system versus body condition scoring

This study compared portable ultra-wide band microwave system (MiS) versus body condition score to predict C-site fat depth, GR tissue depth and eye muscle depth (EMD) in lambs. Experiment 1 assessed MiS and condition score to predict ultrasound measured C-site and EMD (n = 1549). Precision and accuracy was greatest for the MiS measurement with liveweight included in the model, with a C-site predicted RMSEP of 0.58 mm, R2 0.60 and bias of 0.021 mm and an EMD predicted RMSEP of 2.27 mm, R2 0.72 and bias of 0.088 mm. Experiment 2 (n = 900) assessed pre-slaughter MiS scanning and condition scoring to predict carcase GR tissue depth, C-site fat depth and EMD. MiS performed better than condition score for all three carcase trait predictions, regardless of the inclusion of liveweight, with the highest precision and accuracy for GR tissue depth determination with a RMSEP of 3.68 mm, R2 0.63 and bias 0.072 mm.

Development of a routine genetic evaluation and a total merit index for sheep breeds with focus on meat production

• A routine genetic evaluation was developed for sheep with focus on meat production. • Breeding values for individual traits, a Meat and a Fitness index as well as a Total merit index are calculated weekly. • Traits are weighted in a way so that the theoretical selection response is positive for all traits. The introduction of a routine genetic evaluation for specialized meat sheep (Blackheaded meat, Suffolk, Texel, Ile de France, Dorper, and Berrichon du Cher) and land sheep with focus on meat production (Merinoland) is described. Even though performance recording has existed for several production and fitness related traits and years, breeding values have not been officially available for sheep in Austria until 2017. Meat performance traits, recorded for purebred animals of both sexes, include average daily gain, fat depth and eye muscle depth. Historic computer tomography performance recording results serve as auxiliary traits. Regarding functional traits, lambing interval, number of lambs born and number of lambs born alive are considered. The routine genetic evaluation is carried out twice a year, at the beginning of January and at the end of June. Additionally, breeding values and reliabilities are calculated at weekly intervals but only uploaded if the change in reliability exceeds 5%-points or a new individual performance recording result is available. All estimated breeding values are standardised to relative breeding values with a mean of 100 (rolling base including rams aged 5–15 years), and a genetic standard deviation of 12, higher values are favourable. Apart from breeding values for individual traits, subindices for meat and fitness traits as well as a Total merit index (TMI) are calculated. For the calculation of the Meat index, the relative weights (in %) for average daily gain (direct) : muscle depth : fat depth are 36 : 62 : 2 for Merinoland and 44 : 52 : 4 for meat sheep. For fat depth, the breeding values are transformed to an intermediate optimum in the index calculation. In the Fitness index, the relative weights (in %) for lambing interval : lambs born maternal : lambs born paternal: lambs born alive maternal : lambs born alive paternal are 35.0 : 33.3 : 8.3 : 18.3 : 5.0 (Merinoland) and 20.0 : 49.0 : 17.0 : 10.0 : 4.0 (Meat sheep). Including the trait average daily gain maternal in the meat complex, the relative weights (in %) of Meat : Fitness are 40 : 60 and 60 : 40 in Merinoland and Meat sheep, respectively. The TMI was defined in a way so that the calculated selection response is positive for all single traits in order to avoid an unfavourable development. Thus, it serves as a starting point for a breeding objective that is both, economically feasible and sustainable in the long-term. Further traits that may be considered in a future TMI are e.g. longevity and selected conformation traits.

The impact of lamb diets containing either barley or corn on growth performance and carcass quality

Background and Aim:Grains, such as barley (BAR) and corn (CORN), are major energy sources for small ruminants. This study aimed to assess the impact of feeding either BAR or CORN-based diets on growth performance and carcass characteristics.Materials and Methods:Awassi male lambs, average body weight of 20.4±0.49 kg, were chosen randomly. Lambs were acclimated for 10 days and assigned to one of two diets (1) BAR and (2) CORN. Feeding continued for 70 days with 60 days of data collection. Daily intake was recorded. Measurements of body weight were taken starting from day 1 then once per week throughout the study period. On day 40, six lambs were randomly chosen from each group and placed in metabolism cages to assess digestibility and N balance. Lambs were slaughtered on the last day of the study to evaluate carcass characteristics and meat quality.Results:Neutral and acid detergent fiber and ether extract intake were greater (p≤0.05) for lambs fed the BAR diets. Nitrogen loss in feces tended to be greater (p=0.09) for the CORN diet. Eye muscle depth (mm) tended to be greater (p=0.07) for the BAR diet. Nutrient digestibility, daily weight gain, carcass characteristics, and meat quality were not different (p≥0.1) between diets.Conclusion:The results herein demonstrate that feeding BAR grain improved nutrient intake efficiency and consistency and did not affect weight gain and carcass traits. BAR-based diets might be a useful alternative to CORN for feeding growing lambs.

Genetic analyses of novel traits derived from CT scanning for implementation in terminal sire sheep breeding programmes

This study used archived CT scanning images from Texel (n = 3534), Suffolk (n = 2357) and Charollais (n = 2013) ram lambs, scanned between 1997 and 2016 as part of the national UK terminal sire breeding programmes, to measure new, previously unexploited, CT phenotypes for product quality. The new CT phenotypes included 12 traits relating to eye muscle dimensions, spine region lengths and vertebrae numbers, and intramuscular fat (IMF), as a predictor of meat quality. The aim was to estimate genetic parameters for these new traits, confirm genetic parameters for existing growth and carcass traits, and investigate relationships amongst traits, when adjusted for either age or live weight. The new CT traits were generally moderately heritable (h2 ranging from 0.23-0.54 when adjusted for age) within each breed. Notable exceptions were: vertebrae counts, which had lower heritabilities (0.11-0.18) in the Suffolk and Texel; lumbar region spine length and vertebrae count in the Charollais, (0.04); and CT-predicted IMF in the Charollais (0.88). Generally, genetic variation decreased, but heritabilities increased, when traits were adjusted for live-weight rather than age, ranging from h2 0.21-0.74 for the new CT traits, except for the Charollias lumbar spine length (0.01) and CT-predicted IMF (0.87). Within-breed genetic correlations between new CT traits and current CT traits (carcass fat and muscle weights, muscularity), ultrasound tissue depths, or scan weight (at ~21 weeks), were low to moderate. High genetic correlations were observed between ultrasound and CT measured eye muscle depth (r = 0.77-0.85). Genetic correlations between CT-predicted IMF and total carcass fat estimates, however, were unfavourable (large and positive; r = 0.66-0.96), especially in the Suffolk and Charollais, suggesting little scope for divergent selection between fat depots. Some unfavourable genetic correlations of spine length with CT muscle weight or eye muscle depth were also estimated, after live weight adjustment. Possibilities therefore exist for genetic selection on additional product quality traits that can be routinely measured by CT scanning. Adjusting new and existing carcass traits for live weight, rather than age, should increase heritabilities and provide a more relevant industry end-point. These findings could contribute to the production of a new selection index, with optimal weightings on growth, carcass and product quality traits, for a sustainable UK terminal sire sheep breeding programme.

Consumer Perceptions of Meat Redness Were Strongly Influenced by Storage and Display Times

Lamb (n = 79) meat colour was scored by 879 untrained consumers using a scale of 0 (brown) to 100 (red). This consumer colour score (CCS) was obtained on m. longissimus lumborum (loin) and m. semimembranosus (topside), stored for short (5–7 days), medium (33–35 days), and long periods (110–112 days) and a retail display time of up to 4 days. Consumers perceived topside to be less red initially and changed from red to brown more rapidly when stored for the long-storage period (p < 0.01). Whereas, the initial CCS of loin samples were similar across the storage periods (p > 0.05). CCS and the instrument measure oxy/met (reflectance of light at wavelengths 630 nm and 580 nm) had a low correlation coefficient of 0.33 (p < 0.01). The propensity for lamb growth and leanness indicated by sire breeding values for lamb weight, eye muscle depth, eye muscle fat depth, and loin intramuscular fat had varied and inconsistent effects on CCS. Therefore, even the selection on CCS.

The effect of a fodder beet versus rye-grass grazing regime during mid-to-late gestation twin-bearing ewes on dam and progeny performance and lamb survival

ABSTRACT The objective was to determine the effect of grazing fodder beet versus ryegrass-dominant pasture from mid-to-late gestation on dam and offspring performance under practical farming conditions. Twin-bearing ewes were randomly allocated to grazing regimes of either fodder beet plus ad libitum ryegrass/clover hay (FB; n = 100) or ryegrass-dominant pasture plus ad libitum ryegrass/clover hay (RG; n = 100) with three replicates per group, from pregnancy day (P) 100–110 to birth. At P135, 10 ewes per treatment were randomly selected from each replicate, slaughtered and back fat and eye muscle depth and fetal body weight and composition were measured. Samples were evaluated for selected blood metabolites. Ewe BW and BCS change and lamb growth were measured, and lamb survival from birth to weaning calculated. Compared with RG, FB ewes had lower ADG and overall lower BCS resulting from increased mobilisation of both fat and muscle. Lambs born to FB-ewes had lower BW and postnatal growth rates and increased mortality from birth to weaning (29% versus 12%). Body composition and blood parameters indicated that FB compared to RG ewes were subject to undernutrition. This study provides new insights into the consequences of FB grazing regimes, as an alternative to ryegrass pasture, on animal performance.

The inclusion of black cumin meal improves the carcass characteristics of growing Awassi lambs.

Background and Aim:Black cumin meal (BCM) is the principal by-product that can be obtained from black cumin seed (Nigella sativa L) after the oil is removed from the fruit and represents 70-75% of the fruit weight. The aim of this experiment was to assess the influence of feeding BCM on the carcass characteristics and meat quality of growing lambs.Materials and Methods:Twenty-four Awassi lambs were randomly divided into two dietary treatments. The lambs were penned individually in single pens and provided access to ad libitum feed and water. The dietary treatments were no BCM (control [CON]; n=12) or 150 g BCM/kg (BCM 150; n=12) of dietary dry matter.Results:Lambs fed BCM had greater (p≤0.01) fasting live BW, and hot and cold carcass weights. Leg fat and eye muscle depth were lower (p≤0.05) in CON versus BCM lambs. Meat whiteness (L*), redness (a*), and yellowness did not differ between lambs fed the two diets.Conclusion:The inclusion of BCM improves lamb carcass characteristics, but does not affect lamb meat quality.

Growth, body composition and body wrinkle are favourably correlated with reproductive performance in 2-8-year-old Merino sheep

Context Despite the increased economic importance of reproductive rate in Australian Merinos, there have been low genetic improvements in reproductive performance over the past several decades. Genetically improving reproductive traits through direct selection is restricted by low heritability, low selection intensity directly on reproductive traits, high recording costs and lack of accurate maternal pedigrees in the majority of industry breeding programs. However, indirect selection via correlated traits may be useful as a supplement to direct selection or even on its own where reproduction records are not collected. Aims The aims of the present study were to determine whether various production and quality traits have the potential to be used as indirect selection criteria for genetically improving lifetime reproductive rate, but also whether their selection could be detrimental to reproduction via unfavourable correlations. Methods Reproductive traits studied included pregnancy rate (ewes scanned pregnant per ewe joined), fetal number (number of fetuses scanned per ewe joined), number of lambs born (per ewe joined), number of lambs weaned (per ewe joined) and ewe rearing ability (number of lambs weaned per fetuses scanned). Using data from the SA Selection Demonstration Flocks project (1997–2005), reproductive traits were modelled against various visual and production traits to estimate correlations. Key results Favourable genetic correlations with reproductive traits were estimated with adult ewe bodyweight (0.37–0.50), hogget eye muscle depth (HEMD, 0.40–0.57), fat depth (HFAT, 0.27–0.48) and hogget body (HBWS) and neck wrinkle scores (–0.13 to –0.50). However, the estimates for genetic correlations with hogget eye muscle depth and fat depth were lower when bodyweight was fitted as a covariate, being 0.11–0.35 and 0.17–0.32 respectively. Genetic correlations with ewe rearing ability were generally unfavourable (except those with hogget body and neck wrinkle scores, which were –0.24 and –0.15 respectively), but were either negligible (adult ewe bodyweight, hogget eye muscle depth, fibre diameter and fleece weight) or low in magnitude(fat depth). Unfavourable genetic correlations were observed between fibre diameter and reproductive traits (0.13–0.33). Fleece weight had negligible genetic correlations with all reproductive traits studied (–0.08 to 0.10). Predictions of response to index selection using indirect criteria of one or more of yearling weight, HBWS, HEMD and HFAT measurements projected substantial genetic gains in the number of lambs weaned per ewe joined (NLW). Without reproduction records on the dams of candidates for selection, indirect selection using all four indirect criteria (yearling weight, HBWS, HEMD and HFAT) was predicted to achieve 112–168% of the genetic gains of direct selection for NLW. When all indirect and direct criteria for NLW are combined as part of index selection, even larger gains for NLW are predicted (from 164–215% of direct NLW genetic gains). Conclusions Findings from the present study suggest that bodyweight, HEMD and HFAT and HBWS could be potentially beneficial as indirect selection criteria for lifetime reproductive rate. Selection for reduced fibre diameter is potentially detrimental to reproductive performance; however, selection for improved fleece weight is unlikely to have any effect on genetic gain for reproductive traits. Implications Use of indirect selection for lifetime reproductive could allow for genetic gain when either used with or without the direct selection criteria of reproduction records.

236 Comparison of ultrasound scanned loin eye muscle characteristics and back-fat depth measured in lean muscle selection and control Katahdin sheep flock

Abstract Sheep farming is an important enterprise for many farmers in US, and meat is a viable protein resource for human nutrition. However, increasing concern for health aspects of meat consumption has led consumers to demand a higher ratio of lean to fat tissues. Application of ultrasound carcass scanning in meat animal selection and marketing as a performance prediction will enhance the selection efficiency, accuracy and profitability. One hundred and sixty two mixed-age Katahdin ewes were evenly divided into a high lean muscle selection (n = 81) and control (n = 81) flock based on the prescreened ultrasound measures, including loin eye muscle area (LEA), loin eye muscle width (LEW), and depth (LED), and back-fat depth (BFD). The LEA is measured between the 12th and 13th ribs lateral and perpendicular to the vertical column and parallel to rib covering the longissimus dorsi muscle. Live animal measurements were conducted using ultrasound scanner fitted with a 3.5 MHz linear transducer (ExaGo, France) prior to fall breeding schedules. Live weight (LWT), body condition score (BCS) and FAMACHA score (FAM) were recorded. Data were analyzed using GLM procedures of SAS statistics. There was no difference between selection and control flocks for LWT, BCS and FAM; however, LEA, LEW, LED and BFD were significantly (P &amp;lt; 0.05) greater for the lean selection over control flock (Table 1). The correlation coefficients (P &amp;lt; 0.01) were found as moderate (r = 0.6) to high (r = 0.8) among LED, LEA, LEW and BFD, whereas these traits showed lower (r = 0.4) but significant (P &amp;lt; 0.01) correlations with LWT. The results indicate that lean muscle selection in sheep with ultrasound scanning of longissimus muscle characteristics will enhance the production efficiency and genetic gain and facilitate producing a high value meat product.

96 Cover Crop Grazing and Backgrounding on Carcass Quality

Abstract Integration of sheep into cropping systems via cover crop grazing leases has potential to benefit sheep producers with a source of inexpensive, high quality forage. We examined this potential by comparing lamb growth and carcass traits of four rearing systems: grain-finished control (GR), cover crop brassica-finished (CCB), cover crop mixture-finished (CCM), and background on brassica and finished on grain (BK-GR). Dorset x Polypay lambs (n = 60; 3 pens or pastures, 5 lambs each) were blocked by body weight and randomly assigned to treatment. All diets were provided to maximize voluntary dry matter intake. Lambs were harvested after 6 wks of feeding for GR and 8 wks for CCB, CCM and BK-GR (BK-GR = 4 wks brassica then 4 wks grain). Grain-fed lambs (GR and BK-GR, 442 g/d) grew faster than pasture-fed lambs (CCB and CCM, 152 g/d) prior to harvest (Table 1, P &amp;lt; 0.01) and attained greater body mass (HCW), muscling (LEA, EMD), fatness (BF, BWF) and yield grade (all P &amp;lt; 0.05). Growth of pasture-fed lambs declined 38% over time (247 wk 1–4 vs. 152 g/d wk5-8; P &amp;lt; 0.05). Pasture-fed lambs were leaner than grain-fed lambs (BF, yield grade; P &amp;lt; 0.01), yet attained a yield grade 2 average. Background lambs (BK-GR) exhibited a 107% increase in growth when fed grain (232 g/d pasture vs. 481 g/d grain, P &amp;lt; 0.01) and were fatter (BF, P &amp;lt; 0.05) yet had reduced eye muscle depth (P &amp;lt; 0.01) at harvest than GR lambs. Lambs did not differ in growth or any carcass measurement according to pasture type (CCB vs. CCM). We conclude that 8 wks of cover crop finishing produced acceptable carcass weight and finish. Backgrounding on cover crops followed by 4 wks of grain finishing results in marked compensatory gain with lambs achieving the same carcass size and similar qualities to lambs fed only grain.

Prediction of dressing percentage, carcass characteristics and meat yield of goats, and implications for live assessment and carcass-grading systems

Abstract Context Dressing percentage (DP) and meat yield (MY) predictions using live assessments and carcass measurements enable objective valuation of animals and their carcasses. We hypothesised that distribution of goat carcass tissues affects predictive value of live body condition scoring (CS) methods and carcass measurements for these traits. Aims The present paper aimed to assess the value of CS methods for prediction of DP and MY and of carcass measurements for prediction of MY. Methods Correlation and regression analyses from a dataset (n = 1014 goats) highly heterogeneous for factors influencing DP and MY were used to assess (1) the value of live-goat assessments and classifications, including five CS methods, age (dentition), liveweight (LW), sex, fleece characteristics and breed or genotype to predict DP and MY, and (2) the value of hot standard carcass weight (HSCW) and carcass GR (soft tissue over the 12th rib) tissue depth, eye-muscle depth and eye-muscle area to predict MY. Key results Among kids, LW accounted for 1% (residual standard deviation of 2.6%) of variation in DP, 22% (2.3%) in MY (% LW) and 34% (2.5%) in MY (% HSCW). LW plus the best CS method accounted for 24% (2.3%) of variation in DP, 58% (1.7%) in MY (% LW) and 61% (2.0%) in MY (% HSCW). Among all goats, LW plus CS accounted for up to 21% (3.2%), 39% (2.1%) and 45% (2.2%) of variation in these traits. Regression models that included age, sex, fleece type, breed or genotype, LW and CS accounted for 67% (2.5%), 72% (1.9%) and 72% (2.1%) of variation in DP, MY (% LW) and MY (% HSCW). Among carcass measurements, HSCW plus eye-muscle depth had best predictive value, accounting for 61% (2.3%) of variation in MY (% HSCW) for kids and 40% (2.9%) for all goats. Conclusions The body condition-score methods that best relate to DP and MY (% LW or % HSCW) assessed the shape of M. longissimus lumborum (eye muscle) in the lumbar region, which relates to muscularity of goats, rather than subcutaneous fat depth such as assessed at the GR-site. Implications The results guide potential targets for future developments in live-goat assessment, carcass classification and grading, and trading languages underpinned by value-based marketing.

Farklı Besi Zamanlarındaki Ultrasonik Ölçümler ile Karkas Özellikleri Arasındaki İlişkilerin Belirlenmesi

Bu çalışma, Akkaraman kuzularının farklı entansif besi sürelerinde ultrasonik ölçümler ile karkas özellikleri arasındaki ilişkileri çok değişkenli bir korelasyonla (kanonik) tahmin etmek amacıyla yapılmıştır. Bu amaçla yaklaşık 2.5 aylık yaşta ortalama 20 kg canlı ağırlıkta 16 adet erkek Akkaraman kuzuları besiye alınmış, 10 günlük alıştırma periyodu ve 70 günlük entansif besi sonunda kesime gönderilmiştir. Hayvanlara besi süresince 150 g kuru yonca otu ve ad-libitum olarak kesif yem verilmiştir. Besi başı, ortası ve sonundaki ultrasonik ölçümler olarak göz kası derinliği, göz kası üstü yağ kalınlığı ile deri kalınlığı bağımsız değişken veri seti olarak alınırken, karkas özellikleri ise bağımlı değişken veri seti olarak alınmıştır. Sonuç olarak Akkaraman kuzularının besi başında kanonik korelasyon katsayıları 0.999, 0.977 ve 0.549 iken; besi ortasında 0.980, 0.931 ve 0.770, besi sonunda ise 0.999, 0.996 ve 0.814 olarak belirlenmiştir. Besi başında ilk kanonik korelasyon katsayıları ve besi sonunda birinci ve ikinci kanonik korelasyon katsayıları istatistik olarak önemli iken (P&amp;lt;0.05), besi ortasındaki kanonik korelasyon katsayıları istatistik olarak önemli olmadıkları saptanmıştır. Sonuç olarak, Akkaraman kuzularının besi süresince alınan ultrasonik ölçümlerinin karkas özelliklerinin tahmininde kullanılabileceği tespit edilmiştir.

Effect of feeding forage or concentrate starter diets in early life on life-time growth, carcass traits and meat quality of Wagyu × Friesian cattle

Context Nutrition in early life can affect the long-term performance of livestock. Aims The present study evaluated the effects of rearing Wagyu × Holstein Friesian heifer calves either on a concentrate pelleted starter (CS; 90% DM, 19.3% crude protein (CP), and 13.8 MJ metabolisable energy (ME) per kilogram DM) or a forage starter (FS, ensiled alfalfa, Medicago sativa; 45% DM, 18.5% CP and 9.7 MJ metabolisable energy per kilogram DM) on lifetime growth, blood metabolites, carcass traits and meat quality. Methods Calves (n = 60) were allocated either to CS or FS diets. All calves received their solid feeds ad libitum from Week 1 and were fed milk in group pens (n = 10/pen) at 4 L/calf.day until Week 7, then 2 L/calf.day for 2 weeks. Calves were transferred to pasture 1 week after milk removal, with starter feeds removed by Week 15. All heifers were then managed as one group on a pasture-based diet until slaughter at 26–30 months of age (average of 483 kg liveweight). Key results Calves offered the CS diet were 14 kg heavier than were calves on the FS diet at 15 weeks (P &amp;lt; 0.001). However, liveweight was similar between the groups by the time of slaughter (P &amp;gt; 0.1). All blood parameters studied were similar (P &amp;gt; 0.05) between the treatments at 12 months and at slaughter. Depth of eye muscle and subcutaneous fat, measured using ultrasonography before slaughter, carcass weight and meat pH, marbling, shear force, moisture loss during cooking, total fat and fat and meat colour were also similar between the treatments (P &amp;gt; 0.05). Some potential was found for using blood markers to predict carcass traits and meat quality. Conclusions Solid feed type during rearing had little effect on liveweight or meat characteristics from 12 months of age to slaughter of Wagyu × Friesian heifers. Implications Calves can be reared on FS diets with similar long-term production performance as on CS diets.

Performance of sheep systems grazing perennial pastures. 2. Wool quality and lamb growth

This study evaluated wool quality and lamb production from four management systems with Merino ewes grazing a perennial pasture between 2006 and 2010, using different combinations of lambing time, ram breed and percentage of summer-active pasture species. All systems were stocked at a similar midwinter rate (dry-sheep equivalents per hectare of 8, 10.2, 13, 11.2 and 11.2 in the successive seasons 2006–2010). Liveweight, condition score, C fat and eye muscle depth at weaning of both Merino and crossbred lambs were always higher (P &amp;lt; 0.05) for lambs born in July than those born in September. Similarly, the sale weight of lambs born in July was always higher (P &amp;lt; 0.05) than of lambs born in September, partly because these lambs were usually retained for longer before sale. When lambs were born in September, sheep systems that carried higher numbers of ewes per hectare at the same midwinter stocking rate produced sale weights of lambs similar to those with fewer ewes, except where systems with fewer lambs per hectare enabled lambs to be retained for longer in favourable seasons. A higher percentage of lucerne (Medicago sativa, 40% cf. 20%) increased lamb sale weights only in favourable seasons. Clean fleece weights per ewe and staple strength were similar among systems in most years (2008–2010), although mean fibre diameter was lower (P &amp;lt; 0.05) in both late lambing systems (with 40% and 20% lucerne). The results indicate that choice of lambing time, ram breed and the flexibility to alter lamb sale date with seasonal conditions will have a larger impact on the performance of individuals than number of ewes per hectare where systems are grazed at the same midwinter stocking rate.

Pre‐pubertal growth, muscle and fat accumulation in male and female sheep—Relationships with metabolic hormone concentrations, timing of puberty and reproductive outcomes

Metabolic homeostasis is aligned with changes in growth and body composition, through processes mediated by circulating metabolites and metabolic hormones, and is eventually linked to reproductive success. In the present study with sheep, we determined the relationships among phenotypic and genotypic rates of growth, muscle and fat accumulation, and the circulating concentrations of metabolic and tested for relationships with the timing of puberty and subsequent reproductive outcomes. We used 64 females and 62 males with known phenotypic values for depth of eye muscle (EMD) and fat (FAT) and known Australian Sheep Breeding Values at post-weaning age for live weight (PWT), depth of eye muscle (PEMD) and depth of fat (PFAT). Blood plasma sampled every 20min for 8hr via was assayed for growth hormone (GH), insulin-like growth factor I (IGF-I), insulin, leptin, ghrelin, follistatin, glucose and non-esterified fatty acids (NEFA). In males, PWT was positively related to the concentrations of GH, follistatin and glucose, whereas FAT and PFAT were positively related to IGF-I concentrations (p<.01). Testosterone concentration was negatively related to muscle variables (p<.001) and to PFAT (p<.05). In females, the only significant relationship detected was the positive link between EMD and insulin concentrations (p<.05). Reproductive variables were only measured in females. Live weight at first oestrus was related positively to insulin concentration and negatively to GH concentration (p<.05). No other relationships with reproductive variables were significant. The relationships that were detected suggest subtle differences between the sexes in the way their metabolic homeostasis responds to changes in the rates of growth, and muscle and fat accumulation, perhaps due to interference by testosterone in the males.

Feed deprivation in Merino and Terminal sired lambs: (1) the metabolic response under resting conditions

The aim of this study was to examine the metabolic response to feed deprivation up to 48 h in low and high yielding lamb genotypes. It was hypothesised that Terminal sired lambs would have decreased plasma glucose and increased plasma non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHOB) concentrations in response to feed deprivation compared to Merino sired lambs. In addition, it was hypothesised that the metabolic changes due to feed deprivation would also be greater in progeny of sires with breeding values for greater growth, muscling and leanness. Eighty nine lambs (45 ewes, 44 wethers) from Merino dams with Merino or Terminal sires with a range in Australian Sheep Breeding Values (ASBVs) for post-weaning weight (PWT), post-weaning eye muscle depth and post-weaning fat depth (PFAT) were used in this experiment. Blood samples were collected via jugular cannulas every 6 h from time 0 to 48 h of feed deprivation for the determination of plasma glucose, NEFA, BHOB and lactate concentration. From 12 to 48 h of feed deprivation plasma glucose concentration decreased (P < 0.05) by 25% from 4.04 ± 0.032 mmol/l to 3.04 ± 0.032 mmol/l. From 6 h NEFA concentration increased (P < 0.05) from 0.15 ± 0.021 mmol/l by almost 10-fold to 1.34 ± 0.021 mmol/l at 48 h of feed deprivation. Feed deprivation also influenced BHOB concentrations and from 12 to 48 h it increased (P < 0.05) from 0.15 ± 0.010 mmol/l to 0.52 ± 0.010 mmol/l. Merino sired lambs had a 8% greater reduction in glucose and 29% and 10% higher NEFA and BHOB response, respectively, compared to Terminal sired lambs (P < 0.05). In Merino sired lambs, increasing PWT was also associated with an increase in glucose and decline in NEFA and BHOB concentration (P < 0.05). In Terminal sired lambs, increasing PFAT was associated with an increase in glucose and decline in NEFA concentration (P < 0.05). Contrary to the hypothesis, Merino sired lambs showed the greatest metabolic response to fasting especially in regards to fat metabolism.

A genetic evaluation of growth, ultrasound, and carcass traits at alternative slaughter endpoints in crossbred heavy lambs.

Genetic parameters were estimated for growth, ultrasound, and carcass traits in a Canadian crossbred heavy lamb population. Traits analyzed included birth, weaning, post-weaning, and ultrasound scanning weights; pre- and post-weaning average daily gain; ultrasonically measured eye muscle and fat depths; hot carcass weight; fat depth at the GR site (110 mm from the midline on the 12th rib); carcass conformation scores; saleable meat yield; price grid value; and total carcass value. The impact of three alternative slaughter endpoints (slaughter age, carcass weight, and carcass fatness) on genetic parameter estimates was also evaluated. In general, carcass traits were found to be moderately heritable, with heritability estimates ranging from 0.17 ± 0.02 for hot carcass weight at a constant slaughter age to 0.34 ± 0.02 for average carcass conformation score at a constant carcass weight. Heritability estimates were similar when observations were adjusted to alternative slaughter endpoints, but for some traits, phenotypic variance and genetic correlation estimates differed. Genetic correlations between carcass traits and growth and ultrasound traits were typically favorable. Ultrasonically measured eye muscle depth and fat depth were found to be moderately to strongly positively correlated with hot carcass weight (0.33 ± 0.15 to 0.71 ± 0.19) and fat depth at the GR site (0.38 ± 0.14 to 0.74 ± 0.12), respectively, reaffirming the usefulness of selection on ultrasound traits to improve carcass yield and quality. Genetic correlations among carcass traits were generally favorable, with the exception of moderate unfavorable positive genetic correlations between fat depth at the GR site and primal cut carcass conformation scores (0.31 ± 0.05 to 0.60 ± 0.05). Overall, the results of this research suggest that there is potential to improve carcass yield and quality through genetic selection and provides the population-specific genetic parameter estimates needed for the genetic evaluation of carcass traits in the Canadian sheep population. Nevertheless, the optimal endpoint for carcass trait genetic evaluations will need to be further investigated, considering both the current findings and additional information on production practices in the industry.