The discussion of effects of recombinant bovine somatotropin (rbST) administration on the metabolism of lactating dairy cows presented is divided into two parts: short term and long term. Short-term effects are evident during the initial period of treatment when milk production is increased but feed intake has not yet increased. During this period body reserves are mobilized to support the high...

After parturition, dairy cows suffer from an intense energy deficit due to the onset of copious milk secretion and an inadequate increase in voluntary food intake. We previously showed that this energy deficit contributes to a decline in plasma leptin. This decline mirrors that of plasma insulin, but is reciprocal to the profile of plasma growth hormone (GH), suggesting that both hormones may r...

Grazing behavior exhibited by different biological types (breed groups) of lactating beef cows was evaluated during the summers of 1985 (Trial 1) and 1986 (Trial 2). Animals grazed native Montana foothill grassland. In Trial 1, breed groups consisted of Hereford (HH), 50% Angus-50% Hereford (AH), 50% Simmental-50% Hereford (SH), and 75% Simmental-25% Hereford (3S1H) with six cows per breed grou...

Aim: This study was conducted to evaluate the concentrations of sodium (Na+) and potassium (K+) ions in milk of lactating dairy cows with and without subclinical mastitis as putative indicators for detecting subclinical mastitis in dairy cows. Materials and Methods: Thirty seven lactating dairy cows were screened for the evidence of subclinical mastitis using California mastitis test (CMT). The...

Energy is the most limiting nutritional component in diets for high-producing dairy cows. Palmitic (C16:0) and stearic (C18:0) acids have unique and specific functions in lactating dairy cows beyond a ubiquitous energy source. This review delineates their metabolism and usage in lactating dairy cows from diet to milk production. Palmitic acid is the fatty acid (FA) found in the greatest quantit...

The objectives of this study were to evaluate effects of feeding propylene glycol (PG) on feed intake, milk yield and milk composition, blood metabolites and energy balance in Holstein dairy cows from 1 to 63 days in milk. Thirty-two multiparous cows, blocked by lactation number, previous 305-day milk production and expected calving date, were arranged into four groups in a randomized block des...

The objective of this study was to determine whether bovine embryos become more resistant to deleterious effects of maternal heat stress as early embryonic development progresses. Superovulated, lactating Holstein cows were bred by AI and assigned to be heat stressed on d 1, 3, 5, or 7 of pregnancy (d 0 =day of estrus) or not heat stressed (control). Embryos were retrieved from the uterus on d ...

The objective of this study was to describe the incidence of papillomatous digital dermatitis in the US (including regional and herd size patterns) and to evaluate specific herd-level management factors associated with high incidence of digital dermatitis in US dairy herds. The study design was a population-based cross-sectional survey. US dairy operations with at least 30 cows in 20 states, re...

To produce milk that is healthier for human consumption, the present study evaluated the effect of including canola oil in the diet of dairy cows on milk production and composition as well as the nutritional quality of this milk fat. Eighteen Holstein cows with an average daily milk yield of 22 (± 4) kg/d in the middle stage of lactation were used. The cows were distributed in 6 contemporary 3x...

Heat stress has profound negative effects in lactating cows, and some of that response is due to depressed dry matter intake (Collier et al., 2006). Recent evidence suggests that other physiological insults related to the heat are responsible for the remaining negative effects on yield, which indicates that alternate coping mechanisms are active in the cow that may affect other production endpo...