Name: Effects of Feeding Fish Meal and n-3 Fatty Acids on Ovarian and Uterine Responses in Early Lactating Dairy Cows

Authors: A.R.Heravi Moussavi*R.O.Gilbert†T.R.Overton‡D.E.Bauman‡W.R.Butler‡

Address: *Department of Animal Science, Ferdowsi University, Mashhad 91775-1163, Iran,†Department of Clinical Sciences, Cornell University, Ithaca, NY 14853, ‡ Department of Animal Science, Cornell University, Ithaca, NY 14853

Abstract: The study was designed to test the effects of dietary supplementation with fish meal or specific n-3 fatty acids on ovarian activity and uterine responses in early lactating cows. From 5 to 50 d in milk (DIM), cows were fed diets that were isonitrogenous, isoenergetic, and isolipidic containing none (control), 1.25, 2.5, or 5% menhaden fish meal (FM) or 2.3% Ca salts of fish oil fatty acids (CaFOFA). Ovarian follicular dynamics were monitored along with plasma concentrations of estradiol and progesterone. Beginning at 23 DIM, cows were induced into a synchronized ovulatory cycle. On d 15 after ovulation (49 DIM), cows were injected with oxytocin and blood samples were collected to monitor uterine release of PGF۲α (measured as 13, 14-dihydro-15-keto PGF۲α; PGFM). Uterine endometrial biopsies were collected for fatty acid analysis and cyclooxygenase-2 (COX-2) protein measurement. Ovarian follicular activities as well as plasma estradiol and progesterone concentrations were similar across diets. Endometrial fatty acid composition of eicosapentaenoic acid (C20:5, n-3) and docosahexaenoic acid (C22:6, n-3) were increased as much as 3-fold by supplementation with fish meal and CaFOFA. Conjugated linoleic acid (C18:2 cis-۹, trans-۱۱) in the endometrium was also increased; conversely, arachidonic acid (C20:4, n-6) percentage was decreased by 5% FM. Plasma PGFM response to oxytocin injection was not different among diets and endometrial COX-2 protein abundance did not differ. Results from this experiment demonstrate that dietary supplementation with fish meal or n-3 fatty acids in early lactating dairy cows significantly increased uterine n-3 fatty acid concentrations, but had no apparent effect on endometrial COX-2 or PGF۲α production in response to oxytocin challenge.

Key Words: cow, fish meal, cyclooxygenase-2 protein, n-3 fatty acids

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Name: Effects of dietary unsaturated fatty acids on oocyte quality and follicular development in lactating dairy cows in summer

Authors: T R Bilby ۱, J Block, B C do Amaral, O Sa Filho, F T Silvestre, P J Hansen, C R Staples, W W Thatcher

Address:۱Department of Animal Sciences, University of Florida, Gainesville, Florida 32611-0910, USA.

Abstract: Dietary sources of fatty acids were evaluated for their influence on oocyte quality and follicular development using 54 lactating cows in summer. Fat supplements were 1) sunflower oil (80% cis 18:1), 2) Ca salt of transoctadecenoic acids (57% trans ۱۸:۱), ۳) Ca salt of vegetable oils (30% 18:2), and 4) linseed oil (56% 18:3 and 16% 18:2). Fats were fed at 1.35% of dietary dry matter beginning at 5 wk prior to expected calving date and at 1.5% (oils) and 1.75% (Ca salts) of dietary dry matter for 15 wk after parturition. Four days following a programmed induced ovulation, 5 transvaginal oocyte aspirations were performed 3 or 4 d apart. Three days after the last aspiration, PGF۲α was injected, followed 3 d later by a GnRH injection and a timed artificial insemination (d 0) 16 to 20 h later. For the first 4 aspirations, oocytes grading 1 or 2 were used for in vitro embryo production. Total cell number and the proportion of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)–positive blastomeres were analyzed at d 8. At the fifth aspiration, the occurrence of metaphase II, group II caspase activity, and TUNEL labeling were determined after oocyte maturation. A total of 1,011 oocytes were collected. The proportion of oocytes with high caspase activity was greater for grade 3 compared with grades 1 and 2 (37.5 vs. 1.54 and 1.61%). Feeding polyunsaturated fatty acids, as compared with monosaturated fatty acids, failed to affect oocyte quality, as demonstrated by subsequent embryo development. Cows fed 18:2- or 18:3-enriched diets had a larger preovulatory follicle at insemination and subsequent volume of the corpus luteum compared with those fed cis ۱۸:۱ or trans ۱۸:۱ diets (16.8, 16.2 vs. 15.0, 14.9 ± ۰.۷ mm; 7,323, 8,208 vs. 6,033, 5,495 ± ۶۴۴ mm۳, respectively). The previously documented benefits of polyunsaturated fatty acids on reproductive performance appear to reflect actions at alternative biological windows in lactating dairy cows.

Key Words: fatty acid, embryo, oocyte, cow

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Name: Feeding and Managing Cows to Minimize Heat Stres

Authors: L.H. Baumgard 1,3 , M.K. Abuajamieh 1 , S.K. Stoakes 1 , M.V. Sanz-Fernandez 1,
J.S. Johnson 1 and R.P. Rhoads 2

Address: ۱ Iowa State University, 2 Virginia Tech University

Abstract: Environmental-induced hyperthermia compromises eI¿cient animal production
and jeopardizes animal welfare. Reduced productive output during heat stress was traditionally thought to result from decreased nutrient intake. Our observations challenge this dogma and indicate heat-stressed animals employ novel homeorhetic strategies to direct metabolic and fuel selection priorities independently of nutrient intake or energy balance. Thus, the heat stress response markedly alters post-absorptive carbohydrate, lipid, and protein metabolism, independently of reduced feed intake through coordinated changes in fuel supply and utilization by multiple tissues.
There may be nutritional, pharmaceutical, and managerial options to take advantage of these
aforementioned metabolic changes to improve productivity and animal welfare during the warm summer months.

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