Weaning Weight Research Articles

Negative energy balance affects perinatal ewe performance, rumen morphology, rumen flora structure, and placental function.

This study investigated the effects of negative energy balance (NEB) on perinatal ewes, with a focus on changes in growth performance, serum biochemical parameters, rumen fermentation, ruminal bacteria composition, placental phenotype-related indicators, and expression levels of genes related to placental function. Twenty ewes at 130 days of gestation were randomly allocated to either the positive energy balance (PEB) or NEB groups. In the experiment, ewes in the PEB group were fed the same amount as their intake during the pre-feeding baseline period, while ewes in the NEB group were restricted to 70% of their individual baseline feed intake. The experiment was conducted until 42 days postpartum, and five double-lamb ewes per group were selected for slaughter. The results demonstrated that NEB led to a significant decrease in body weight, carcass weight, and the birth and weaning weights of lambs (P < 0.05). Additionally, NEB caused alterations in serum biochemical parameters, such as increased non-esterified fatty acids and β-hydroxybutyrate levels and decreased cholesterol and albumin levels (P < 0.05). Rumen fermentation and epithelial parameters were also affected, with a reduction in the concentrations of acetic acid, butyric acid, total acid and a decrease in the length of the rumen papilla (P < 0.05). Moreover, NEB induced changes in the structure and composition of ruminal bacteria, with significant differences in α-diversity indices and rumen microbial community composition (P < 0.05). Gene expression in rumen papilla and ewe placenta was also affected, impacting genes associated with glucose and amino acid transport, proliferation, apoptosis, and angiogenesis (P < 0.05). These findings screened the key microbiota in the rumen of ewes following NEB and highlighted the critical genes associated with rumen function. Furthermore, this study revealed the impact of NEB on placental function in ewes, providing a foundation for investigating how nutrition in ewes influences reproductive performance. This research demonstrates how nutrition regulates reproductive performance by considering the combined perspectives of rumen microbiota and placental function.

Exploring the Economically Important Growth Traits and Environmental Influences on Akkaraman Lambs in Ankara

This study focused on the Akkaraman sheep breed, specifically examining the pre-weaning growth characteristics and Kleiber ratio, within the framework of Türkiye’s National Community-Based Small Ruminant Breeding Program. The research involved Akkaraman lambs born between 2017 and 2021 across 20 farms in the Ankara province. The dataset comprised 19,119 observations, covering key attributes such as birth weight, weaning weight, average daily weight gain, and the Kleiber ratio. Statistical analyses were conducted to identify outliers, assess normality, and develop linear models to explore the impact of environmental factors on the traits. Birth weight was significantly influenced by sex, birth type, birth season, birth year, and flock size. Weaning weight exhibited significant variations based on the same factors, emphasizing the importance of gender, birth type, birth season, birth year, and flock size. Average daily weight gain was notably affected by gender, birth type, birth season, birth year, flock size, and environmental factors, emphasizing their impact on growth. The Kleiber ratio demonstrated significant variations influenced by gender, birth type, birth season, birth year, and flock size. The results highlighted the intricate interplay between environmental factors and pre-weaning growth traits in the Akkaraman sheep breed. The study contributes valuable insights to enhance productivity and underscores the potential of the Akkaraman breed in Türkiye's overall agricultural development, considering its adaptability to arid climates and challenging pasture conditions

Investigation of Some Environmental Factors on Reproductive Characteristics, Milk Traits and Kleiber Ratios of Kilis Goats Reared in the Fertile Crescent of Türkiye

This study was carried out to determine the effect of environmental factors on some yield traits in Kilis goats. For this purpose, 6000 heads of Kilis goats each year, and a total of 30000 goats and kids born from them for 5 years, were the subject of the research. Milk control in goats was calculated by the ICAR-AT method. At the end of the study, Average birth weight was 3.56 kg, weaning weight was 15.06 kg and daily live weight gain was 191.64 g in kids. KR value found to be 23.6±0.03 in kids. Lactation milk yield in mothers was determined as 367.64 kg. As a result, it was determined that environmental factors were effective on the reproductive parameters and milk yield characteristics of Kilis goats and the developmental characteristics of kids. The crucial determination of these factors in the breeding of this breed will increase the accuracy of selection. In addition, the success will also be increased by starting the transition from the traditional breeding approach to the genomic breeding method and by combining these two strategies.

Performance evaluation of Indigenous and Garole crossbred sheep (F1) under semi-intensive management system

A crossbreeding program was sought to enhance the genetic attributes of coastal sheep by mating them with Garole rams. The breeding program involved a combination of two male Garole with a group of twenty indigenous ewes. These sheep were permitted to mate naturally, without external intervention. Data collection focused on key metrics like birth weight (kg lamb-1), litter size, sex of lambs, instances of dystocia, weaning weight (kg lamb-1), weaning age (days), body weight (kg), age at puberty (days), and mortality rates (%). Crossbred male lambs had an average birth weight of 1.48±0.12 kg, while female lambs averaged 1.57±0.10 kg. Male to female ratio among crossbred lambs was 54.1% to 45.9%. As for weaning, males and females averaged 151.92±2.24 days and 144.00±4.20 days, respectively, with respective weaning weights of 7.98±0.85 kg for males and 8.31±0.90 kg for females. Between 30 and 60 days, male and female lambs gained at 50.16±5.94 g day-1 and 51.44±7.82 g day-1, respectively. Between 331 and 360 days, growth rates were 15.33±3.84 g day-1 and 22.33±6.00 g day-1 for males and females respectively. Dystocia, or difficult births, occurred in 75% of cases. There was no mortality for male lambs, but female lambs experienced a 20% mortality rate. Crossbreeding has emerged as a viable strategy for increasing meat production due to enhanced growth rates and their adaptability to certain environments. It can be concluded that crossbreeding of indigenous coastal sheep with Garole ram can be carried out to increase body weight and ADG. Bangladesh Journal of Animal Science 53 (2): 55-67, 2024

Genomic Selection for Weaning Weight in Alpine Merino Sheep Based on GWAS Prior Marker Information.

This study aims to compare the accuracy of genomic estimated breeding values (GEBV) estimated using a genomic best linear unbiased prediction (GBLUP) method and GEBV estimates incorporating prior marker information from a genome-wide association study (GWAS) for the weaning weight trait in highland Merino sheep. The objective is to provide theoretical and technical support for improving the accuracy of genomic selection. The study used a population of 1007 highland Merino ewes, with the weaning weight at 3 months as the target trait. The population was randomly divided into two groups. The first group was used for GWAS analysis to identify significant markers, and the top 5%, top 10%, top 15%, and top 20% markers were selected as prior marker information. The second group was used to estimate genetic parameters and compare the accuracy of GEBV predictions using different prior marker information. The accuracy was obtained using a five-fold cross-validation. Finally, both groups were subjected to cross-validation. The study's findings revealed that the heritability of the weaning weight trait, as calculated using the GBLUP model, ranged from 0.122 to 0.394, with corresponding prediction accuracies falling between 0.075 and 0.228. By incorporating prior marker information from GWAS, the heritability was enhanced to a range of 0.125 to 0.407. The inclusion of the top 5% to top 20% significant SNPs from GWAS results as prior information into GS showed potential for improving the accuracy of predicting genomic breeding value.

The Comparative Study on Effect of Breed and Gender on Some Carcass Traits of New Zealand White and Dutch Rabbit Breeds

This study was designed to observe the effect of breed on some carcass traits of New Zealand White and Dutch rabbit breeds. In this study, 2 males and 8 female Breeder Rabbits from New Zealand White and Dutch rabbit breeds were purchased from a local farmer and allowed for breeding purposes by the ratio of 1:4 Male to Female in different cages. From the first filial generation, 80 kits were randomly selected after weaning at 21-25 days and grouped into A, B, C, and D. Groups A and C included males of New Zealand White and Dutch breeds, whereas B and D included females. Their live weight at 80 days was observed, and lastly, they were slaughtered to observe the effect of breed on carcass traits. Dutch breed males showed significantly higher (P&lt;0.05) weaning weight, live weight, slaughter weight, carcass weight, boneless weight, bone weight and dressing percentage compared to New Zealand White males, while Dutch females also exhibited higher traits compared to New Zealand White females. The results indicated that Dutch rabbits had higher birth weight, weaning weight, live weight, slaughter weight, carcass weight, boneless weight, bone weight, and dressing percentage as compared with New Zealand White breeds.

Weight Development and Growth Curves of Grazing Santa Inês Sheep Supplemented with Concentrate in the Pre-Weaning Phase.

Monitoring weight development is essential for decision-making and assessing the effectiveness of management strategies. However, this practice is often hindered by the lack of scales on farms. This study aimed to characterize the weight development and growth curves of male and female Santa Inês lambs from birth to weaning, managed on pasture with creep-fed concentrate supplementation. Data from 212 lambs during the pre-weaning phase were analyzed. The animals were weighed every seven days to evaluate total weight gain and average daily gain. Biometric measurements were taken every 28 days. Mixed models were used to assess the effects of sex and birth type on birth and weaning weights. Simple and multiple linear regression models were employed to estimate live weight using biometric measurements. The non-linear Gompertz model was utilized to describe weight development and formulate growth curves. Results were considered significant at p < 0.05. An interaction effect between birth type and sex (p < 0.05) was noted for birth weight, with the lowest weight observed in twin-birth females (2.96 kg) and the highest in single-birth males (3.73 kg) and females (3.65 kg) (p > 0.05). Birth type significantly influenced average daily gain, total weight gain, and weaning weight (p < 0.05). The Gompertz model accurately depicted the growth curves, effectively describing the weight development. Pearson's correlation coefficients between biometric measurements and weight were positive and significant (p < 0.05), ranging from 0.599 for hip height to 0.847 for heart girth. Consequently, the simple and multiple regression equations demonstrated high precision in predicting weaning weight. In conclusion, twin-birth lambs receiving concentrate supplementation via creep-feeding and managed on pasture showed different developmental patterns compared to single-birth lambs under the same conditions. The Gompertz model proved effective for monitoring development during the pre-weaning phase. All simple and multiple linear regression models were effective in predicting weaning weight through biometric measurements. However, for practical application, the model incorporating two measurements-body length and abdominal circumference-is recommended.

Estimation of Genetic Parameters for Early Growth Traits in Luzhong Mutton Sheep

In this study, six different animal models were fitted, and the constrained maximum likelihood method was used to assess the genetic parameters and genetic trends of early growth traits in Luzhong mutton sheep. The experimental data of this study included the newborn weight (BWT, N = 2464), weaning weight (WWT, N = 2923), weight at 6 months of age (6WT, N = 2428), average daily weight gain from birth to weaning (ADG1, N = 2424), and average daily weight gain from weaning to 6 months of age (ADG2, N = 1836) in Luzhong mutton sheep (2015~2019). The best model for the genetic parameters of the five traits in Luzhong mutton sheep was identified as Model 4 using the Akaike information criterion (AIC) and likelihood ratio test (LRT) methods, in which the estimated values of direct heritability for the BWT, WWT, 6WT, ADG1, and ADG2 were 0.156 ± 0.057, 0.547 ± 0.031, 0.653 ± 0.031, 0.531 ± 0.035, and 0.052 ± 0.046, respectively, and the values for maternal heritability were 0.201 ± 0.100, 0.280 ± 0.047, 0.197 ± 0.053, 0.275 ± 0.052, and 0.081 ± 0.092, respectively. The genetic correlation between the ADG2 and WWT was negative, and the genetic and phenotypic correlations among the remaining traits were positive. In this study, maternal effects had a more significant influence on early growth traits in Luzhong mutton sheep. In conclusion, to effectively improve the accuracy of genetic parameter estimation, maternal effects must be fully considered to ensure more accurate and better breeding planning.

Fertility and Some Growth Characteristics of Lambs in Akkaraman Sheep Grown in Çorum Province

Objective: The aim of this study was to determine the reproductive efficiency and lamb growth characteristics of Akkaraman sheep in Çorum province under breeder conditions. Material and Methods: The animal material of the study consisted of 2214 Akkaraman sheep and 2508 Akkaraman lambs from three different farms located in the center of Çorum province. The study was conducted between 2019 and 2022. In the study, reproductive characteristics of Akkaraman sheep and birth, weaning live weights, and survival of lambs were determined. Results: The mean birth weight of lambs was 4.15 kg, and the mean weaning weight (75th day) was 19.58 kg. Birth and weaning weights differed according to year, farm, type of birth, and sex (P

Weighted single-step genome-wide association study for direct and maternal genetic effects associated with birth and weaning weights in sheep

Body weight is an important economic trait for sheep meat production, and its genetic improvement is considered one of the main goals in the sheep breeding program. Identifying genomic regions that are associated with growth-related traits accelerates the process of animal breeding through marker-assisted selection, which leads to increased response to selection. In this study, we conducted a weighted single-step genome-wide association study (WssGWAS) to identify potential candidate genes for direct and maternal genetic effects associated with birth weight (BW) and weaning weight (WW) in Baluchi sheep. The data used in this research included 13,408 birth and 13,170 weaning records collected at Abbas-Abad Baluchi Sheep Breeding Station, Mashhad-Iran. Genotypic data of 94 lambs genotyped by Illumina 50K SNP BeadChip for 54,241 markers were used. The proportion of variance explained by genomic windows was calculated by summing the variance of SNPs within 1 megabase (Mb). The top 10 window genomic regions explaining the highest percentages of additive and maternal genetic variances were selected as candidate window genomic regions associated with body weights. Our findings showed that for BW, the top-ranked genomic regions (1 Mb windows) explained 4.30 and 4.92% of the direct additive and maternal genetic variances, respectively. The direct additive genetic variance explained by the genomic window regions varied from 0.31 on chromosome 1 to 0.59 on chromosome 8. The highest (0.84%) and lowest (0.32%) maternal genetic variances were explained by genomic windows on chromosome 10 and 17, respectively. For WW, the top 10 genomic regions explained 6.38 and 5.76% of the direct additive and maternal genetic variances, respectively. The highest and lowest contribution of direct additive genetic variances were 1.37% and 0.42%, respectively, both explained by genomic regions on chromosome 2. For maternal effects on WW, the highest (1.38%) and lowest (0.41%) genetic variances were explained by genomic windows on chromosome 2. Further investigation of these regions identified several possible candidate genes associated with body weight. Gene ontology analysis using the DAVID database identified several functional terms, such as translation repressor activity, nucleic acid binding, dehydroascorbic acid transporter activity, growth factor activity and SH2 domain binding.

Supplementing Monosodium Glutamate in Sow Diets Enhances Reproductive Performance in Lactating Sows and Improves the Growth of Suckling Piglets.

In most current farm operations, lactating sows need to overcome reproductive and environmental stresses that have resulted in poor sow production performance and piglet growth. Therefore, this study aimed to investigate the effects of in-feed supplementation of monosodium glutamate (MSG) in sows during late gestation lactation in regard to litter performance. The study subjects were 12 multi-parity sows (Landrace × Large White), farrowing sows with an average parity of four (three with three parities, seven with four parities, and two with five parities). They were randomly divided into the following two diet groups: the basal diet as a control (CON) group based on corn and soybean meal; and the basal diet + 2% MSG group. The experimental time ranged from 109 days before delivery to 21 days after delivery. There were six sows in each group, and each sow served as the experimental unit. There were no significant differences (p > 0.05) in body weight (BW), back fat (BF) thickness and estrus interval between sows supplemented with 2% MSG in their diets before and after farrowing and during weaning (p > 0.05). However, MSG-treated sows tended to increase BW loss at farrowing more than the CON group (p = 0.093) but lost less weight during lactation than the CON group (p = 0.019). There were no significant differences in the body condition scores (BCSs) and BF loss of the two groups of sows before and after farrowing and at weaning (p > 0.05). There was no significant difference in the weight of newborn piglets between the two groups of sows (p > 0.05). The weaning weight (p = 0.020) and average daily gain (ADG) (p = 0.045) of suckling piglets were higher in the MSG treated group compared to the CON group. The daily milk production of sows in the MSG treatment group was higher compared to the CON group (p = 0.045). The protein concentration of milk at week 3 (p = 0.060) and fat concentration of milk at week 5 (p = 0.095) of the MSG-supplemented sows tended to increase more than the CON group. In summary, the dietary inclusion of MSG supplementation had a beneficial effect on the late gestating sows and their piglet's growth and milk production. Our research has shown that the addition of 2% MSG in late gestation and lactation diet would be beneficial for both sow and piglet production.

Genome-Wide Gene-Environment Interaction Analysis Identifies Novel Candidate Variants for Growth Traits in Beef Cattle.

Complex traits are widely considered to be the result of a compound regulation of genes, environmental factors, and genotype-by-environment interaction (G × E). The inclusion of G × E in genome-wide association analyses is essential to understand animal environmental adaptations and improve the efficiency of breeding decisions. Here, we systematically investigated the G × E of growth traits (including weaning weight, yearling weight, 18-month body weight, and 24-month body weight) with environmental factors (farm and temperature) using genome-wide genotype-by-environment interaction association studies (GWEIS) with a dataset of 1350 cattle. We validated the robust estimator's effectiveness in GWEIS and detected 29 independent interacting SNPs with a significance threshold of 1.67 × 10-6, indicating that these SNPs, which do not show main effects in traditional genome-wide association studies (GWAS), may have non-additive effects across genotypes but are obliterated by environmental means. The gene-based analysis using MAGMA identified three genes that overlapped with the GEWIS results exhibiting G × E, namely SMAD2, PALMD, and MECOM. Further, the results of functional exploration in gene-set analysis revealed the bio-mechanisms of how cattle growth responds to environmental changes, such as mitotic or cytokinesis, fatty acid β-oxidation, neurotransmitter activity, gap junction, and keratan sulfate degradation. This study not only reveals novel genetic loci and underlying mechanisms influencing growth traits but also transforms our understanding of environmental adaptation in beef cattle, thereby paving the way for more targeted and efficient breeding strategies.

Comparison of genomic prediction methods for early growth traits of Inner Mongolia cashmere goats based on multi trait models.

Inner Mongolia cashmere goat is an excellent livestock breed formed through long-term natural selection and artificial breeding, and is currently a world-class dual-purpose breed producing cashmere and meat. Multi trait animal model is considered to significantly improve the accuracy of genetic evaluation in livestock and poultry, enabling indirect selection between traits. In this study, the pedigree, genotype, environment, and phenotypic records of early growth traits of Inner Mongolia cashmere goats were used to build multi trait animal model., Then three methods including ABLUP, GBLUP, and ssGBLUP wereused to estimate the genetic parameters and genomic breeding values of early growth traits (birth weight, weaning weight, average daily weight gain before weaning, and yearling weight). The accuracy and reliability of genomic estimated breeding value are further evaluated using the five fold cross validation method. The results showed that the heritability of birth weight estimated by three methods was 0.13-0.15, the heritability of weaning weight was 0.13-0.20, heritability of daily weight gain before weaning was 0.11-0.14, and the heritability of yearling weight was 0.09-0.14, all of which belonged to moderate to low heritability. There is a strong positive genetic correlation between weaning weight and daily weight gain before weaning, daily weight gain before weaning and yearling weight, with correlation coefficients of 0.77-0.79 and 0.56-0.67, respectively. The same pattern was found in phenotype correlation among traits. The accuracy of the estimated breeding values by ABLUP, GBLUP, and ssGBLUP methods for birth weight is 0.5047, 0.6694, and 0.7156, respectively; the weaning weight is 0.6207, 0.6456, and 0.7254, respectively; the daily weight gain before weaning was 0.6110, 0.6855, and 0.7357 respectively; and the yearling weight was 0.6209, 0.7155, and 0.7756, respectively. In summary, the early growth traits of Inner Mongolia cashmere goats belong to moderate to low heritability, and the speed of genetic improvement is relatively slow. The genetic improvement of other growth traits can be achieved through the selection of weaning weight. The ssGBLUP method has the highest accuracy and reliability in estimating genomic breeding value of early growth traits in Inner Mongolia cashmere goats, and is significantly higher than that from ABLUP method, indicating that it is the best method for genomic breeding of early growth weight in Inner Mongolia cashmere goats.

Comparison of different animal models for estimating genetic parameters for early growth traits and reproductive traits in Tianmu Sainuo sheep.

As the economic level of individuals rises, so too does the demand for mutton. Enhancing the breeds of mutton sheep not only boosts production efficiency and economic benefits but also fosters the sustainable growth of the mutton sheep breeding industry. Thus, this study examines the early growth and reproductive traits of Tianmu Sainuo sheep, analyzing the genetic interactions among these traits to furnish a theoretical foundation for refining breeding strategies and expediting the genetic advancement of this breed. The investigation compiled 29,966 data entries, involving 111 sires for birth weight (BWT) and 113 for other metrics. The data encompassed 10,415 BWT records from 1,633 dams, 12,753 weaning weight (WWT) records from 1,570 dams, 12,793 average daily gain (ADG) records from 1,597 dams, and 13,594 litter size (LS) records from 1,499 dams. Utilizing the GLM procedure in SAS 9.2 software, the study analyzed the non-genetic influences on lamb BWT, WWT, ADG, and LS. Concurrently, DMU software estimated the variance components across various animal models for each trait. Employing the Akaike Information Criterion (AIC) and likelihood ratio test (LRT), six models were tested, incorporating or excluding maternal inheritance and environmental impacts, to identify the optimal model for deriving genetic parameters. The findings reveal that birth year (BY), birth quarter (BQ), birth type (BT), age of mother (AM), and birth sex (BS) exerted significant impacts on BWT, WWT, and ADG (p < 0.01). Additionally, BQ and AM significantly influenced LS (p < 0.01). The most accurate genetic evaluation model determined the heritability of BWT, WWT, ADG, and LS to be 0.0695, 0.0849, 0.0777, and 0.1252, respectively.

The Environmental Impact on Economically Significant Traits in Central Anatolian Merino Sheep

This research delves into the pre-weaning growth and fleece characteristics of the Central Anatolian Merino sheep breed, focusing on Türkiye's National Community-Based Small Ruminant Breeding Program. The study encompasses Central Anatolian Merino lambs born between 2016 and 2021 across 22 farms in Ankara province, amassing a dataset of around 35,344 observations. Economically important traits such as birth weight (BW), weaning weight (WW), average daily weight gain (ADWG), Kleiber ratio at weaning (KR), fibre diameter, and fibre length (measured in approximately 4,809 observations) were scrutinized. Rigorous statistical analyses, including outlier identification, normality assessment, and the development of linear mixed models, were employed to unravel the impact of environmental factors on these traits. Significant findings emerged, indicating that birth weight, weaning weight, and the Kleiber ratio were substantially influenced by variables such as sex, birth type, birth season, birth year, and flock size. Moreover, average daily weight gain exhibited noteworthy variations attributed to gender, birth type, birth season, birth year, flock size, and other environmental factors, underscoring their collective impact on growth. Fleece traits displayed considerable diversity influenced by gender, birth type, birth season, birth year, and flock size. This study sheds light on the intricate interplay between environmental factors and pre-weaning growth traits within the Central Anatolian Merino sheep breed. Beyond its scientific contributions, this research provides valuable insights aimed at bolstering productivity. The adaptability of the Central Anatolian Merino breed to arid climates and challenging pasture conditions positions it as a key player in Türkiye's broader agricultural development.

Sexual dimorphism in the environmental sensitivity of weaning weight in beef cattle

This study investigates the environmental sensitivity and sexual dimorphism in the genetic parameters of weaning weight (WW) in Nelore beef cattle. Five reaction norms models were employed to analyze the 148,131 WW records, considering different definitions of the environmental descriptor (ED). (Co)variance components and genetic parameters were separately estimated for males and females. Results reveal substantial sexual dimorphism in various parameters. Significant divergence across sexes was observed for environmental sensitivity, with males showing an increased response to favorable environments while females genetically responded better to more challenging environments. Including sex in defining the ED can inflate the estimated breeding values of sires with a higher number of male progeny records, highlighting the importance of choosing a reliable ED in analyses of traits influenced by sexual dimorphism and genotype-by-environment interaction (G × E). The observed sexual dimorphism and environmental sensitivity underscore the complexity of genetic evaluation of WW in beef cattle populations, with implications for selection strategies. The findings suggest that a sex-separated trait analysis considering G × E effects is most appropriate for genetic evaluations of WW. However, a simpler single-trait model excluding sex from the ED definition yielded a higher coincidence of selected sires with the sex-separated analysis. In conclusion, understanding sexual dimorphism and environmental sensitivity is crucial for genetic evaluations and selection decisions in beef cattle breeding programs, emphasizing the need for careful model selection and ED definition.

Early growth performance in the Murciano-Granadina goats: insights from genetic and phenotypic analyses

Abstract This study investigates the genetic and phenotypic aspects of early growth performance in the Murciano-Granadina goat breed, using data collected between 2016 and 2022 from a private dairy farm in Ghale-Ganj city, located in the southern area of Kerman province, Iran. Pedigree and data information were collected on several early body weight traits, including birth weight (BW), weaning weight (WW), average daily gain (ADG), Kleiber ratio (KR) and growth efficiency from birth to weaning (GE). Nine univariate animal models included direct additive genetic effects and different combinations of maternal effects were compared by using Akaike information criterion (AIC). Among the tested models, the best genetic analysis model for BW, included direct additive, maternal additive, maternal permanent and maternal temporary environmental effects. The best model for ADG, KR and GE included direct additive, maternal permanent and litter effects. For WW, the best model was determined to be one that included direct additive and maternal additive genetic effects. The estimated direct heritabilities were low values of 0.04, 0.07, 0.08, 0.05 and 0.07 for BW, ADG, KR, GE and WW, respectively. The estimates of genetic correlations among the studied traits were positive and low to high in magnitude which ranged from 0.11 for BW-KR to 0.91 for BW-GE. The phenotypic correlations ranged from 0.03 for KR-WW to 0.87 for ADG-KR. The positive correlations observed among the studied growth traits of the Murciano-Granadina goat breed indicate no negative genetic or phenotypic changes associated with selection for these traits.

Hourly Feeding Regime of Modern Genetics Lactating Sows: Enhancing Productive Performance, Welfare, and Piglet Growth in Smart Farm-Based Systems

Effective management of lactating sows significantly influences various aspects of swine production. This study compared the impact of an hourly feeding regime and a five-times-daily feeding regime on the productive performance, body condition, and welfare of lactating sows, as well as on the growth performance of their offspring. Twenty-eight lactating sows (Landrace × Yorkshire) were divided into two groups: Group 1 was fed five times a day, and Group 2 was fed according to an hourly regime. The data were analyzed using independent-samples T-tests and the Mann–Whitney U test using Statistical Analysis System (SAS, 2011, Version 9.3) software. An hourly feeding regime positively affected (p &lt; 0.05) sows’ feed intake and body condition, significantly reducing the days from the weaning-to-estrus interval. Group 1 exhibited significantly higher (p &lt; 0.05) reductions in backfat thickness (BFT) and body condition score (BCS) during the weaning period compared to Group 2. Additionally, significant differences (p &lt; 0.05) were observed in regard to sow body weight loss, feed intake, piglet livability and mortality rate at weaning, sow index, and calculated milk yield. Feeding sows according to an hourly regime positively impacted their productive performance compared to those fed five times daily. No significant differences (p &gt; 0.05) were recorded in regard to the total number of piglets born, live births, mummified piglets, stillbirths, piglet mortality, litter size at weaning, and sow feed conversion ratio (FCR). However, the number of piglets weaned per sow per year (PSY) was numerically higher in Group 2 (p &gt; 0.05). The piglets from Group 2 had significantly higher (p &lt; 0.05) weaning weights and exhibited lower feed intake, greater weight gain, improved average daily gain, and greater litter size weight gain than those from Group 1. Statistically, sows from Group 2 exhibited a higher frequency of standing (p &lt; 0.05), which potentially contributed to the reduction in shoulder skin lesions in sows (p &gt; 0.05). In conclusion, an hourly feeding regime could optimize sow productive performance, body condition, milk yield, welfare, and piglet growth in swine production.

Estimation of genetic parameters for maintenance energy requirements and residual feed intake in Nellore cattle.

We estimated heritabilities and genetic and phenotypic correlation estimates for maintenance energy requirements (NEmR), residual feed intake (RFI), growth, carcass and reproductive indicator traits, using data from 41 feed efficiency trials in Brazil, comprising 4381 males and females. Continuous traits were analysed using a linear animal model and threshold traits were analysed using a threshold animal model. The heritability estimates were low for RFI (0.190) and NEmR (0.193); other heritabilities were mainly moderate (growth and carcass traits) or high (sexual precocity traits). The genetic correlation of RFI with NEmR was high (0.701). The genetic correlations of NEmR were low with carcass and reproductive traits, and moderate with growth traits. Thus, selection to improve weaning weight and female sexual precocity indicator traits would not affect maintenance energy requirement. Genetic selection to reduce maintenance energy requirements is feasible and would also reduce DMI and RFI. Selection to improve RFI can be used to identify animals with lower maintenance energy requirements. Long-term selection to reduce RFI and NEmR would have favourable effects on yearling weight, carcass muscle indicator traits and female sexual precocity. Genetic (co)variance component estimates for NEmR, in conjunction with economic values of selection criteria, may be used to develop novel approaches for genetic selection to improve efficiency of beef production.

217 Weaning weight associated with improved nursery pig growth rate

Abstract Heavier body weight (BW) at weaning is associated not only with heavier birth weight, but also with heavier downstream BW at nursery exit and at fixed-time marketing. To further address management implications of wean weight (WW), this study evaluated WW impact on nursery pig start-up, gain to feed ratio (G:F), and performance variation from 6 to 20 kg BW. Individual BW were collected at the time of weaning using the LeeO individual animal identification system. Pigs (n = 1,054; PIC 800 x DNA 241 F1) were blocked by wean age (20.1 ± 0.8 d) and sex, ranked in order of individual WW (5.94 ± 1.35 kg), and split into eight WW groups each representing 12.5% of the weaning population (P &amp;lt; 0.05; Table 1). Similar sized pigs were housed together (12 pigs/pen, 11 replicate pens/WW group) and fed a common 4-phase nursery diet for 42 d post-wean. Pen weights and feed disappearance were recorded at d 7, 14, 21, and 42, and individual BW were collected at d 42. Data were analyzed using linear mixed effects models in the lme4 package of R. Body weight differences (P &amp;lt; 0.05) between each WW group were evident on d 0 and through d 7 post-weaning. The lightest 12.5% of the weaning population had the greatest (P &amp;lt; 0.001) individual pig BW coefficient of variation (CV) at weaning and d 42 whereas no differences (P &amp;gt; 0.05) in d 42 BW CV were evident among the other WW groups. During the first week post-weaning, average daily feed intake (ADFI) diverged (P &amp;lt; 0.05) between the lightest 12.5% (113 g/d) and the heaviest 25% (134 g/d) of the wean population. From d 0 to 42, the lightest 12.5% WW pigs had slower average daily gain (ADG; P &amp;lt; 0.001), less ADFI (P &amp;lt; 0.001), and reduced exit BW (P &amp;lt; 0.001) than the other WW groups. Neither ADG nor ADFI differed (P &amp;gt; 0.05) among the median 50% of the population from d 0 to 42. No differences (P &amp;gt; 0.10) in overall nursery G:F between any WW groups were observed. Across the population, regression analysis indicated a 0.45 kg increase in WW resulted in a 1.0 kg increase (linear, P &amp;lt; 0.001) in nursery exit BW. Moreover, both ADG and ADFI as a percentage of BW increased as WW decreased, suggesting lighter WW pigs have competitive growth capacity to their heavier WW counterparts through 20 kg BW. Data demonstrates WW influences nursery exit weight of pigs fed a common diet. Future research should explore solutions to increase growth rate of light WW pigs.