Phenotypic and genetic correlations were estimated between 48 type appraisal traits and first lactation milk production to determine the importance of appraisal traits in a breeding program from 5,024 records from the New York type appraisal program. Most phenotypic correlations amgng the type traits were near zero. Depth of udder was the appraisal trait having the highest correlation with firs...

The objective of this study was to investigate the association of polymorphisms at the STAT5A and FGF2 gene loci with fertility, lactation milk yield and lameness in dairy cattle. Five hundred and eighteen primiparous Holstein cows were included in the study. Several reproductive traits were considered including conception rate (0/1) at first insemination, conception rate (0/1) in a 305-day lac...

Milk yield records from 1 to 5 lactations of Iranian Holstein cows were analyzed using repeatability and a number of multivariate models that varied in additive genetic variance structure. A total of313,006 milk yield records were used. The records were obtained from 116,531 cows born between 2001 and 2005. The animals originated from 2,355 sires and 91,212 dams. A multivariate model with heter...

Cattle chromosome 6 was scanned with 11 markers, ten microsatellites and the casein haplotype, to identify quantitative trait loci (QTLs) affecting the following milk production traits: milk yield, fat percentage, fat yield, protein percentage and protein yield. Twelve Finnish Ayrshire half-sib families with a total of 480 sons were genotyped and used in a grand-daughter design. Interval mappin...

DGAT1 encodes diacylglycerol O-acyltransferase (EC ), a microsomal enzyme that catalyzes the final step of triglyceride synthesis. It became a functional candidate gene for lactation traits after studies indicated that mice lacking both copies of DGAT1 are completely devoid of milk secretion, most likely because of deficient triglyceride synthesis in the mammary gland. Our mapping studies place...

Economic values of milk volume (VOL), fat yield (FYLD), protein yield (PYLD), live weight (LWT), longevity (LON), calving interval (CIV) and somatic cell score (SCS) were derived for Holstein and Jersey cattle, based on milk payment systems of four major milk buyers in South Africa. The economic value of somatic cell score was calculated for only two of the payment systems. A bio-economic model...

The objective of this work was to estimate genetic parameters for the Italian population of river buffaloes. Lactation records (10,663) for milk, fat, protein and mozzarella cheese production of river buffalo cows were analyzed by fitting a multiple trait animal model using restricted maximum likelihood. The number of cows with records was 3873 with 6842 animals in the relationship matrix. mozz...

Rubber flooring in dairy cows has been discussed controversially, because different studies found as well advantages as disadvantages regarding claw health. Until today little is known regarding the effect of rubber flooring on the reproductive performance of dairy cows. Therefore, the study aimed at comparing fertility and the milk yield of dairy cows on concrete or rubber flooring. Days to fi...

specific trait candidate genes are sequenced genes with known biological activity. the effects of pou1f1 and stat5a on milk production traits have been studied in several studies. pou1f1 affects on transcription of prolactin and growth hormone gene, as well as, stat5a is known as a main mediator of growth hormone action on target genes and intracellular mediator of prolactin signaling. since th...

All rights reserved. Readers may make verbatim copies of this document for non-commercial purposes by any means, provided that this copyright notice appears on all such copies. ABSTRACT The objective of the study was to assess the farm level economic implications of value-adding genetic selection strategies to improve milk fat composition. Selection based on a quantitative trait (ratio of total...