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...

Eighteen multiparous early lactation Holstein cows were assigned to a replicated 3 × 3 Latin square with 28-d periods to evaluate milk protein production potential when corn silage (CS) or small grain silage (SGS) was added to diets based on alfalfa silage (AS). Treatments consisted of all AS, a mixture of AS and CS, or a mixture of AS and SGS. Treatment diets were isonitrogenous, isofibrous, a...

Random regression models (RRM) are used for genetic estimations of milk traits in dairy cows. RRM utilize data on traits that are repeated during the time, such as milk trait, which allows of the evaluation of the test day production information. In this study, to estimate genetic parameters for milk production trait, test day records (TDR) were collected from the first lactation of Holstein co...

This review describes the effects of milking (routine and management) on milk yield and milk quality on dairy ruminants and examines the physiological effects of milking on the synthesis and secretion of milk. During milking, differences in the composition of milk as a result of milk ejection reflex are observed: the cisternal milk, immediately available, contains little fat, then milk ejection...

Milk yield from 273 Angus- and Hereford-sired cows and preweaning performance of their calves were used to determine how accurately milk EPD of Angus and Hereford sires predicted milk production of crossbred daughters and subsequent calf performance. Mean milk EPD (kg) for high Angus (HA), low Angus (LA), high Hereford (HH), and low Hereford (LH) bulls (n = 41) selected as sires were +8.7, -6.2...

Received: 7 March, 2014 Accepted: 21 May, 2014 Published: 20 July, 2014 The data consisted of 37118 TD milk record of 5851 primiparous Holstein cows of Tunisia. Herd-years of calving means for milk production traits were clustered in three levels using the CLUSTER procedure in SAS software. Production levels included low, medium and high levels. Genotype by environment interaction were investig...

Understanding cattle metabolism and its relationship with milk products is important in bovine breeding. A systemic view could lead to consequences that will result in a better understanding of existing concepts. Topological indices and quantitative characterizations mostly result from the application of graph theory on biological data. In the present work, the enzyme network involved in cattle...

Veira, D. M., Charmley, L. L., Charmley, E. and Lee, A. J. 2001. The effect of feeding soybean oil to mid-lactation dairy cows on milk production and composition and on diet digestion. Can. J. Anim. Sci. 81: 425–428. Mid-lactation Holstein cows were used to test the effect of feeding 3% soybean oil (SBO) on total mixed ration intake, apparent digestibility, milk production, and milk composition...

this study was conducted to evaluate the effects of extruded linseed on milk production, dry matter intake and reproduction performance of 300 holstein lactating cows (35±15 days in milk; 41±9/8 kg/day of milk production). cows were utilized in a completely randomized experimental design, comprised of: 2 treatments (concentrate containing 7 percent extruded linseed vs control) with a number of ...

Procedures for selecting sires are compared in terms of making maximum genetic progress in economic lnerit. A quadratic index, a simplified form of the quadratic index and a linear index to evaluate economic merit, and a restricted index to improve milk as much as possible while holding milk fat percentage constant, all result in nearly equal expected genetic progress in economic merit. Selecti...