Effect of a single or double inseminations at fixed-time basis on lambing rate of ewes treated with 2 different progestogen-impregnated intravaginal sponges during the non-breeding season was investigated in 3 trials (Farms T, H and S). A total of 236 mature Suffolk ewes were treated with either 60 mg medroxyprogesterone acetate (MAP)-or 500 mg progesterone (P) impregnated intravaginal sponge for 9 days and an intramuscular injection of 600 IU PMSG one day before sponge removal. The MAP-and P-treated ewes were inseminated once (36 hr) or twice (30 and 42 hr) with fresh-undiluted semen after sponge removal. The lambing rates in 4 groups were 44.6, 50.9, 46.6 and 50.0% for MAP-single, MAP-double, P-single and P-double inseminations, respectively. There were no significant differences in the lambing rates between the two types of sponges (46.5 and 48.3% for MAP and P sponges, respectively) and between the numbers of insemination (45.6 and 50.4% for a single and double insemination, respectively). The lambing rate in Farm H (33.7%) was significantly lower than those in Farms T (50.0%: p<0.05) and S (61.7%: p<0.01).

Four wethers were used in a 4 × 4 Latin square design experiment to evaluate in vivo digestibility of total mixed ration (TMR) silage with food by-products for dairy cows, and the ruminal condition and nitrogen (N) balance were examined. Five by-products (i.e. potato waste, noodle waste, soybean curd residue, soy sauce cake and green tea waste) were obtained. Four types of TMR silage were used: control (C) containing roughage and commercial concentrate, T1:20% and T1:40% containing the five by-products replacing 20% and 40% of the commercial concentrate on a dry matter (DM) basis, respectively, and T2:40% containing three by-products (potato waste, noodle waste and soybean curd residue) replacing 40% of the commercial concentrate on a DM basis. The ingredients were mixed and preserved in oil drum silos for 4 months. The TMR silages showed 4.02-4.44% and 1.75-2.19% for pH and lactic acid contents, respectively. The digestibility of DM and neutral detergent fiber, and total digestible nutrient content were higher (P < 0.05) for T2:40% feeding than for C feeding. Urinary nitrogen excretion tended to be lower (P = 0.07) for T2:40% than for C. The results suggested 40% replacing of commercial concentrate by using the three food by-products can be most suitable for TMR silage.

No abstract

PG concentration is often increased during uterine manipulation with embryo transfer. Embryo viability is affected by the increase in the PGF2α concentration accompanying manipulation of the uterus during embryo transfer. Schrick et al. (2001 Theriogenology 55, 370 abst) observed that treatment with flunixin meglumine, an inhibitor of prostaglandin, increased pregnancy rates depending on the stage and quality of embryos transferred. On the other hand, prostaglandin was secreted by a cumulus cell monolayer in an in vitro culture of bovine oocytes. The present study aimed to assess the effects of flunixin meglumine in culture medium on the development of in vitro-matured and fertilized bovine embryos. COCs were collected from ovaries of slaughtered cows by aspiration. The COCs were matured for 20 h in TCM-199 supplemented with 5% fetal bovine serum (FBS) and antibiotics at 38.5°C under an atmosphere of 2% CO2 in air. Matured COCs were inseminated with 1.0 × 107 sperm mL−1 in BO medium (Brackett and Oliphant 1975 Biol. Reprod. 12, 260–274) containing 5 mM theophillin and 5 μg mL−1 heparin for 5 h. All of the inseminated oocytes were introduced into the maturation medium that had been kept with the cumulus cells in the CO2 incubator. At 48 h after insemination, all embryos over the 4-cell stage were cultured in TCM-199 plus 5% FBS supplemented with each of five concentrations of flunixin meglumine (0, 0.0025, 0.005, 0.01, and 0.025%) with a cumulus cell monolayer. Development to the blastocyst stage and quality were examined at Days 7 to 8 (Day 0 = day of insemination) using a microscope. The experiment was replicated four times. Data were analyzed by the chi-square test. The total blastocyst rates from the over-4-cell embryos were 61.2 (52/89), 53.7 (44/89), 65.6 (59/90), 57.3 (51/89), and 33.7% (31/92) for 0, 0.0025, 0.005, 0.01, and 0.025%, flunixin meglumine, respectively. The total blastocyst rate with the flunixin meglumine concentration of 0.025% was significantly lower than those with the other concentrations (P < 0.05). The proportion of grade 1 blastocysts with the flunixin meglumine concentration of 0.005% was significantly higher than that with the 0, 0.0025, and 0.025% concentrations (27.8 vs 11.2, 14.6, and 5.4%; P < 0.05). Our present results show that the addition of 0.005% flunixin meglumine to the co-culture medium is positively associated with blastocyst quality in bovine embryos.

Repeat-breeding is one of the important factors that affect dairy management. The objective of this study was to investigate the effect of transfer of frozen–thawed IVF embryos on pregnancy in repeat-breeder Holstein cattle. Cumulus–oocyte complexes (COCs) were collected by aspiration of 2–1-mm follicles from ovaries obtained at a local abattoir. COCs were matured for 20 h in TCM-199 supplemented with 5% calf serum (CS) and 0.02 mg/mL of FSH at 38.5°C under a 5% CO2 atmosphere in air. Matured oocytes were inseminated with spermatozoa of 5 × 106/mL in BO solution (Brackett and Oliphant 1975 Biol. Reprod. 12, 260–274) containing 10 mM hypotaurine and 4 units/mL heparin. After 18 h of gamete co-culture, presumptive zygotes were cultured in CR1aa (Rosenkrans et al. 1991 Theriogenology 35, 266) supplemented with 5% CS for 8 days at 38.5°C under 5% CO2, 5% O2, 90% N2 atmosphere in air. After in vitro fertilization, Day 7 and Day 8 blastocysts were frozen in 1.5 M ethylene glycol (EG) in Dulbecco's PBS (DPBS) supplemented with 0.1 M sucrose and 20% CS. Embryos were transferred into a freezing medium, loaded into 0.25-mL straws, and allowed to stand for 15–20 min for equilibration. The straws were then plunged into a −7°C methanol bath of a programmable freezer for 1 min, seeded at −7°C, maintained at −7°C for 15 min, cooled to −30°C at the rate of −0.3°C/min, and then plunged into liquid nitrogen. Recipient animals (43 heifers, 131 cows) included those that did not conceive after being artificially inseminated (AI) 3 to 15 times. The frozen–thawed IVF embryos were directly transferred to the recipient animals 7 days after estrus or AI. Pregnancy rates were analyzed by chi-square test. The results are presented in Table 1. There were no significant differences in the pregnancy rates between treatments. However, a slightly higher pregnancy rate was achieved by embryo transfer after AI. These results suggest that embryo transfer may increase the pregnancy rate in repeat-breeder Holstein cattle. Table 1. Pregnancy rates after transfer of IVF frozen–thawed embryos in repeat-breeder Holstein cattle