Akademik Veri Yönetim Sistemi
JOURNAL OF DAIRY SCIENCE, cilt.92, sa.6, ss.2562-2571, 2009 (SCI-Expanded)
The objective of this study was to determine the effects of feed restriction and source of dietary fatty acids during the close-up dry period on postcalving reproductive performance of dairy cattle. Thirty-four days before expected calving, pregnant Holstein cows (n = 72; parity 1 to 5) were randomly assigned to 1 of 6 treatments. Treatments were ad libitum (AL) or 24% feed restriction (FR) in combination with 1 of 3 oilseed supplements at 8% of diet dry matter: canola, linola, or flax to enrich the rations with oleic, linoleic, or linolenic fatty acids, respectively. After calving, cows were fed a common lactation diet that contained no oilseeds. Measurements of uterus, corpus luteum, and follicles were obtained by ultrasonography twice weekly from 7 + 1 d after calving until the first ovulation. Cows (n = 66) were subjected to timed artificial insemination (TAI), and pregnancy was determined 32 d later. Feed-restricted cows had lower dry matter intake and lost more body weight prepartum. Energy balance (Mcal/d) was negative in FR cows prepartum but they had a less severe negative energy balance postpartum. The dietary source of fatty acid did not affect energy balance. Cows fed AL had a higher incidence of uterine infections (10/37 vs. 2/35) but tended to have fewer ovarian cysts (2/37 vs. 7/35) than FR cows. Mean (+SE) interval from calving to uterine involution did not differ among dietary treatments (26.8 + 1.8 d). Interval from calving to first ovulation was longer in cows fed canola than in those fed either linola or flax (34.7 + 3.1 vs. 23.7 + 3.2 and 21.0 + 3.1 d, respectively). A greater percentage of cows fed AL conceived to the first TAI (47.1 vs. 18.8) and tended to have fewer mean days open (157 + 10.8 vs. 191 + 10.1) than cows fed FR. In summary, FR cows had a lower incidence of uterine infections, but they were less fertile as reflected by a lower percent pregnancy to first TAI and increased days open. Cows fed diets enriched in linoleic or linolenic fatty acids had a lesser incidence of ovarian cysts and ovulated sooner with no effect on energy balance or fertility.