Associations among dairy cow body condition and welfare-associated behavioral traits.

Some evidence exists that cow body condition score (BCS) is associated with risks to animal health, and that higher BCS in extensively kept animals provides a buffer against cold conditions or other adverse weather events. Not surprisingly, measures of BCS feature in dairy cattle welfare assessment protocols. However, the degree to which BCS predicts welfare state, particularly in relation to the level of "hunger" experienced, is not well researched.

Genetic strain and diet effects on grazing behavior, pasture intake, and milk production.

Understanding how dairy cows adjust their grazing behavior in response to feed supplements is important for the development of management strategies that optimize profit from supplementation. New Zealand Holstein-Friesian (HF) cows have been selected for milk production on a predominantly pasture-based diet; in comparison, HF cows of North American (NA) ancestry have been selected almost exclusively for milk yield and fed diets high in nonfiber carbohydrates (NFC). We hypothesized, therefore, that supplementation would have differing effects on grazing behavior, pasture dry matter intake (DMI), and milk production in these genetic strains at peak, mid, and late lactation.

Effects of divergent Holstein-Friesian strain and diet on diurnal patterns of plasma metabolites and hormones.

Commonly measured metabolite and hormone concentrations used to describe the metabolic status of lactating cows undergo diurnal variation resulting in distinct patterns. Studies have shown that feeding events can modulate these diurnal patterns as cows respond to the nutrient intake. What is less clear is the extent to which cow genetics and diet interact to modify the diurnal patterns of specific nutritionally related metabolites and hormones.

Extending lactation in pasture-based dairy cows. II: Effect of genetic strain and diet on plasma hormone and metabolite concentrations.

Fifty-six genetically divergent New Zealand and North American Holstein-Friesian (HF) cows grazed pasture, and were offered 0, 3, or 6 kg of concentrate DM/cow per day for an extended lactation (605 +/- 8.3 d in milk; mean +/- standard error of the mean). Weekly blood samples collected from individual cows from wk 1 to 10 postpartum (early lactation), and from wk 47 to 63 postpartum (extended lactation) were analyzed for nonesterified fatty acids (NEFA), glucose, insulin, leptin, growth hormone (GH), insulin-like growth factor-I (IGF-I), calcium, and urea.

Comparing subpopulations of plasma progesterone using cluster analyses.

The production of progesterone during the luteal phase of the estrous cycle regulates early embryonic development, uterine function, and luteal function. Plasma progesterone concentrations were measured during a spontaneous estrous cycle in lactating Holstein-Friesian cows of New Zealand or North American ancestry, fed either fresh pasture or a total mixed ration. Subpopulations of profiles were identified using 2 approaches: 1) shape-based clustering and 2) trait-based clustering.