Interrelationships between energy balance and postpartum reproductive function in dairy cattle.

Undesirable side effects of selection for high production efficiency in farm animals: a review

Risk factors for post partum ovarian dysfunction in high producing dairy cows in Belgium: a field study.

Fertility in the high-producing dairy cow ☆

The objectives of this study were to characterize early postpartum (PP) follicular development in dairy cows and to evaluate the influence of energy balance (EB) and the level of dietary fat on dominant follicle development and function. Forty-five multiparous Holstein cows were fed either low (LF, 3.3%), moderate (MF, 5.2%), or high (HF, 7.1%) total dietary fat beginning at parturition, and daily EB was determined for all cows. Follicular development was monitored by ultrasonography, and blood plasma was analyzed for metabolites, metabolic hormones, progesterone, estradiol, and FSH. After an increase (p 15 mm) follicles on Day 14 PP as compared to the LF diet. Cows fed the MF diet had higher (p 10 mm) dominant follicles was not a limiting factor in PP reproductive recovery, and moderate dietary fat shortened the interval to first ovulation. Follicular competence early PP was associated with higher plasma IGF-I and a shorter interval to the EB nadir.

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Energy Balance and Ovarian Follicle Development Prior to the First Ovulation Postpartum in Dairy Cows Receiving Three Levels of Dietary Fat

Energy balance and serum progesterone concentrations were monitored during early lactation in a group of high producing Holstein cows. The postpartum interval to normal ovulation averaged 36 +/- 6 days (range 6 to 83 days). Average energy balance during the first 20 days of lactation (cumulative daily calculated energy balance divided by days in milk) was inversely related to days to normal ovulation (r = -.60) and to milk production (r = -.80). Milk yield during this period was not closely related to days to ovulation (r = .30). Milk yield was also not significantly related to serum prolactin concentrations over the first 12 weeks of lactation (r = .27). During early lactation, energy balance was maximally negative until peak milk yield and then began returning toward zero, with the magnitude and duration of negative energy balance being quite variable. On the average, ovulation and the initiation of the first normal luteal phase occurred approximately 10 days after energy balance began returning toward zero. During this 10-day interval, a transient elevation in serum progesterone concentrations occurred in eight of 13 cows. These results suggest that energy balance during the first 20 days of lactation is important in determining the onset of ovarian activity following parturition.

R. W. Everett

Papers

The relationships between energy balance, milk production and ovulation in postpartum Holstein cows

Variation in Forage Preference in Dairy Cattle1