Genome-wide association studies for methane emission and ruminal volatile fatty acids using Holstein cattle sequence data.

Background: Methane emission by ruminants has contributed considerably to the global warming and understanding the genomic architecture of methane production may help livestock producers to reduce the methane emission from the livestock production system. The goal of our study was to identify genomic regions affecting the predicted methane emission (PME) from volatile fatty acids (VFAs) indicators and VFA traits using imputed whole-genome sequence data in Iranian Holstein cattle.

Results: Based on the significant-association threshold (p < 5 × 10), 33 single nucleotide polymorphisms (SNPs) were detected for PME per kg milk (n = 2), PME per kg fat (n = 14), and valeric acid (n = 17).

Association between single nucleotide polymorphism in the ovine DGAT1 gene and carcass traits in two Iranian sheep breeds.

The aim of the study was to investigate the single nucleotide polymorphisms (SNPs) at 16-17 exon of DGAT1 gene in Lori-Bakhtiari sheep (LB) and Zel sheep (Z) breeds and provide a foundation for studying the relationship of DGAT1 gene with some carcass traits and the genetic relationship between LB sheep and Z sheep breeds. A total of 309 sheep were slaughtered and the carcass weight, backfat thickness, fat-tail weight, fat-tail percentage, dressing percentage, and dressing percentage adjusted to fat-tail weight were measured. Single nucleotide polymorphism was detected by comparing sequences of PCR products, and the restriction fragment length polymorphism (RFLP) technique was adopted for genotyping.

Direct and maternal (co)variance components, genetic parameters, and annual trends for growth traits of Makooei sheep in Iran.

Genetic parameters and genetic trends for birth weight (BW), weaning weight (WW), 6-month weight (6MW), and yearling weight (YW) traits were estimated by using records of 5,634 Makooei lambs, descendants of 289 sires and 1,726 dams, born between 1996 and 2009 at the Makooei sheep breeding station, West Azerbaijan, Iran. The (co)variance components were estimated with different animal models using a restricted maximum likelihood procedure and the most appropriate model for each trait was determined by Akaike's Information Criterion. Breeding values of animals were predicted with best linear unbiased prediction methodology under multi-trait animal models and genetic trends were estimated by regression mean breeding values on birth year.

Genetic parameter estimates for growth traits and prolificacy in Raeini Cashmere goats.

The main objectives of this study were to estimate genetic and phenotypic parameters for growth traits and prolificacy in the Raeini Cashmere goat. Traits included, birth weight (BWT), weaning weight (WWT), 6-month weight (6WT), 9-month weight (9WT), 12-month weight (12WT), average daily gain from birth to weaning (ADG1), average daily gain from weaning to 6WT (ADG2), average daily gain from 6WT to 12WT (ADG3), survival rate (SR), litter size at birth (LSB) and litter size at weaning (LSW) and total litter weight at birth (LWB). Data were collected over a period of 28 years (1982-2009) at the experimental breeding station of Raeini goat, southeast of Iran.

Monthly variation of plasma concentrations of testosterone and thyroid hormones and reproductive characteristics in three breeds of Iranian fat-tailed rams throughout one year.

Nine sexually mature rams, three Shall, three Afshari and three Zandi were used in this study. Semen of rams was collected twice per month during the four seasons of the year and blood samples were obtained via jugular vein. Seminal characteristics, scrotal dimension and blood parameters were measured at 2 week intervals.