the aim followed in the present research was to study the effects of reduction in dietary crude protein on milk production and on blood components in lactating holstein dairy cows when in heat stress. a number of 63 holstein dairy cows (71 ± 16.5 dim) were chosen to be made use of in a randomized complete block design. the cows were randomly assigned to any one of the three experimental rations...

some factors affecting crude protein balance (cpb), as a measure of efficiency, were studied using 2824 records of 501 lactating holstein cows. the cpb (kg d-1) was calculated as crude protein (cp) intake (kg) minus cp yield (kg). two different statistical methods including principal components (pcs) and general linear model analyses were used to study the effects of different factors. crude pr...

osteopontin gene is located at the end of chromosome 6 in cattle and it is one of the most important genes influence on milk protein percentage and reproduction. in this study, blood samples were collected from100 brown swiss cows and dna was extracted from whole blood by modified salting out procedure. cows were genotyped for single nucleotide polymorphism of intron iv by pcr-rflp and bsri res...

the present study was conducted to estimate genetic parameters and genetic, environmental and phenotypic trends of milk production traits in holstein cattle of hamedan province. in this study 11986 305-d records of first three parities of hamedan province holstein cattle, which were gathered during 1990-2011, were used. variance-covariance components and breeding values were estimated using ani...

The effects of fat supplementation and weaning system on commercial milk yield and milk composition were determined on 129 East Friesian crossbred ewes. Prior to lambing, ewes were randomly assigned to one of two weaning systems. The DY1 system involved weaning of ewes from their lambs within 24 to 36 hr post-partum and then twice-daily machine milking. In the MIX system, ewes had access to the...

introduction productive traits such as milk production and fat and protein percentage have economic importance in the livestock industry. accurate prediction of breeding value of animals is one of the best tools available for maximizing response to selection program. it is a fact that the main objective of the breeding program, is to achieve the maximum economic benefit. for breeders of dairy c...

the κ-casein protein plays a fundamental role in milk production and its composition synthesis in the mammary gland. this protein has an important role in the formation, stabilization, and aggregation of the casein micelles. in this study, we investigated the genetic variability at the exon 4 of the κ-casein gene (also known as csn3) using pcr-sscp analysis and dna sequencing. then a protein se...