Journal of Livestock Science and Technology
Volume:9 Issue: 2, Dec 2021

The objective of this study was to investigate the effects of dietary zinc (Zn) sources and levels supplementation on performance, egg quality, blood parameters, and egg yolk Zn content in laying hens from 28 to 36 weeks of age. Two hundred laying hens (Hy-Line W-36) were weighed individually and placed randomly in cages with five treatments, five replicates of 8 birds in each by 2×2+1 factorial arrangement. Treatments consisted of a control diet (corn-soybean meal as a basal diet without Zn supplementation) and the diet supplemented with 80 and 120 mg of Zn/kg, added as either Zinc-sulfate (ZnSulf) or Zn-methionine (ZnMet), respectively. No significant differences were observed for treatments on laying hen performance from 28 to 36 weeks of age. Eggshell thickness significantly improved (P<0.001) by ZnMet in comparison to ZnSulf. Eggshell thickness significantly improved by increasing Zn from 80 to 120 mg/kg of the diet (P<0.05). Plasma HDL (P<0.001), alkaline phosphatase activity (P<0.05), total protein, and albumin concentrations (P<0.001) were significantly increased by ZnMet in comparison to ZnSulf supplementation. Plasma Fe, Cu, Zn, P and Zn content of the egg yolk were not affected by Zn sources or levels. Plasma Ca was higher in hens receiving 120 mg/kg ZnMet/kg than other treatments (P<0.01). In conclusion, more positive effects on eggshell quality and some blood parameters were found by dietary ZnMet supplementation at 80 or 120 mg/kg diet than ZnSulf in laying hens under the conditions of this study.

The aim of the present study was to investigate the effects of different sources of non-fibrous carbohydrates (NFC) in the dairy cow diet supplemented with small peptides of cottonseed (Fortide C) on in vitro ruminal gas production (GP), fermentation parameters, substrate disappearance and microbial enzyme activity. Four experimental diets were fed, which were iso-caloric and iso-nitrogenous, containing 1) maize, 2) barley, 3) wheat or 4) a maize+barley mixture as the main sources of NFC. Each experimental diet was supplemented with 7.05 g Fortide C/kg dry matter (DM) and incubated with media containing rumen liquor for 96 h in vitro. Dietary supplementation of the Fortice C-contained diet with wheat grain yielded greater gas production (GP) at 16 h of incubation, total GP and potential GP (b) than those containing maize (P<0.05), but similar to barley-containing diet (P>0.05). Other GP parameters including GP at 24, 48 and 72 h of incubation and constant rate of GP (c) were similar among the experimental diets. The highest and lowest DM disappearance, apparently degraded substrates, organic matter disappearance, estimated metabolizable energy, short chain fatty acids and microbial protein synthesis (MPS) were observed with the using wheat and maize in the diets supplemented with Fortide C, respectively (P<0.05). Using wheat in the diet decreased NH3-N compared to the maize diet (P<0.05). The inclusion of the wheat in the diet supplemented with Fortide C increased activity of carboxymethyl cellulase and α-amylase compared to the maize diet (P<0.05), while it was similar to the barley diet (P>0.05). However, microcrystalline cellulase and filter paper-degrading activities were unchanged among the dietary treatments. Overall, using wheat as the main source of NFC in the dairy cow diet supplemented with Fortide C improved in vitro ruminal fermentation profile, substrate disappearance, MPS and microbial enzyme activity compared to maize or maize+barley-based diets.

Follicle-stimulating hormone (FSH) is necessary for the hypothalamic-pituitary-gonadal axis, and plays an important role in reproduction by binding to a specific receptor (FSHR) through β-subunit of FSH in the surface of the ovarian granulosa cells. This study aimed to characterize FSH β-subunit gene (FSHβ) polymorphism and its association with litter size (LS) using a sample of 118 Mehraban sheep. Polymerase chain reaction (PCR) was performed to amplify two fragments of 300 bp and 431 bp of the ovine FSHβ gene (Oar_v4.0; Chr 15, NC_019472.2). Polymorphisms in the studied fragments were then explored using single strand conformational polymorphism (SSCP) and DNA sequencing methods. A total of seven single-nucleotide polymorphisms (SNPs), including g.59078564 C>G, g.59078624 T>C, g.59078655 T>C, g.59078691 T>C, g.59078754 C>A, g.59080186 G>C and g.59080365 C>T, were found among the six detected SSCP patterns A to F. Moreover, two novel indel polymorphisms called e.g., g.59078702del8-bp−ins64-bp and g.59078726ins54-bp were identified among the three different SSCP genotypes patterns G to I. We found significant differences on prolificacy categories between SSCP genotypes patterns D, E and F (P < 0.01) that simultaneously represented SNP polymorphisms of g.59078754 C>A, g.59080186 G>C and g.59080365 C>T. Similarly, novel indel polymorphisms revealed a significant difference on prolificacy categories between SSCP genotypes patterns G, H and I (P < 0.05). Our results suggest that the FSHβ is a strong candidate gene to associate with the LS in sheep.

Runs of homozygosity (ROH) stretches are continuous homozygous fragments of the genome, which are more suitable for calculating genomic inbreeding, identifying footprints involved in economic traits and understanding population history in livestock species. In this study, using a dataset of Ovine SNP50 BeadChip genotypes, the distribution of ROH across the nine different sheep populations (Soay n= 110, Australian Poll Dorset n=108, Australian Suffolk, n=109, Finn sheep, n= 99 , Scottish Texel, n= 80 , Scottish Blackface, n= 56 , Galway, n= 49 , Border Leicester, n= 48 , German Texel, n=46) from Europe were investigated. ROHs were detected by used PLINK v1.09 with the minimal number of SNPs in ROH was set to 40; the maximal gap between the adjacent SNPs was set1 to Mb; the minimum SNP density per ROH was set to 1/100 kb and no heterozygote allowed less than 16 Mb. The detected ROHs were specified based on length to four categories: 1–4 Mb, 4–8 Mb, 8–16 Mb and above 16 Mb. A total of 22,204 ROHs were identified, in which ~ 92 – 98 % of them were less than 16 Mb in length, which covered 4.6% to 12.9% of the entire genome. The inbreeding coefficient based on ROH (FROH) varied among populations (ranging from 0.05 to 0.14). The highest inbreeding rate was found in Border Leicester and Soay breeds. In addition, we detected 90 possible ROH Islands that were overlapped with candidate genes associated with different economic traits such as; body weight, meat production, fat deposition, horn-less, and coat color in sheep. Our results suggest that although genetic selection for meat and wool traits in these breeds have been extensively carried out for the last decades, the autozygotic proportion of their genome is still considerably low, and it could lead an acceptable response to selection in breeding schemes.

The objective of this study was to estimate genetic, phenotypic and residual correlations between ewe reproductive and lamb weight traits in D’man sheep. Data used in this study were 1804 reproductive and weight records collected between 1988 and 2015 from 530 replacement females, born from 82 sires and 298 dams. The ewe reproductive traits included litter size and litter weight at birth (LSB and LWB) and at 90 days (LSW and LWW) per ewe lambing and mating weight (MW), while the lamb weight traits investigated were weights at birth (BW), 90 (WW) and 135 (W135) days. Covariance components between the reproductive traits on the one hand and the weight traits on the other hand were estimated using bivariate analyses by employing the animal model that was deemed to be most appropriate from the univariate analyses for each trait. The genetic correlations between litter traits and body weights were low and in general not significantly different from zero ranging from -0.12 to 0.11, whereas those between ewe MW and lamb weights were positive and moderate varying from 0.16 to 0.51. The corresponding phenotypic correlations were slightly lower and varied from -0.04 between LSW and WW to 0.12 between LWW and BW and between LSW and W135. The residual correlations were in general similar to genetic correlations, except those between MW and body weights that were lower. It was concluded that selection for a genetic improvement in either of reproductive and weight traits would have little effect on genetic response in the other trait.

The aim of this study was to investigate the calpastatin gene expression in different tissues of Kermani sheep using the real-time PCR. Tissue samples from the brain, humeral muscle, femoral muscle, liver, adipose tissue, rumen and testis were taken from 30 Kermani sheep. Total RNA was extracted using RNXTM plus solution. To determine the quantity (concentration) and quality of the extracted RNA, two methods of RNA; electrophoresis on 1% agarose gel and a Nano drop device were used. A Thermoscientific kit (Iran) was used for cDNA synthesis. After performing normal PCR reactions and obtaining the desired binding conditions and temperature for the genes, real-time PCR was performed to study the relative gene expression. The Beta-actin gene was used as a housekeeping gene. The Pfaffl method was used to analyze the data. The quality of the extracted RNAs was good. The presence of two 18S and 28S bands in the rRNA indicated that the RNA was healthy and the absence of an additional band was an indication of its purity. For the calpastatin gene, the 189bp fragment, and for Beta-actin, the 206bp fragment was observed in all tissues. The real-time PCR findings showed that calpastatin gene was expressed in all tissues (brain, humeral muscle, liver, adipose, femoral tissue, rumen and testis) with the highest level of expression in the humeral and femoral muscles and the lowest level in adipose tissues. This study lays a foundation for further calpastatin research in sheep. It is suggested that this study be conducted on a greater number of animals, and different breeds, sexes, ages and physiological stages to reach a more comprehensive conclusion.

The aim of the present study was to investigate the advantages of structural equation modeling for genetic evaluation of body weight traits in Moghani sheep, using data collected on 6,320 Moghani lambs during a 23-year period (1988 to 2011) in Jafarabad Breeding Station of Moghani Sheep. Traits investigated were the body weight at birth (BW), weaning (WW), six-month (6MW), nine-month (9MW) and yearling weight (YW). Three multivariate animal models including the standard (SMM), fully recursive (FRM) and temporal recursive (TRM) models were compared in terms of deviance information criterion (DIC) and predictive ability measures including mean square of error (MSE) and Pearson's correlation coefficient between the observed and predicted values (r(y, )) of records. Spearman's rank correlation coefficients between posterior means of direct genetic effects for the studied traits were also calculated across all, 50% top-ranked, 10% top-ranked and 1% top-ranked animals. In general, TRM performed better than SMM and FRM in terms of DIC, MSE and r(y, ): resulting in the lowest DIC and MSE and the highest r(y, ). All structural coefficients estimated by TRM were statistically significant. Comparisons of Spearman's rank correlations between posterior means of direct genetic effects of lambs for the studied body weight traits under SMM and TRM showed that considering the causal relationships among the studied growth traits resulted in considerable re-ranking of the animals based on the estimated breeding values, especially for the top-ranked animals; implying that TRM had more plausibility over SMM for genetic evaluation of these traits in Moghani sheep.

Six univariate animal models, including various combinations of the maternal effects, were used to estimate the (co)variance components and genetic parameters for growth rates from birth to weaning (GR1), weaning to six months of age (GR2) and weaning to 12 months of age (GR3), and the corresponding Kleiber ratios (KR1, KR2, KR3), efficiencies of growth (EF1, EF2, EF3) and relative growth rates (RGR1, RGR2, RGR3) in Iran-Black sheep. The most appropriate model for each trait was identified by the Akaike Information Criterion (AIC). In addition, bivariate analyses were used to estimate the (co)variance components between traits. Estimated values of the direct heritability (±S.E.) were 0.08±0.03, 0.07±0.03 and 0.05±0.03 for GR1, GR2, and GR3; 0.25±0.07, 0.05±0.02, and 0.01±0.01 for KR1, KR2 and KR3; 0.05±0.03, 0.04±0.02 and 0.00±0.01 for EF1, EF2 and EF3; and 0.09±0.04, 0.05±0.02 and 0.00±0.01 for RGR1, RGR2 and RGR3, respectively. There was little additive genetic variation in growth rate and efficiency-related traits in Iran-Black sheep and therefore, a small genetic progress would be expected through selection. All the studied traits were affected by maternal effects. Estimates of the maternal heritability (m2) ranged from 0.02 (GR3) to 0.13 (EF1) and estimates of the ratio of maternal permanent environmental variance to phenotypic variance (c2) ranged from 0.03 (GR2, GR3, KR2) to 0.09 (GR1, EF3). Genetic correlations between the studied traits varied from -0.63 (KR1 and EF3) to 0.99 (KR2 and EF3), and the phenotypic correlations ranged from -0.65 (GR1 and EF3) to 0.98 (EF2 and RGR2 and EF3 and RGR3). The study also showed the importance of inclusion of efficiency-related traits in selection programs to improve the biological characteristics of Iran-Black sheep.