The objectives were to determine if a diet enriched in alpha-linolenic acid (ALA) would influence ovarian function, early embryo survival, conception rates, and pregnancy losses in lactating dairy cows. Beginning 28 d before breeding, Holstein cows (55 +/- 22 d postpartum; mean +/- SD) were assigned to diets supplemented with either rolled flaxseed (FLAX; 56.7% ALA, n = 62) or rolled sunflower seed (SUNF; 0.1% ALA, n = 59) to provide approximately 750 g of oil/d. Diets continued for 32 d after timed artificial insemination (TAI, d 0) following a Presynch/Ovsynch protocol. Barley silage- and barley grain-based TMR were formulated to meet or exceed National Research Council requirements. Metabolizable protein and net energy for lactation concentrations were similar in the 2 diets. Based upon a mean dry matter intake of 22 kg/d, cows fed FLAX or SUNF consumed > 410 g or < 1 g of ALA, respectively. Pregnancy was confirmed by ultrasound 32 d after TAI. Nonpregnant cows were placed on a second Ovsynch regimen and reinseminated 42 d after first TAI, and received oilseeds for 32 d after second TAI. Relative to prediet levels, FLAX increased the ALA content of milk by 187%. Ovarian ultrasonography was performed in 8 cows per diet; the mean diameter of ovulatory follicles was larger in cows fed FLAX compared with SUNF (16.9 +/- 0.9 vs. 14.1 +/- 0.9 mm), but follicle number, corpus luteum size, and plasma progesterone concentrations remained unaffected. Presumptive conception (progesterone < 1 ng/mL on d 0 and > 1 ng/mL on d 21) rates to first TAI were greater in FLAX than in SUNF (72.6 vs. 47.5%). Pregnancy losses were lower in cows fed FLAX (9.8%) compared with those fed SUNF (27.3%). Including flaxseed in the ration of dairy cows increased the size of the ovulatory follicle and reduced pregnancy losses.

. 2004. Effect of low and high forage diet on enteric and manure pack greenhouse gas emissions from a feedlot. Can. J. Anim. Sci. 84: [445][446][447][448][449][450][451][452][453]. The objectives of this study were to assess enteric methane (CH 4 ) production by beef steers fed one of two isocaloric diets with different forage:grain ratios and to quantify greenhouse gas (GHG) emissions from bedded manure packs in the eight feedlot pens holding these steers (14 head pen -1 ). Five animals (252 ± 20 kg) in each pen were randomly selected for measurement of CH 4 emissions over the course of the 126-d feeding trial. Two 24-h gas collections were completed for each steer in each of three collection periods using the sulfur hexafluoride tracer gas technique. The fluxes of nitrous oxide (N 2 O), methane (CH 4 ) and carbon dioxide (CO 2 ) from bedding packs were measured using vented static chambers in each sampling period. Methane production (L d -1 ) was 42% higher (P < 0.05) from steers fed the low forage:grain ratio than from steers fed the high forage:grain ratio. Overall, methane production (% of gross energy intake) ranged from 0.9 to 6.9% on the low forage:grain diet and from 0.7 to 4.9% on the high forage:grain diet. Daily CH 4 emissions were similar in the first two periods and increased during the third sampling period. There was no effect of diet on manure pack temperature during sampling, however, the manure pack was deeper (P < 0.05) in pens holding animals fed the high forage:grain diet. Furthermore, diet had no effect on the manure pack fluxes. Total daily non-CO 2 emissions from enteric and manure pack sources (CO 2 equivalent) were different (P < 0.05) between dietary treatments and averaged 1931 ± 81 g head -1 d -1 for the low forage:grain and 1394 ± 81 g head -1 d -1 for the high forage:grain diet. . L'étude devait servir à évaluer la production entérique de méthane (CH 4 ) par des bouvillons de boucherie recevant deux rations isocaloriques à rapport fourrage:grain différent ainsi qu'à déterminer le volume de gaz à effet de serre (GES) libérés par la litière accumulée dans les huit enclos où les animaux étaient gardés (14 sujets par enclos). Cinq animaux (252 ± 20 kg) ont été choisis au hasard dans chaque enclos et on a mesuré leurs émissions de CH 4 au cours des 126 jours de l'expérience. Pour chaque bouvillon, on a recueilli les gaz pendant 24 heures à deux reprises dans chacune de trois périodes en utilisant de l'hexafluorure de soufre comme traceur. Les flux d'oxyde nitreux (N 2 O), de méthane (CH 4 ) et de dioxyde de carbone (CO 2 ) issus de la litière accumulée ont été mesurés au moyen de cellules aérées de manière statique durant chaque période d'échantillonnage. Les animaux nourris avec la ration à faible rapport fourrage:grain produisent 42 % plus (P < 0,05) de méthane (litres par jour) que ceux nourris avec l'autre ration. Dans l'ensemble, la production de méthane (pourcentage de la quantité d'énergie brute ingérée) varie de 0,9 à 6,9 % pour la ration à faible rapport fourrage:grain et de 0...

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Appropriate integrin expression appears to be necessary for successful implantation of human embryos and varies considerably among species. The present study was undertaken to determine the distributions of integrin subunits alpha(1), alpha(3), and alpha(6) as well as the extracellular matrix (ECM) components collagen IV and laminin in implanting bovine trophoblast and endometrium. Immunohistochemical staining of cryostat sections prepared from nonpregnant endometrium, of preattachment through to early villus development pregnant endometrium (Days 18, 21, 24, and 30), and of isolated trophoblast binucleate cells was performed. Trophoblast down-regulated the integrin alpha(1) subunit as attachment proceeded, whereas reactivity scores for alpha(6) antibody tended to increase from Day 18 through 24 and remained high. A subpopulation of trophoblast binucleate cells expressed the alpha(3) integrin subunit. Uterine epithelium constitutively expressed alpha(3) and alpha(6) integrin subunits, but the alpha(1) subunit was down-regulated as the luminal epithelium was modified. Collagen IV and laminin reactivity increased in the basal lamina and underlying subepithelial stroma as pregnancy proceeded. The results suggest that binucleate cell fusion with the maternal epithelium initiates integrin and ECM changes in the subepithelial stroma.