Post-weaning Average Daily Gain Research Articles

Inbreeding depression and runs of homozygosity islands in Asturiana de los Valles cattle breed after 30 years of selection.

Inbreeding depression results in a decrease in the average phenotypic values of affected traits. It has been traditionally estimated from pedigree-based inbreeding coefficients. However, with the development of single-nucleotide polymorphism arrays, novel methods were developed for calculating the inbreeding coefficient, and consequently, inbreeding depression. The aim of the study was to analyse inbreeding depression in 6 growth and 2 reproductive traits in the Asturiana de los Valles cattle breed using both genealogical and molecular information. The pedigree group comprised 225,848 records and an average equivalent number of complete generations of 2.3. The molecular data comprised genotypes of 2693 animals using the Affymetrix medium-density chip. Using the pedigree information, three different inbreeding coefficients were estimated for the genotyped animals: the full pedigree coefficient (FPED ), and the recent and ancient inbreeding coefficients based on the information of the last three generations (FPED<3G ) and until the last three generations (FPED>3G ), respectively. Using the molecular data, seven inbreeding coefficients were calculated. Four of them were estimated based on runs of homozygosity (ROH), considering (1) the total length (FROH ), (2) segments shorter than 4 megabases (FROH<4 ), (3) between 4 and 17 megabases (FROH4-17 ), and (4) longer than 17 Mb (FROH>17 ). Additionally, the three inbreeding coefficients implemented in the Plink software (FHAT1-3 ) were estimated. Inbreeding depression was estimated using linear mixed-effects model with inbreeding coefficients used as covariates. All analysed traits (birth weight, preweaning average daily gain, weaning weight adjusted at 180 days, carcass weight, calving ease, age at first calving, calving interval) showed a statistically significant non-zero effect of inbreeding depression estimated from the pedigree group, except for the Postweaning Average Daily Gain trait. When inbreeding coefficients were based on the genomic group, statistically significant inbreeding depression was observed for two traits, Preweaning Average Daily Gain and Weaning Weight based on FROH , FROH>17 , and FHAT3 inbreeding coefficients. Nevertheless, similar to inbreeding depression estimated based on pedigree information, estimates of inbreeding depression based on genomic information had no relevant economic impact. Despite this, from a long-term perspective, genotyped data could be included to maximize genetic progress in genetic programs following an optimal genetic contribution strategy and to consider individual inbreeding load instead global inbreeding. ROH islands were identified on chromosomes 2, 3, 8, 10, and 16. Such regions contain several candidate genes for growth development, intramuscular fat, body weight and lipid metabolism that are related to production traits selected in Asturiana de los Valles breed.

Non-genetic factors affecting pre and post-weaning average daily gain in Sirohi goat under field condition

Non-genetic factors affecting pre and post-weaning average daily gain in Sirohi goat under field condition

170 Bakery Waste Supplementation to Late Gestating Bos Indicus-Influenced Beef Cows Successfully Impacted Offspring Postnatal Performance

Abstract This study evaluated the growth and immune function of Bos indicus-influenced offspring born to cows offered prepartum supplementation of bakery waste containing 2 concentrations of crude fat. On day 0 (~90 d before calving), 108 Brangus crossbred cows were stratified by body weight (BW; 551 ± 65 kg) and body condition score (BCS, 5.5 ± 0.9) and were randomly allocated into 1 of 18 bahiagrass pastures (6 cows and 4.3 ha/pasture). Treatments were randomly assigned to pastures (6 pastures/treatment) and consisted of no prepartum supplementation (NOSUP) and 1 kg/d of low-fat (LFAT; 6.4% crude fat) or high-fat (HFAT; 10.7% crude fat) bakery waste-based supplement from day 0 to 70. Calves were weaned on day 292. Then, 15 heifers/treatment were randomly selected, acclimated for 7 d, and assigned to drylot pens from day 300 to 345. Heifers were vaccinated against respiratory pathogens on days 300 and 315. Cow BCS on day 70 was the least (P ≤ 0.05) for NOSUP cows and did not differ (P ≥ 0.12) between LFAT and HFAT cows. Cow BCS on day 140 (start of breeding season) was greater (P = 0.05) for HFAT vs. NOSUP cows and intermediate (P ≥ 0.35) for LFAT cows. Plasma concentrations of total polyunsaturated fatty acids (PUFA) in HFAT cows did not differ (P ≥ 0.76) compared with LFAT cows on day 70, were greater (P ≤ 0.05) compared with NOSUP cows on day 70 and were the greatest on day 140 (P ≤ 0.05). Percentage of cows pregnant on day 292 did not differ (P ≥ 0.26) among treatments but more HFAT cows calved (P ≤ 0.05) their second offspring from day 429 to 450 compared with NOSUP and LFAT cows. First offspring BW on day 292 were greatest (P ≤ 0.05) for LFAT calves and least for NOSUP calves. Maternal treatments did not impact (P ≥ 0.11) post-weaning average daily gain (ADG) and total DM intake. Average plasma cortisol concentrations were greater (P = 0.03) for NOSUP vs. HFAT heifers and intermediate for LFAT heifers (P ≥ 0.26). Final serum titers against infectious bovine rhinotracheitis (IBR) and bovine respiratory syncytial virus (BRSV) were greater (P ≤ 0.08) for LFAT vs. HFAT heifers and intermediate (P ≥ 0.27) for NOSUP heifers. Therefore, crude fat concentration in bakery waste offered to late-gestating beef cows had variable effects on offspring performance. Low-fat bakery waste led to greatest offspring preweaning growth whereas high-fat bakery waste enhanced maternal reproductive success and offspring post-weaning humoral immune response.

Preweaning period is a critical window for rumen microbial regulation of average daily gain in Holstein heifer calves.

Rumen bacterial groups can affect growth performance, such as average daily gain (ADG), feed intake, and efficiency. The study aimed to investigate the inter-relationship of rumen bacterial composition, rumen fermentation indicators, serum indicators, and growth performance of Holstein heifer calves with different ADG. Twelve calves were chosen from a trail with 60 calves and divided into higher ADG (HADG, high pre- and post-weaning ADG, n = 6) and lower ADG (LADG, low pre- and post-weaning ADG, n = 6) groups to investigate differences in bacterial composition and functions and host phenotype. During the preweaning period, the relative abundances of propionate producers, including g_norank_f_Butyricicoccaceae, g_Pyramidobacter, and g_norank_f_norank_o_Clostridia_vadinBB60_group, were higher in HADG calves (LDA > 2, P < 0.05). Enrichment of these bacteria resulted in increased levels of propionate, a gluconeogenic precursor, in preweaning HADG calves (adjusted P < 0.05), which consequently raised serum glucose concentrations (adjusted P < 0.05). In contrast, the relative abundances of rumen bacteria in post-weaning HADG calves did not exert this effect. Moreover, no significant differences were observed in rumen fermentation parameters and serum indices between the two groups. The findings of this study revealed that the preweaning period is the window of opportunity for rumen bacteria to regulate the ADG of calves.

PSI-A-5 Effects of Birth Body Weight Classification on Heifer Growth, Dry Matter Intake, Feed Efficiency, and Grazing Performance

Abstract The objective was to evaluate the effect of birth body weight (BBW) classification on post-weaning growth, dry matter intake (DMI), feed efficiency, and grazing performance of fall-born crossbred heifers. Heifers were classified based on BBW as either light (LtBBW, &amp;lt; -0.5 SD from mean), average (AvgBBW, ± 0.5 SD from mean), or heavy (HvyBBW, &amp;gt; +0.5 SD from mean). Angus and Hereford-sired heifers (n = 153) from commercial Angus dams were utilized in the analysis. Heifers were early weaned at 82 ± 7 days of age. Post-weaning management strategy consisted of calves being kept in partially covered drylot pens and fed a high-energy grain diet (35% dried distillers grains with solubles, 30% whole shelled corn, 30% ground fescue hay, and 5% supplement) in GrowSafe bunks. During the post-weaning evaluation (initiated on day 1), heifer (168 ± 23 kg and 156 ± 7 days of age) DMI was collected for 56 days and body weights (BW) were collected every 14 days. Following the intake evaluation, heifers rotated daily for 166 days though 33 paddocks of 2.4 ± 0.5 hectares each and were weighed every 28 days. Data were analyzed using the MIXED procedure of SAS 9.4. As designed, birth body weight differed (P &amp;lt; 0.01) between classifications (27, 32, and 37 kg for LtBBW, AveBBW, and HvyBBW, respectively). Heifers classified as LtBBW were born earlier (P = 0.02) than AvgBBW and HvyBBW. Heifer BBW classification affected (P &amp;lt; 0.01) weaning weights; heifers classified as LtBBW and AvgBBW had lighter weaning weights than HvyBBW heifers. Birth weight category affected (P &amp;lt; 0.01) BW on days 1, 28, and 56. On day 1, heifers classified as LtBBW were the lightest, AvgBBW were intermediate, and HvyBBW were the heaviest; however, on days 28 and 56, heifers classified as LtBBW were lighter than AvgBBW and HvyBBW. Heifers classified as LtBBW and AvgBBW had less (P &amp;lt; 0.01) DMI and average daily gain (ADG) than HvyBBW during the post-weaning evaluation period. Gain to feed during post-weaning evaluation period was not affected (P = 0.94) by heifer BBW classification. Birth weight category affected (P &amp;lt; 0.01) BW during the grazing season on days 28, 56, 84, 113, 141, 168, 196, and 223. On days 84, 96, and 223, heifers classified as LtBBW were lighter than AvgBBW and HvyBBW; however, on days 113, 141, and 168, LtBBW were lightest, AvgBBW were intermediate, and HvyBBW were the heaviest. During the grazing period, ADG did not differ (P = 0.72) between BBW classifications. In conclusion heavy birth weight heifers had greater post-weaning DMI and ADG when fed a high grain diet; however, grazing ADG did not differ. Heavy birth weight heifers were heavier throughout the duration of the experiment.

Effects of corn processing index and forage source on performance, blood parameters, and ruminal fermentation of dairy calves

The objective of this study was to investigate the effects of corn processing index (CPI)—particularly at 70% and 85%—in starter feed in combination with the provision of forage, either alfalfa hay (AH) or wheat straw (WS), on feed intake, growth performance, rumen pH, and blood metabolites of dairy calves. Forty-eight male Holstein calves (43.0 ± 1.5 kg body weight) were randomly assigned (n = 12 calves per treatment) to one of four dietary treatments: (1) a textured starter diet containing 70% CPI and AH (70CPIAH), (2) a textured starter feed containing 70% CPI combined with WS (70CPIWS), (3) a textured starter feed containing 85% CPI and AH (85CPIAH), (4) a textured starter feed containing 85% CPI combined with WS (85CPIWS). Intake of starter feed (TMR) and milk was individually monitored and recorded daily, while body weight was measured weekly. On days 30 and 65, blood samples were collected from all calves 3 h after morning feeding. No interaction was detected between the CPI of starter feed diets and forage provision for starter intake, dry matter intake (DMI), metabolizable energy intake (MEI), feed efficiency (FE), average daily gain (ADG), and body weight (BW). The preweaning and overall DMI, preweaning, postweaning and overall FE and ADG, preweaning and overall starter intake, preweaning and overall ME intake, and postweaning and overall BW were greater for calves fed 85CPI than those fed 70CPI starter diets. Postweaning and overall ADG and postweaning FE were greater in calves fed WS than those fed AH. Body length and hip width were greater for calves offered 85CPI than in fed 70CPI. Wheat straw supplementation increased rumen pH at day 65 in calves fed 70CPI, but not in those fed 85CPI. No interaction was found between the CPI in the starter feed diet and the forage source for starter intake and DMI, MEI, FE, and BW. The results showed that including corn with 85% processing index in dairy calf starters improved their growth performance.

Effect of weaning system on lamb growth, mammary gland development and ewe milk production in dairy sheep managed in an outdoor pasture-based commercial farming system

The objective was to merge science and practice to determine the feasibility of a mixed suckling and milking system compared with a traditional exclusive suckling management system on the production performance of dairy sheep and their progeny in an outdoor pasture-based farming system at commercial scale. At 14 d postpartum, twin- and triplet-bearing mixed-age East Friesian ewes were randomly allocated to either a mixed system of once-a-day milking,suckling and early weaning (MS, n=61) or control with exclusive suckling and later weaning (Ctrl, n=57) using a randomised block design. MS lambs had lower live weight at weaning (14.6 vs. 16.7 kg; P&lt;0.001) but 3-5weeks post-weaning average daily gain and mammary gland mass was similar between groups. Ewe lamb mammary mass was positively associated with post-weaning but not pre-weaning live weight gain (P&lt;0.01). Weaning system influenced the percentage of protein, total solids and fat (MS &gt; Ctrl) while milk yield, somatic cell count and lactose levels were not different. This study highlighted that the MS comparedwith Ctrl system had no negative effects on dam or progeny performance.

On-farm performance evaluation of Maale goats under agro-pastoral management in Southwest Ethiopia

This study was conducted in Maale district Southwest Ethiopia with the objective of evaluating the productive and reproductive performance of Maale goats under agro-pastoral management conditions. Thirty households that have flocks numbers of more than ten were purposely selected and monitored from July 2018 to July 2019. Growth data of birth weight, three month, six month, nine month and yearly weight; birth type and parity were collected. The data were analyzed using the General Linear Model (GLM) procedure of SPSS (21). The overall mean birth weight of the kids was 2.57±0.05 kg (males 2.68±0.07 and females 2.47±0.07 kg). The weaning and six months weight of kids was significantly different (p&lt;0.05) between sexes of kids with 7.66±0.25 and 6.90±0.23 kg for male and female kids, respectively. The average body weight of males and females for six months; nine months and yearly were 11.57±0.30, 10.42±0.28; 15.42±0.27, 14.69±0.25 and 19.03±0.28, 18.43±0.25 kg, respectively. The birth type showed a significant (p&lt;0.05) difference in birth weight. The result further indicated that the weaning weight of single and twin kids was highly significant (p&lt; 0.001) and recorded as 7.66±0.25 and 6.90±0.23 kg, respectively. The overall pre-weaning average daily gain was 51.64±1.89 g day-1 (54.47±2.81 male and 48.93±2.53 g day-1 female). The birth type was significantly (p=0.01) different in pre-weaning growth rate and recorded 57.24±1.63 and 45.24±3.59 g day-1 for single and twin kids, respectively. Twins had higher post-weaning average daily gain than single and recorded as 43.61±1.48 and 40.76 ±0.70 g day-1, respectively. It was concluded that, along with other management interventions, the reproduction and growth performance of Maale goats is reasonably good and suited for community-based breeding strategies and higher performance could be expected. Int. J. Agril. Res. Innov. Tech. 12(2): 7-13, December 2022

Growth performance, antibody response, and mammary gland development in New Zealand dairy replacement bovine heifers fed low or high amounts of unpasteurized whole milk.

This study evaluated the influence of feeding low and high preweaning allowances of unpasteurized whole milk (MA) on intake, selected blood metabolites, antibody response, mammary gland growth, and growth of New Zealand (NZ) dairy heifers to 7 mo of age. At 10 ± 2 d of age (study day 0), group-housed (six·pen-1) heifer calves (Holstein-Friesian × Jersey) were allocated to low (4 L whole milk·calf-1·d-1; n = 7 pens) or high (8 L whole milk·calf-1·d-1; n = 7 pens) MA for the next 63 d. Calves were gradually weaned between days 63 ± 2 and 73 ± 2. Calves in each pen had ad-libitum access to clean water, pelleted calf starter, and chopped grass hay from day 1 to 91 ± 2 d. At 92 ± 2 d, all calves were transferred to pasture, grazed in a mob, and their growth and selected blood metabolites were measured until day 209. All animals were weighed weekly during the indoor period (to day 91) and then at days 105, 112, 128, 162, 184, and 209. Skeletal growth measurements and blood samples to analyze selected metabolites were collected at the start of the experiment, weaning, and then postweaning on day 91, and day 201. Specific antibodies against Leptospira and Clostridia were quantified in weeks 7, 13, and 27. Mammary glands were scanned using ultrasonography at the start of the experiment, weaning, and day 201. Feeding high vs. low amounts of MA increased the preweaning growth in heifer calves (P = 0.02) without negatively affecting postweaning average daily gain (ADG) (P = 0.74). Compared with heifers fed with low MA, high MA fed heifers had a greater increase in antibodies against Leptospira and Clostridia by 13 wk of age (P = 0.0007 and P = 0.06, respectively). By 27 wk of age, the antibody response was the same in heifers offered low or high MA. There was no effect of MA on the total size of the mammary gland, measured by ultrasonography, at weaning and 7 mo of age. However, the greater MA was associated with more mammary parenchyma (P = 0.01) and less mammary fat pad (P = 0.03) in back glands at 7 mo of age compared with heifers fed lower MA. In conclusion, feeding a high vs. a low amount of unpasteurized whole milk increased the preweaning growth of New Zealand replacement heifers without negatively affecting their ADG during postweaning under grazing conditions. Feeding more (8 vs. 4 L·d-1) unpasteurized whole milk positively affected antibody responses early in life and mammary gland composition by 7 mo of age in dairy heifers reared for pasture-based dairy systems.

Genetic Evaluation of Post Weaning Growth Performances in Large White Yorkshire Cross Bred Pigs

Background: The profitability in swine production is mostly associated to the superior growth performance. The information pertaining to the genetic and non-genetic factors influencing growth traits is significant to enable animal breeders to adopt better selection and managemental methods. Methods: Data from 50% LWY-Desi genetic group and 75% LWY-Desi genetic group that were maintained at the All India Coordinated Research Project (AICRP) on Pigs, Sri Venkateswara Veterinary University, Tirupati were used to understand the effect of genetic and non-genetic parameters on production traits. Result: The genetic group, period of birth, season, parity and sex have significant influence on post weaning body weights in most of the ages. Certain age groups showed significant effect on post-weaning average daily gain; but no specific trend was observed for age groups between the two genetic groups. The heritability estimates for post weaning body weights and ADG were medium to high in both the genetic groups. The genetic and phenotypic correlations among post-weaning body weight were inconsistent in direction. Overall, the 75% LWY-Desi genetic group performed better than 50% LWY-Desi genetic group, presumably due to the higher exotic inheritance and genetic superiority.

English

The objectives of this study were to identify the environmental factors that influenced growth traits and to evaluate phenotypic response of growth traits to selection at weaning (S1) and 18 months of age (S2) in Tswana cattle. Phenotypic analysis for average daily gains (ADGs) and growth traits were conducted using 7226 records of animals, which were born between 1995 and 2013 from 1662 dams and 188 sires in 54 contemporary groups, using mixed models. Growth traits analysed were birth weight (BWT), weaning weight (WWT), yearling weight (YWT) and 18-month weight (EWT). The analysed ADGs were pre-weaning average daily gain (ADG1) and post-weaning average daily gain (ADG2). The identified significant environmental effects for growth traits and ADGs were sex of the animal, dam age, selection line and contemporary group. S1 resulted in increased BWT, WWT, YWT, EWT and ADGs compared with S2. Animals from both S1 and S2 exhibited higher weights and ADGs than those in the unselected control line (S3). The significant environmental factors should be accounted for whenever genetic evaluation for growth performance of Tswana cattle breed is carried out. Mass selection for weaning weight can yield optimal improvement on growth performance of Tswana cattle when properly carried out. Key words: Environmental factors, growth performance, growth traits, cattle, selection.

Early growth, backfat thickness and body condition has major effect on early heifer pregnancy in Nellore cattle.

The aim was to evaluate the association between growth, carcass and visual scores traits with precocious calving in Nellore cattle. Birth weight (BW), weight at 120, 210, 365 and 450 days of age, pre and post-weaning average daily gain, rib eye area, backfat thickness (BF), rump fat thickness and visual scores obtained at 18 months were used for the analysis. Records from 700 females born between 2009 and 2015, exposed to mating starting at 11 months of age were analyzed. Discriminant analyzes were performed with the software Statistica. BW and BF showed the highest (P>0.01) discrimination value for early heifer pregnancy (EP). Extreme intrauterine growth retardation can result in slower growth, which reflects in the worst reproductive performance, confirmed by the variation in BW between precocious and conventional heifers. The results also demonstrate that the level of body fat affects begin of puberty. Bone structure, musculature, depth, tail insertion and rump scores presented the highest discrimination value for EP. These traits can be used as selection tools to improve sexual precocity in female Nellore cattle. The results obtained in this study would support farmers to guide the heifer management and decisions in order to enhance the EP.

Polymorphisms in hormone-sensitive lipase and leptin receptor genes and their association with growth traits in Barki lambs.

Background and Aim:Marker-assisted selection has many advantages over conventional selection in animal breeding. The candidate gene approach has been applied to identify genetic markers associated with economically important traits in livestock. This study was established to investigate variation in the hormone-sensitive lipase (HSL) and leptin receptor (LEPR) genes, and their association with growth traits in Barki lambs.Materials and Methods:Records for birth weight (BW), pre-weaning average daily gain (ADG1), weaning weight (WW), post-weaning average daily gain (ADG2), and marketing weight (MW) were obtained from 247 Barki lambs. Polymerase chain reaction–single-stranded conformational polymorphism analyses were used to detect variation in exon 9 of HSL and exon 19 of LEPR. General linear models were used to test for associations between the variation in ovine HSL and LEPR, and growth traits.Results:The SSCP banding patterns for HSL showed three variants (H1, H2, and H3), which contained two nucleotide-sequence differences (c.1865C>T and c.2038T>C). Two SSCP banding patterns (L1 and L2) were observed for LEPR and these contained two nucleotide-sequence differences (c.2800G>A and c.2978C>G). The HSL genotype showed no effect on the studied traits. The LEPR genotype was proven to have significant effects (p<0.05) on ADG2 and MW. The presence of the L1 variant was associated (p<0.01) with decreased ADG2 and MW.Conclusion:The finding of an association between LEPR gene variation and growth rate after weaning in Barki lambs warrants efforts to improve this trait.

Nucleotide Supplementation to Whole Milk Has Beneficial Effects on Post-Weaning Holstein Calf Performance.

Simple SummaryThe positive effects of nucleotide (NU) supplementation in milk replacer have been elucidated in infants and partly in dairy calves; however, NU addition to whole milk has not been evaluated yet. In this study, a NU-containing supplement was added to whole milk at rate of 0.5 and 1 g/d. Without any effects on pre-weaning performance, post-weaning intake was improved as NU increased and final body weight was greater in NU supplemented calves. Nucleotide supplementation to whole milk linearly decreased days with loose feces in the first month of life. These results show that NU has beneficial effect on calf health status and intake even if it is supplemented to whole milk.The positive effects of nucleotide (NU) supplementation in milk replacer have been elucidated in infants and in dairy calves; however, NU addition to whole milk has not been evaluated previously. This study aimed to assess NU supplementation in the whole milk on calf growth and health. Thirty Holstein calves (body weight: 39.1 ± 1.0 kg; 3 d after birth) were randomly assigned to the following treatments: whole milk without any supplementation (NU0), whole milk + 0.5 g/d added a NU-containing supplement to whole milk (NUCS0.5), and whole milk + 1 g/d added a NU-containing supplement to whole milk (NUCS1). Calves were weaned at d 55 and stayed on study until d 75. Calves had free access to feed and water throughout the study. Dry matter intakes (DMI) were similar among treatments (p > 0.05) during the pre-weaning period; however, increasing NU resulted in a linear (p < 0.05) increase in DMI during the post weaning period (2158, 2432, and 2518 g/d for NU0, NUCS0.5, and NUCS1, respectively). Treatments did not affect body weight (BW) at the first and second month of study, but final BW linearly increased as NU was added (87.1, 90.6, and 95.4 kg for NU0, NUCS0.5, and NUCS1, respectively). Neither pre-weaning average daily gain nor post-weaning average daily gain was affected by treatments; accordingly, feed efficiency was similar among treatment groups. Days with loose fecal score were linearly decreased as NU was added to whole milk during the first month of life, while the fecal score did not differ among treatments until the end of the study. No difference was observed in the skeletal growth of calves in the current study. Therefore, it can be concluded that NU supplementation in the whole milk has some beneficial effects on calf performance in terms of final BW, post-weaning DMI, and less days with loose feces.

Effect of housing improvement and other factors on the growth of heifer calves on Kenyan smallholder dairy farms.

This trial evaluated average daily gain (ADG) effects of heifer calves (< 1year old) from affordable housing improvements to the roof and flooring on 150 randomly allocated smallholder dairy farms. During the 16-month data collection period, bimonthly farm visits were used to measure weight and other animal- and farm-level factors on the 187 study calves. Multivariable linear regression was used to model ln ADG and ADG during pre-weaning and post-weaning periods, respectively. Median pre-weaning and post-weaning ADGs were 0.307 (interquartile range (IQR): 0.227-0.398) and 0.487 (IQR: 0.354-0.675) kg/d, respectively. In the final pre-weaning model (p<0.050), factors positively associated with ln ADG were calf age at first acaricide application, and total number of calf pens, while factors negatively associated with ln ADG included calf mortality risk over the last 5years and calf age at first ad lib access to water. In an interaction term, for calves from parity 3+ dams, ADG was lower when milk was fed twice/day than thrice/day, with no difference in calves of lower parity dams. In the final post-weaning model, housing improvements increased ADG by 5.6%. Other factors positively associated with post-weaning ADG were feeding of calf pellets, wheat bran, maize bran, and hay. Calf age at first introduction of concentrate and calf mortality risk over the last 5years were negatively associated with ADG. In an interaction term, ADG was high when there were faecal coccidia oocysts and when calves had visual or physical contact with their dams, but low when faecal coccidia cysts were present, and these dam-calf connections were absent. In a second interaction term, ADG increased with more calf pens for female principal farmers, while remaining low for male principal farmers. In conclusion, while controlling for other factors of ADG, making affordable calf housing improvements enhanced ADG, particularly during the post-weaning period.

Analysis of X chromosome and autosomal genetic effects on growth and efficiency-related traits in sheep

Abstract Context It is believed that the X chromosome plays an important role in influencing quantitative traits. Despite this, until recently, X-linked genetic effects have not been considered in models to estimate genetic parameters for economically important traits of livestock. Aims A large dataset was analysed to quantify autosomal additive genetic, X-linked additive genetic and maternal effects on growth and efficiency-related traits in Baluchi sheep. Methods Traits included bodyweight at birth, weaning (WW), 6 months (W6), 9 months and yearling age, pre- and post-weaning average daily gain, pre- and post-weaning Kleiber ratio, pre- and post-weaning efficiency of growth (EFb), and pre- and post-weaning relative growth rate. Each trait was analysed using the REML procedure fitting a series of eight univariate animal models. For each trait, the most appropriate model was selected by the Akaike information criterion and Bayesian information criterion. Key results The X-linked genetic effect was significant only in models fitted to EFb, where the estimate of X-linked heritability was 0.02 ± 0.01 from the best model. Other traits were not affected significantly by X-linked genetic effects. Estimates of autosomal heritability () for growth traits were between 0.06 ± 0.02 (post-weaning average daily gain, pre-weaning relative growth rate) and 0.22 ± 0.04 (bodyweight at yearling age), and ranged between 0.02 ± 0.01 (EFb) and 0.08 ± 0.02 (pre-weaning Kleiber ratio) for efficiency-related traits. Maternal effects significantly contributed to phenotypic variation of most traits, with larger effects on traits measured early in life. For EFb, the Spearman’s correlation between breeding values including and excluding X-linked effects was 0.95. It was 1.00 for traits that were not affected by X-linked genetic effects. Conclusions Although the proportion of phenotypic variance attributed to X-linked loci for most traits was zero, the importance of X-linked genetic effects should be at least tested in models when estimating variance components for growth and efficiency traits of Baluchi sheep. Implications As estimates of genetic parameters are breed-specific, we recommend for growth and efficiency traits of sheep that the importance of X-linked genetic effects should be evaluated to assess if these effects should be included in models used in genetic evaluation.

Feeding Tall Fescue Seed during Mid and Late Gestation Influences Subsequent Postnatal Growth, Puberty, and Carcass Quality of Offspring.

Simple SummaryLittle is known about the exposure to ergot alkaloids, a class of mycotoxins, during fetal development on subsequent post-weaning growth, puberty, and carcass quality of the offspring. This study evaluated post-weaning growth, puberty attainment, and carcass quality in lambs that were exposed to endophyte-infected or endophyte-free tall fescue seed during different stages of gestation. Puberty was delayed in ewe lambs that were exposed to ergot alkaloids during late gestation. Ergot alkaloid exposure had minor effects on growth and carcass traits in wether lambs fed high concentrates but alterations in fat deposition and tenderness were observed. These results indicate that exposure to ergot alkaloids during gestation does alter subsequent post-weaning puberty attainment and body composition of the offspring.Weaned lambs (n = 82), born to ewes fed endophyte-free (E−) or endophyte-infected (E+; 1.77 mg hd−1 d−1 ergovaline + ergovalinine) tall fescue seed from d 35 to 85 of gestation (MID) and/or d 86 of gestation to parturition (LATE), were used to examine how ergot alkaloid exposure during fetal development altered subsequent puberty attainment or carcass quality. Lambs were weaned at 75 d of age and separated by sex to assess puberty in ewe lambs (n = 39) and to evaluate growth, carcass and meat quality in wethers (n = 43). Data were analyzed with maternal fescue treatment, stage of gestation, and two-way interaction in the model. Age at puberty tended (P = 0.06) to be longer for ewe lambs born to dams fed E+ fescue during LATE gestation versus those fed E−. Post-weaning average daily gain tended to be higher (P = 0.07) for wether lambs born to dams fed E+ fescue seed during MID gestation compared to E−. Exposure to ergot alkaloids during fetal growth altered (P < 0.10) longissimus muscle weight and color, lipid deposition, fatty acid composition, and shear force values of semimembranosus muscle in wether lambs. These results indicate that exposure to ergot alkaloids in utero does alter subsequent post-weaning puberty attainment and body composition in offspring.

Potential interactive effects between corn grain forms (ground vs. whole) of starter feed and forage provision: Effects on growth and health status of intensified milk-fed Holstein calves

Increasing starter intake has been correlated with greater average daily gain (ADG) and less digestive problems in pre-weaning calves. Forage inclusion in mash starter feed as well as the whole (compared to the ground) grain provision in the starter feed are among the studied ways to increase starter intake. Forty-four Holstein female calves (body weight = 39.67 ± 5.9 kg) were randomly assigned to 1 of 4 the dietary treatments in a completely randomized design with a 2 × 2 factorial arrangement of treatments. Treatments were: (1) mash starter feed containing ground corn grain and without forage provision (WS0-GC); (2) mash starter feed containing whole corn grain and without forage provision (WS0-WC); (3) mash starter feed containing ground corn grain with 100 g/kg forage provision (WS10-GC); and (4) mash starter feed containing whole corn grain and with 100 g/kg forage provision (WS10-WC). The calves were housed in individual pens bedded with clean wheat straw. Calves were weaned at 60 d of age and stayed on study until d 75. The dry matter intake (DMI) as well as starter intake were different among treatments within the pre-weaning period; significant interaction between forage and corn grain physical form indicated that WS10-GC group had the greatest DMI and starter intake (P = 0.05), but this greater intake did not result in greater ADG for those calves. Regardless of forage, whole corn grain inclusion resulted in less starter intake during post-weaning period. Neither pre-weaning nor post-weaning ADG was affected by treatments. Without any effect on pre-weaning gain:feed ratio, forage provision led to the least gain:feed (P = 0.04) but whole corn grain inclusion tended to improve gain:feed (P = 0.10) during post-weaning. Pre- and post-weaning blood total protein concentrations were greater in whole corn grain fed calves (P < 0.01), but feeding forage resulted in greater blood beta-hydroxybutyrate (BHB) during post-weaning period; whole corn grain interaction with forage inclusion led to lesser BHB in WS10-WC than in WS10-GC group (P < 0.05). No differences were observed for rumen fluid parameters and health status among treatments, except a tendency for greatest rumen propionate and butyrate in forage fed calves compared to others at d 45 (P = 0.06). Present results indicated that, with an intensive plan of milk feeding, whole or ground corn had no effect on growth performance and blood metabolites and the forage provision only resulted in greater starter intake but not greater ADG.

Rederivation by Cryopreservation of a Paternal Line of Rabbits Suggests Exhaustion of Selection for Post-Weaning Daily Weight Gain after 37 Generations.

Simple SummaryThis study was conducted to evaluate the effect of a long-term selection for post-weaning daily weight gain after 37 generations, using vitrified embryos with 18 generational intervals to rederive two coetaneous populations, reducing or avoiding genetic drift, environmental and cryopreservation effects. This study reports that the selection programme had improved average daily weight gain without variations in adult body weight but, after 37 generations of selection, this trait seems exhausted.Rabbit selection programmes have mainly been evaluated using unselected or divergently selected populations, or populations rederived from cryopreserved embryos after a reduced number of generations. Nevertheless, unselected and divergent populations do not avoid genetic drift, while rederived animals seem to influence phenotypic traits such as birth and adult weights or prolificacy. The study aimed to evaluate the effect of a long-term selection for post-weaning average daily weight gain (ADG) over 37 generations with two rederived populations. Specifically, two coetaneous populations were derived from vitrified embryos with 18 generational intervals (R19 and R37), reducing or avoiding genetic drift and environmental and cryopreservation effects. After two generations of both rederived populations (R21 vs. R39 generations), all evaluated traits showed some progress as a result of the selection, the response being 0.113 g/day by generation. This response does not seem to affect the estimated Gompertz growth curve parameters in terms of the day, the weight at the inflexion point or the adult weight. Moreover, a sexual dimorphism favouring females was observed in this paternal line. Results demonstrated that the selection programme had improved ADG without variations in adult body weight but, after 37 generations of selection, this trait seems exhausted. Given the reduction in the cumulative reproductive performance and as a consequence in the selection pressure, or possibly/perhaps due to an unexpected effect, rederivation could be the cause of this weak selection response observed from generation 18 onwards.

Effects of conditioner retention time during pelleting of starter feed on nutrient digestibility, ruminal fermentation, blood metabolites, and performance of Holstein female dairy calves

This study evaluated the effects of conditioner retention time during the pelleting process of starter feed on intake, nutrient digestibility, ruminal fermentation, blood metabolites, and growth performance of dairy calves. A total of 30 Holstein female dairy calves [40 ± 1.93 kg of body weight (BW)] were randomly assigned to 1 of 3 treatments: (1) pelleted starter conditioned for 0 min (CON), (2) pelleted starter conditioned for 2 min, and (3) pelleted starter conditioned for 4 min. Three pelleted starter feeds had similar nutritional composition, and the starters were blended with 3% chopped wheat straw and fed to individually housed calves from d 3 to 70 of age. All calves were fed 4 L/d of pasteurized whole milk twice daily at 0800 and 1600 h from d 3 to 50 of calf age, followed by 2 L/d of morning feeding from 51 to 56 d of age. All calves were weaned on d 56 of age and remained in the study until d 70 of age. With the increase of conditioner retention time during pellet processing for 0, 2, and 4 min, the gelatinized starch content of pelleted starter feed linearly increased from 14, 30, and 45%, respectively. Additionally, the pellet durability and hardness also linearly increased with increasing conditioner retention time during pelleting. Feeding pelleted feed prepared using different conditioner retention time did not affect feed dry matter intake, metabolizable energy intake, weaning BW, final BW, or feed efficiency during the study. We observed no differences in the total-tract apparent digestibility of organic matter, neutral detergent fiber, and crude protein around weaning (d 49 to 56 of age) and after weaning (d 63 to 70 of calf cage); however, the digestibility of dry matter and starch after weaning was increased with increasing conditioner retention time during pelleting of starter feed. No difference was found in overall average daily gain (ADG) or growth rates of hip height, withers height, and heart girth. Ruminal volatile fatty acid profile was not affected by pelleting under different conditioner retention times. The ruminal ammonia concentration tended to be lower for calves fed the 4-min diet compared with those fed the CON diet during the postweaning period. The postweaning (d 57-70 of age) ADG was greater for calves fed the 4-min diet compared with those fed the CON diet. In conclusion, the conditioning time during the pelleting process of starter feed increased the gelatinization of starch, durability, and hardness of the pellets but did not influence feed intake, feed efficiency, and skeletal growth during the first 70 d of age. Increasing conditioning time during the pelleting process improved postweaning ADG; however, the final BW of calves was similar among treatments.