Mammals are characterised by their ability to provision offspring with milk, but lactation is normally restricted to females. Why do most males not share this trait? The morphological and physiological modifications necessary for male lactation are possible and, although restrictive, the ecological factors that could select for male lactation seem common enough. Until quite recently, there was ...

The objective of this study was to estimate the relation of body condition score (BCS) near calving to the body condition change in early lactation, the reproductive performance, milk yield and culling rate in the first lactation Estonian Holstein dairy cows. Cows were divided into three groups based on their BCS at calving; thin, BCS ≤3.0 (n=29); moderate, BCS 3.25–3.5 (n= 48); and fat, BCS ≥3...

introduction: lactation yield and persistency are two economic important traits in dairy cow. the production level of a dairy cow is determined by a joint effect of genetic and environmental factors.the main factors determining the total amount of milk production are milk yield at the peak of lactation and persistency as well as length of lactation period. persistency are defined as a extent to...

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 effect of principal components (pc) of the regression coefficients (co)variance matrix on the lactation curve, and on the formation of selection index to modify the curve, based on these pc’s, and as well to estimate additive genetic and phenotypic variances and heritability of the constructed selection index. lactation period of 301 d (5-305) ...

An important branch of the modern global economy is food production. Our focus is milk production on dairy farms, the period in which cows produce milk (lactation) and the quantity of milk produced. Special attention will be given to the time-dependent function that describes the quantity of the milk produced over a lactation period. The respective graph is known as the lactation curve and is o...

Citrate is a normal constituent of milk that affects milk-processing characteristics. It is an intermediate in the tricarboxylic acid cycle and plays an indirect role in fat synthesis by providing reducing equivalents in the form of NADPH. The objective of this study was to investigate variation in citrate with stage of lactation and de novo fatty acid synthesis, without confounding dietary eff...

Although evidence from domestic and laboratory species suggests that reproductive experience plays a critical role in the development of aspects of lactation performance, whether reproductive experience may have a significant influence on milk energy transfer to neonates in wild populations has not been directly investigated. We compared maternal energy expenditures and pup growth and energy de...

Milk and serum samples from 35 dairy herds in 17 states were evaluated for cow- and herd-level Mycobacterium avium subspecies paratuberculosis (MAP) antibody test agreement. Evaluation of 6,349 samples suggested moderate agreement between milk and serum enzyme-linked immunosorbent assay (ELISA) results, with a kappa value of 0.50. Cow-level sensitivity (Se) for 18 dairy operations with 1,921 an...

The Ural type of the domestic black-and-white breed is characterized by high productivity and good suitability for use in conditions industrial milk technology. During its breeding, purebred bulls-producers Holstein both foreign breeding continues. As a result conducted research, it was found that cows changes significantly with age. Milk yield 305 days lactation increases from 1 to 3 lactation...