Lamb Traits Research Articles

Peanut Cake as an Alternative Protein Source to Soybean Meal on Performance, Nitrogen Utilization, and Carcass Traits in Feedlot Lambs

Substituting soybean meal (SM) with other protein sources can be advantageous in reducing production costs without increasing nitrogen losses in the environment. Peanut cake (PC) might be a strategy in ruminant herds to result in a performance similar to that observed in animals fed SM. This study assessed the PC inclusion at rates of 0, 250, 500, 750, and 1000 g/kg on intake and digestibility, performance, nitrogen balance, microbial protein synthesis, and carcass traits of lambs. Forty-five entire, crossbreed Dorper × Santa Inês lambs (average age = five months and 24.49 ± 5.27 kg of BW) were distributed in a completely randomized design. Only the ether extract intake was not affected by the PC inclusion, and only the crude protein digestibility was affected by the diets. The total weight and average daily gains decreased, and the feed conversion increased. Hot carcass yield was influenced quadratically, the leg depth increased and the loin-eye area decreased. The total replacement of soybean meal with peanut cake in diets for lambs did not compromise nutrient digestibility, microbial protein synthesis, and carcass characteristics. Nevertheless, peanut cake as a protein source in the diet had adverse effects on nutrient intake and growth performance of feedlot lambs.

Dietary energy level and β2-adrenergic agonist supplementation on growth performance, dietary energy, carcass traits, and visceral mass of hairy lambs

Context The beta-agonist zilpaterol (ZH) is a feed additive that improves growth performance via protein accretion during the finishing phase of ruminant fattening. However, evaluating the possible interaction between ZH and nutrients of the diet has received limited attention. Aims We investigated the changes in growth performance and carcass traits in response to ZH supplementation of hairy lambs fed finishing diets with different energy concentration. Methods Forty-eight Pelibuey × Katahdin crossbred male lambs (43.8 ± 6.3 kg) were used in a 34-day feeding trial to evaluate the interaction between diet energy density [8.37 (LE) and 8.79 (HE) MJ of net energy for maintenance (NEm) per kilogram of diet] and zilpaterol hydrochloride supplementation (ZH, dosed at 0 or 6 mg ZH/kg) on growth performance, carcass traits, and visceral mass. All diets contained 14.5% crude protein (CP). Key results There was no interaction of energy level and ZH in any of the variables evaluated. HE increased average daily gain (ADG) and gain efficiency (GF) without affecting the observed-to-expected dietary NE. Zilpaterol supplementation increased ADG, GF, and observed-to-expected dietary NE. Both HE and ZH increased carcass weight. HE increased carcass fat, whereas ZH decreased it. HE increased dressing percentage. ZH increased longissimus muscle area, the muscle:fat ratio in the shoulder, and leg whole-cut proportion. Visceral mass was not affected by energy level. ZH decreased visceral fat. Conclusions Increasing diet energy from 8.37 to 8.79 MJ NEm/kg enhanced growth performance and carcass traits but did not improve dietary energy utilization. Supplemental ZH enhanced growth performance, dietary-energy utilization and carcass traits of lambs. Implications ZH supplementation is a tool to enhance growth performance by improving protein accretion and reducing carcass fat. Response to ZH supplementation is independent of the differences in energy density of finishing diets.

Encapsulated Butyric Acid and Zinc as a Feed Additive for Lambs Abruptly Transitioned to a Grain-Based Diet.

Butyric acid is attributed to gastrointestinal epithelial development and health and two studies were conducted to determine if supplementing encapsulated butyric acid and zinc (BZ) in lambs abruptly transitioned to a finishing diet has effects on growth performance, efficiency of dietary net energy utilization, rumen morphometrics, small intestinal histology, and carcass traits. Polypay wethers (n = 84; initial shrunk body weight = 38.8 kg ± 4.8 kg) were used in a randomized complete block design study. Wethers were abruptly transitioned from a high roughage-based diet to a 100% concentrate-based diet and dietary treatments were 0 or 2 g BZ/kg of diet dry matter. Study 1 evaluated growth performance and carcass traits of lambs over a 59.5 d feeding period, and Study 2 evaluated changes in rumen morphometrics and small intestine histology in serial harvested lambs. Wethers supplemented with BZ had increased body wall thickness, decreased calculated boneless closely trimmed retail cuts, and decreased red meat yield (p ≤ 0.03) compared to non-supplemented wethers. Linear effects (p ≤ 0.01) for harvest date were observed for most rumen and small intestine measurements. Supplementing wethers with BZ did not improve growth performance, carcass traits, or rumen and small intestine measurements. The effects of BZ supplementation on fat deposition in ruminants should be further investigated.

CORRELATION, REGRESSION COEFFICIENTS AND HERITABILITY BETWEEN MAIN SELECTION TRAITS OF SHEEP

The article presents information on improvement of selection traits of lambs born from "inbred" breeding of F2 crossbred sheep using selection-genetic indicators. Studies show that selection of lambs born from inbreeding of F2 hybrid sheep based on positive correlation coefficients between selection traits is important for creating high-yielding breeding flocks in the future. At the same time, the regression coefficients of crossbred lambs in group II were higher than the regression coefficients of pure jaidari lambs in group I, and especially it was found that the regression coefficients of crossbred rams in group II achieved the highest result. According to the heredity of the sheep, it was found that the live weight of the sheep, the height of the withers, the oblique length of the body, the width of the chest, the depth of the chest, the circumference of the udder, and the circumference of the calf, that is, the coefficients of heredity are moderate.

Effects of different rearing systems on carcase traits, physicochemical properties, basic chemical composition, fatty acid profiles and amino acid profiles of Gangba lamb

This study aimed to explore the influence of feeding regimens on carcase traits and meat quality of Gangba lambs. Thirty healthy Gangba ram lambs at nine months of age and an average body weight of 14.08 ± 0.79 kg were randomly distributed into three treatment groups (10 replicates per group). The groups are as follows: a grazing (G) group without any supplementation and housing; a semi-grazing (SG) group provided with 200–300 g of concentrates and free access to oat hay off-pasture; and a stall-feeding (SF) group with 400–500 g of concentrates and free access to oat hay. The experiment lasted 85 d, comprising a 10-d adaptation period and a 75-d experimental period. Results showed that significant differences in carcase weight existed among groups, respectively, with the SF group having the highest weights and the G group having the lowest weights (p < 0.05). The pH45min and pH24h in the G group were significantly higher than that in the SG group (p < 0.05). Muscles from the G and SG groups had higher erucic acid (22:1n-9), α-linolenic acid (C18:3n3), and conjugated linoleic acids (CLA-c9t11 and CLA-t10c12) than the SF group (p < 0.05). The G group had a lower concentration of proline (Pro) than the SF group (p < 0.05). In conclusion, the feeding systems had no effects on chemical composition and little influence on amino acid composition. The traditional grazing rearing and SG systems improved lamb meat quality by increasing the presence of beneficial fatty acids. In contrast, the SF regimen improved the carcase weight of Gangba lambs without increasing their meat quality compared to the grazing rearing and SG systems. The directions of future efforts for breeders are to improve carcase traits (like carcase weight) of lambs in both natural grazing and SG systems, as well as the meat quality of lambs raised in feedlots.

Evaluation of Some Reproductive Performance of Ewes, Livability and Growth Traits of Lambs of Akkaraman in Breeder Flocks in Niğde/Bor Province

Conducted within the National Sheep and Goat Breeding “subproject: Akkaraman Sheep Breeding Project under farmer conditions in Nigde’s Bor district” between 2018 and 2022, the current study evaluated the reproductive characteristics of ewes as well as the livability and growth traits of lambs. This study investigated some ‘reproductive traits’ of an average of 6000 ewes per year and ‘growth performance and ‘survival traits’ of a total of 30051 head lambs. The birth weight (LBW), 60th-day body weight (BW60), 120th-day body weight (BW120), and 120th-day body weight gain (BWG120) of Akkaraman lambs during the study periods were 4.14±0.19 kg, 18.58±0.03 kg, 31.31±0.02 kg, and 246±2.23 g/lamb/day, respectively. In the study, among the factors affecting the growth characteristics of Akkaraman lambs, only the effect of gender on BWG120 and birth type on BW120 was found to be insignificant. In contrast, the other factors were found to be found to be statistically significant. In the study, it was determined that the number of lambs per Akkaraman ewe giving birth between 2018-2022 varied between 1.03-1.10. The highest livability in Akkaraman lambs was determined in 2018 (96.61%) and the lowest in 2020 (83.21%). As a result, it was found that liveability in Akkaraman lambs was dependent on birth year, the age of the ewe, gender, and birth type.

Relationship of TRHDE Gene Polymorphism and Performance of Local Awassi Lambs

This study was conducted at the farm of animal production department / college of agricultural engineering sciences/ University of Baghdad, to detect the TRHDE gene polymorphism and its association with productive performance, daily gain, live weight gains and some characteristic of fat carcass on local Awassi lambs from 22/1/2022 to 2/4/2022. The experiment was conducted to study the effect of genetic polymorphism of the TRHDE gene on some nutritional traits in 40 Awassi lambs. There were three polymorphism appear in this variant (A>G SNP), which are AA, AG and GG, and their percentage was 70, 25, 5%, respectively. The results show that highly Significant (P≤0.01) with Polymorphism GG on total weight gain, While the wild genotype AA was superior to the genotype GG in feed conversion ratio and there no significant effect in carcass fat production. It can be concluded that the TRHDE gene polymorphism is related to the productive traits of Awassi lambs.

Performance, carcass characteristics and non-carcass components of Santa Ines and crossbred (Santa Ines x Dorper) lambs finished in different confinement strategies.

Genetic group, age at entry into confinement and at slaughter, are characteristics that have an important influence on lamb performance and carcass. The aim of this study was to evaluate the performance, carcass characteristics and non-carcass components from different genetic groups (Santa Inês and ½ Dorper x ½ Santa Inês) sheep, submitted to different feedlot entry and exit strategies. Were used 72 lambs males and castrated; 36 Santa Inês (SI) and 36 crossbred (Dorper x Santa Inês-DSI), with 6 months of average initial age. The groups were established in a completely randomized experimental design, in a 2x3x4 factorial arrangement, from the combination of genetic groups (GG), body weight at the beginning of confinement (WBC) and length of stay in confinement (LSC). The body weight classes at the beginning of confinement were: light (25 kg), intermediate (28 kg) and heavy (31 kg), for Santa Inês and crossbreeds, respectively. Slaughters were carried out every 28 days of confinement, in four LSC: 0, 28, 56 and 84 days. The GG did not influence performance, carcass and non-carcass component traits of lambs (p > 0.05). There was an effect of the WBC on the weights: final (FW), metabolic (MW), body at slaughter (BWS), empty body (EBW), hot carcass (HCY) and cold (CCW), loin, shoulder, leg musculature; loin eye area (LEA) and loin fat (p < 0.05). There was also an effect on LSC, for FW, average daily weight gain (ADG), MW, weight and yield of body components, weight of cuts and tissue ratio components of cuts (p < 0.05). In non-carcass components, effect on full and empty weight of: omasum, rumen-reticulum, small intestine; empty large intestine, liver and kidneys, paws and skin, and perirenal, pelvic and inguinal fat (p < 0.05). Interaction double effect on the tissue muscle/fat:bone ratio (MF:B) and for the full omasal component (p < 0.05). And triple interaction effect for ADG, full omasum and perirenal fat (p < 0.05). Weight at the beginning of confinement and confinement time are the characteristics that most influence performance, quantitative characteristics of carcass and non-carcass components. Regardless of the genetic group and age class, the animals reach the same weight after 84 days of confinement. Thus, the confinement of heavier lambs (31 kg) can be a profitable alternative, as they presented the highest weights for the most commercially valued cuts (shank and loin). The confinement strategy must adapt to market situations.

Potential use of vitiviniculture waste in mixed cactus pear silages with elephant grass in lamb diet

The aim was to evaluate intake, digestibility, water balance, nitrogen balance, ingestive behavior, performance, and carcass traits of lambs on diets containing levels of vitiviniculture waste in mixed cactus pear silages with elephant grass. Twenty-four crossbred male lambs (150 days of age, 20.75 kg ± 1.33 kg body weight) were assigned to a randomized block design, with four treatments (diets) and six animals per treatment. The experimental diets consisted of four elephant grass mixed silages (MS), containing different levels of cactus pear and vitiviniculture waste: MS1 – 255 g/kg cactus pear and 108 g/kg vitiviniculture waste; MS2 – 216 g/kg cactus pear and 144 g/kg vitiviniculture waste; MS3 – 180 g/kg cactus pear and 180 g/kg vitiviniculture waste; MS4 – 144 g/kg cactus pear and 216 g/kg vitiviniculture waste, on a dry matter basis (DM). The experiment lasted 86 days, preceded by 20 days of adaptation. The inclusion of vitiviniculture waste in silages resulted in a quadratic effect for intakes of crude protein, neutral detergent fiber, acid detergent fiber, and total carbohydrates, digestibility of DM and ether extract, metabolizable water, and water balance (P < 0.05), with the highest values of intake and digestibility observed in lambs fed on MS2. The MS in diets resulted in a reduction in the carcass conformation of the lambs (P = 0.034). Under the experimental conditions, the use of up to 144 g/kg vitiviniculture waste in the composition of mixed cactus pear and elephant grass silages (MS2) in diets for confined lamb as it provides greater nutrient intake and dry matter digestibility.

Discovering the hidden personality of lambs: Harnessing the power of Deep Convolutional Neural Networks (DCNNs) to predict temperament from facial images

The objective of this study was to define a more practical and reliable alternative to manual temperament classification methods that rely on the behavioral responses of animals individually subjected to various tests. Specifically, this study evaluated the correlation between facial image information and temperament based on deep convolutional neural networks (DCNNs) to predict the temperament of lambs based on their facial images. In the first phase, the lambs were categorized as to their temperament based on data acquired from a behavioral test to establish a ground truth for the temperament of the lambs. This enabled us to train (70%), validate (20%), and test (10%) deep-learning models in the second phase based on facial images and the corresponding temperament labels derived from the behavioral test. The performance of a custom deep convolutional neural network (C-DCNN) was compared to that of pre-trained VGG19 and Xception models for image classification. The Xception model achieved a training accuracy of 81%, which indicated that it learned well the underlying patterns in the data; however, lower validation (0.75) and test (0.58) accuracies indicate that it overfit the training data and did not generalize well to new samples. The VGG19 model, produced lower training (0.59), validation (0.46), and test (0.34) accuracies, which indicated that it did not learn the underlying patterns in the data as well as the Xception model. Furthermore, its precision (0.47), recall (0.42), and F1 score (0.41) indicated that the model performed poorly in identifying the classes correctly. The C-DCNN produced a moderate accuracy of 60%, which indicated that the model was able to predict the temperament traits of lambs with an accuracy of 60%, which was better than random guessing (33% accuracy), and demonstrated the potential of this approach in assessing temperament. The C-DCNN precision (0.69), recall (0.61) and F1 score (0.63) indicated that it had a moderate ability to correctly identify positive cases; however, the small size of the original dataset remains a limitation of the study because it might have caused the suboptimal performance of the models. To validate this approach, further research is needed based on a larger and more diverse dataset. We will continue to investigate the potential of deep learning and computer vision to predict animal personality traits from facial images based on large, diverse datasets, which might lead to more efficient and objective methods for assessing animal temperament and improving animal welfare.

Feed intake, digestibility, ruminal fermentation, growth performance, and carcass traits of lambs fed corn silage treated with Lentilactobacillus buchneri and stored for different times

Our objective was to investigate the impact of inoculation and storage length of flint corn silage on the metabolic and production responses of lambs. A flint corn hybrid was harvested with 315 g dry matter (DM)/kg and ensiled in concrete pipe silos without (control) or with Lentilactobacillus buchneri CNCM I-4323 at 1 × 105 cfu/g of fresh forage for 120, 240 and 360 d (n = 2 for each treatment). Such silages were used to formulate six different diets. Sixty non-castrated male Dorper × Santa Inês lambs were used in the feeding program (n = 10). Additionally, eight ruminally cannulated Dorper × Santa Inês crossbred lambs were used to measure the ruminal fermentation (n = 4). Extending the storage of corn silage from 120 to 360 d increased the contents of soluble protein (P = 0.030; 415–490 g/kg CP) and ammonia-N (P = 0.047; 82.5–114 g/kg total N). Compared to the control, inoculation resulted in higher (P < 0.05) concentration of lactic (+19.9 %) and acetic acid (+38.6 %), and lower butyric acid (–25.3 %), ammonia-N (–23.5 %), and DM loss (–36.2 %). The aerobic stability of corn silage was also improved by inoculation (P = 0.002; +160 h compared to the control). An interaction between storage length and inoculation was reported for feed intake, and lambs had increased DMI (P < 0.001) by feeding the inoculated silage stored for 120 d. Overall, the total-tract starch digestibility increased (P = 0.041) with longer storage (120 d = 94.4 %; 240 d = 95.7 %; 360 d = 96.5 %). However, the total VFA was unchanged (P > 0.05) while the ruminal molar proportion of propionate decreased from 22.8 to 20.7 mM/100 mM in lambs fed corn silage stored for 120 and 360 d (P = 0.004). Lengthening silage storage from 120 to 240 and 360 d tended (P = 0.06) to increase the ADG of lambs by 4.6 % and 10.2 %, respectively (120 d = 0.216 kg/d; 240 d = 0.226 kg/d; 360 d = 0.238 kg/d). Moreover, the feed efficiency was substantially improved (P = 0.008) by 5 % and 14 % when the silages were stored for 240 and 360 d compared to 120 d. In opposite, inoculation had no effect (P > 0.05) on ADG and feed efficiency of lambs. Final hot carcass weight (data ranged from 16.8 to 17.2 kg) and 12th rib longissimus muscle area (data ranged from 13.8 to 14.7 cm2) were not affected by treatments (P > 0.05). Overall, only few parameters of carcass and meat traits of lambs were altered by storage length and inoculation, but it were of minor biological importance. In conclusion, the productivity responses of lambs were enhanced by increasing the storage length of flint corn silage, but inoculation with L. buchneri did not contribute to improve animal performance.

Effect of genotype and environment on the productive and survivability traits of lambs under a community-based management system

The aim of this study was to evaluate the growth and survival of local and Dorper crossbred lambs managed under a community-based management system, using data collected between 2012 and 2021. The fixed effects considered were breed, location, sex, type of birth, parity, season, and year of birth. The results revealed that Dorper crossbred lambs consistently weighed and gained more than local lambs (p<0.0001) at all ages and that environmental factors such as location, sex, type of birth, parity, season, and year of birth had considerable influence on most growth traits at all ages. The mean birth weight of local, low-grade, and high-grade Dorper crossbred lambs were 2.12 ± 0.04, 2.94 ± 0.03, and 3.08 ± 0.03 kg, respectively. The corresponding pre-weaning daily gain was 89.12 ± 1.85, 112.16 ± 1.38, and 117.98 ± 1.71 g/day, respectively. The post-weaning body weight gain at 90-180 days for the same groups was 32.6 ± 2.16, 46.85 ± 1.62, and 45.93 ± 1.98 g/day, respectively. Dorper crossbred lambs exhibited a bodyweight advantage of up to 45%, 31%, 34%, and 28% over local lambs at birth, 3, 6, and 12 months of age, respectively. Lambs born in the dry season had the lowest weaning (p<0.0001) and six-month (p = 0.0098) weight compared to those born in the rainy seasons. Lamb genotype didn’t have a significant influence on the survival of lambs at all ages, but most environmental factors influenced survivability. Lambs born to ewes in their 5th parity and above had a mortality risk of 0.51 times higher than those born to ewes in their 1st to 4th parity at the age of 6- months. Year of lambing affected lamb pre-weaning (χ2 = 0.0003) and post-weaning (χ2 = 0.0001) survival. Compared to the base year 2021, lambs born in 2017 and 2018 had a higher risk of mortality at 6-month (10.1 and 15.9 times, respectively) than those born in 2021. Season of birth also significantly (χ2 <0.001) affected lamb survivability, with lambs born in the dry season, having a higher mortality risk at weaning (0.46 times) and yearling (0.66 times). Lambs with a birth weight of 2 kg and below had a 2.3 times higher survival risk at 6-months compared to lambs born with 3 kg and above. In conclusion, Dorper crossbred lambs can be considered to improve lamb growth performance and produce fast-growing lambs. However, the study recommends further research to validate the crossbreeding program (considering the influential production environment, research on supplementation for lambs in the dry-season, adjusting the mating season, and the economic feasibility of crossbreeding are suggested).

Effects of the breeding season, birth type and sex on growth and reproductive performances of sheep breeds.

The study aimed at determining the effects of breed type, breeding season, sex and type of birth on the growth and reproductive traits of lambs. Two ewe breed types (Gellaper and Swakara) and four ram breed types (Damara, Dorper, GeDo and Swakara) were used. Two lambing seasons, spring (March-May) and autumn (September-November), were considered. Gellaper-based lambs born in autumn had higher (P < 0.05) mean birth weight (4.58 kg) compared to spring-born lambs (3.43 kg). Ram lambs were heavier (P < 0.05) than ewe lambs at weaning and post-weaning age. Singletons were heavier than twins (P < 0.05) at birth, weaning and breeding. Single and autumn-born lambs had a higher average daily gain (ADG) than spring-born lambs (P < 0.05). Ram lambs had a higher pre-weaning and overall ADG (P < 0.05) compared with ewe lambs. Swakara-based lambs gained more from weaning to mating compared to Gellaper-based lambs (P < 0.05). The conception, lambing and annual reproductive rate were all influenced by breed type and season (P < 0.05). Swakara-based lambs had higher reproductive capabilities, while Gellaper-based lambs grew faster but take longer to breed type; autumn lambing gave rise to low birth weights but heavier lambs at weaning and post-weaning, hence suitable for mutton production.

Comparative energy value of cooked grease recovered from rinse-trap water lines used as dietary fat source for feedlot lambs

The objective of this experiment was to compare the effects of dietary supplementation with cooking grease recovered from rinse-trap water lines (rinse-trap grease; RTG) versus conventional supplemental fats (tallow; TL, and yellow grease; YG) on 84-d growth performance, dietary energy, and carcass traits of feedlot lambs. Forty-eight Pelibuey × Katahdin lambs (27.7 ± 3.4 kg) were assigned in a randomized complete block design to evaluate: 1) basal diet without supplemental fat (Control); 2) 4% TL; 3) 4% YG, and 4) 4% RTG. Supplemental fats replaced maize in the control diet. Rinse-trap grease contained greater moisture (16.5 vs 0.92%) and impurities (3.6 vs 0.56%), and less total fatty acid (64.90 vs 89.60%) than that of conventional fats (TL and YG). Daily weight gain and gain efficiency were similar for control and RTG supplemental lambs, whereas ADG and gain efficiency were greater for lambs fed conventional fats than control or RTG-supplemented lambs. Both dietary net energy (NE) as well as ratio of observed-to-expected dietary NE were 4% greater for lambs supplemented with conventional fats vs RTG. Supplemental fat increased fat deposition but did not affect any other carcass measures or non-fat visceral mass. Estimated NE value for RTG was 57% of the average NE value (6.11 Mcal/kg) of tested conventional fats. Supplementation with RTG does not affect diet acceptability, and accordingly, is a suitable energy source for feedlot lambs. However, due to its lower total fatty acid content, its energy value is much lower than conventional supplemental fats.

Estimates of Genomic Heritability and the Marker-Derived Gene for Re(Production) Traits in Xinggao Sheep.

Xinggao sheep are a breed of Chinese domestic sheep that are adapted to the extremely cold climatic features of the Hinggan League in China. The economically vital reproductive trait of ewes (litter size, LS) and productive traits of lambs (birth weight, BWT; weaning weight, WWT; and average daily gain, ADG) are expressed in females and later in life after most of the selection decisions have been made. This study estimated the genetic parameters for four traits to explore the genetic mechanisms underlying the variation, and we performed genome-wide association study (GWAS) tests on a small sample size to identify novel marker trait associations (MTAs) associated with prolificacy and growth. We detected two suggestive significant single-nucleotide polymorphisms (SNPs) associated with LS and eight significant SNPs for BWT, WWT, and ADG. These candidate loci and genes also provide valuable information for further fine-mapping of QTLs and improvement of reproductive and productive traits in sheep.

Maternal Rumen Bacteriota Shapes the Offspring Rumen Bacteriota, Affecting the Development of Young Ruminants.

The maternal rumen microbiota can affect the infantile rumen microbiota and likely offspring growth, and some rumen microbes are heritable and are associated with host traits. However, little is known about the heritable microbes of the maternal rumen microbiota and their role in and effect on the growth of young ruminants. From analyzing the ruminal bacteriota from 128 Hu sheep dams and their 179 offspring lambs, we identified the potential heritable rumen bacteria and developed random forest prediction models to predict birth weight, weaning weight, and preweaning gain of the young ruminants using rumen bacteria as predictors. We showed that the dams tended to shape the bacteriota of the offspring. About 4.0% of the prevalent amplicon sequence variants (ASVs) of rumen bacteria were heritable (h2 > 0.2 and P < 0.05), and together they accounted for 4.8% and 31.5% of the rumen bacteria in relative abundance in the dams and the lambs, respectively. Heritable bacteria classified to Prevotellaceae appeared to play a key role in the rumen niche and contribute to rumen fermentation and the growth performance of lambs. Lamb growth traits could be successfully predicted using some maternal ASVs, and the accuracy of the predictive models was improved when some ASVs from both dams and their offspring were included. IMPORTANCE Using a study design that enabled direct comparison of the rumen microbiota between sheep dams and their lambs, between littermates, and between sheep dams and lambs from other mothers, we identified the heritable subsets of rumen bacteriota in Hu sheep, some of which may play important roles in affecting the growth traits of young lambs. Some maternal rumen bacteria could help predict the growth traits of the young offspring, and they may assist in breeding of and selection for high-performance sheep.

Relationships between growth-related traits with carcass and meat quality traits in Spanish Assaf suckling lambs

Suckling lamb meat is a relevant product in Mediterranean European dairy sheep farms, and the dairy breed Spanish Assaf is widely extended through the Iberian Peninsula. Knowledge of the influence of birth body weight (bBW) and growth rate on suckling lamb carcass and meat quality is scarce, but useful for breeding optimisation and product homogeneity. In turn, these growth-related traits of lambs might be affected by dietary restrictions of their dams. In this study, 34 male Assaf suckling lambs born from two groups of ewes that had been fed diets with different protein levels when they were prepubertal female lambs (17 lambs per group) were analysed. After birth, the suckling lambs were fed ad libitum on milk replacer until their sacrifice (10–12.5 kg live body weight). The quality traits evaluated in carcasses and meat were carcass compactness, fatness and jointing, meat composition, colour, texture and oxidative stability, and fatty acid profile. The dam group did not show significant effects on lamb growth characteristics or carcass and meat quality traits. The bBW factor showed a negative effect on leg subcutaneous fatness and a positive effect on the forequarter and shoulder percentages of the carcass. The bBW also resulted in increased moisture, lipid oxidation stability, and n-3 FA content (lowering the n-6/n-3 ratio) in the meat. Suckling lambs showing very low average daily gain (ADG) tended to present low carcass quality, i.e., higher bone percentage in the loin and low percentages of muscle or fat compared to those showing high ADG. Further studies are needed to confirm and explain the mechanisms of the significant effects reported here for bBW and ADG on the affected quality traits.

An On-Station Analysis of Factors Affecting Growth Traits of Pure Red Maasai and Dorper Sheep Breeds under an Extensive Production System.

This comparative study aimed to evaluate genetic and environmental factors' effects on the growth traits of lambs in Dorper and Red Maasai (RedM) sheep breeds. The data analyzed contained the following measurements: birth weight (Bwt), weaning weight (Wwt), yearling weight (Ywt), birth type (single or twins), and details on each lamb's dam (dam ID and age) and sire. Except for the RedM, whose birth weight decreased with time, both breeds generally showed an increase in other growth weights across the study period, with yearly variations affecting both breeds. Additionally, analysis by a linear mixed model with restricted maximum likelihood (REML) showed that only breed as a factor significantly (p &lt; 0.05) influenced birth weight; breed, sex, and birth type all significantly (p &lt; 0.05) influenced weaning weight, whereas season, sex, and dam age significantly (p &lt; 0.05) influenced yearling weight. The RedM breed outperformed the Dorper breed in post-weaning growth rate, demonstrating early resilience and adaptation to local environmental factors independent of maternal influence. Breed and non-genetic factors play a vital role in the growth of lambs, and the results of this study offer an opportunity for improved farm management under an extensive production system and selection for the conservation of the indigenous Red Maasai breed.

Effect of weaning and feed provision times on the performance and several behavioural traits of post-weaning lambs.

The aim of the present study was to assess if weaning time (morning or evening) and feed provision (immediate or 4h delayed) can influence growth performance and expression of juvenile lamb behaviour immediately after and at the age of 50-125days old. Forty lambs were randomly assigned to 4 groups: E1 (evening + immediate), E2 (evening + delayed), M1 (morning + immediate) and M2 (morning + delayed). All lambs were especially active during the first hour after weaning. However, their activity within the first 24h after weaning was mainly affected by their circadian rhythms, since lambs were more active during the day compared to night. On the other hand, no effect of alfalfa hay provision on lamb activity during these first 24h was observed. At the age of 50-125days old, body weight was measured, and an isolation and flight distance test was implemented. There were no significant differences among lambs in body weight, number of jumps and heart rates assessed during isolation test and flight distance. However, the number of vocalizations was lower (65-110th day, P < 0.05) for the E2 compared to E1 lambs. Breed also slightly affected (95th day, P < 0.05) the average heart rate of lambs, with greater values for Karagouniko compared to Chios lambs. It is concluded that no discernible effects of weaning or feeding time were observed on growth performance and the display of stress-induced behavioural components of juvenile lambs till the age of 125days old.

Comparison of growth performance and carcass traits of native lambs in Bangladesh

The aim of this study was to compare the productive and carcass traits of native region lambs of Bangladesh. A total 30 lambs were taken for productive performances from three regions (Jamuna basin, Barind region and Coastal belt) and total 27 lambs were considered for evaluating carcass traits parameters for 3 treatment groups (T1= 6 months, T2= 9 months, T3=12 months). Statistical analysis was conducted by SAS where statistical model was 3×2(growth performance) and 3×3 (growth performance and carcass traits) factorial experimental model in Completely Randomized Design (CRD). Both sex and lamb types had significant effect (p&lt;0.05) on body weight at different ages. Among all lamb types, Coastal belt lamb(CBL) had the highest body weight (1.65, 6.55, 12.81, 15.59, and 19.97) kg followed by Jamuna basin lamb (JBL) (1.45, 6.51, 9.48, 13.86 and 17.21) kg and Barind region lamb (BRL) (1.5, 5.69, 8.88, 11.44 and 13.24) kg at birth, 3, 6, 9 and 12 months, respectively. The ADG was significantly higher in JBL and CBL (59.07 and 61.17g/d) than BRL (53.15 g/d). Dressing % was higher in later ages; 9 and 12 months (47.38 and 47.04%). Lamb types and slaughter ages had significant effect (p&lt;0.05) on blood, skin, viscera, head, leg, pluck, neck, shoulder, rack and loin wt. % except shank where only slaughter ages had significant effect but effect of lamb types was not statistically significant (p&gt;0.05). Lamb types (T), slaughter ages (L) and its interaction (T×L) had significant effect (p&lt;0.05) on kidney, liver, heart, lung and spleen wt%. The CBL showed superior performances over JBL and BRL in terms of overall body weight and their carcass traits parameters largely varied in different lamb types for different slaughter ages were the core findings of the present study.