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Effect of breeding regime on percent ova fertilized in superovulated cows
THERIOGENOLOGY EFFECT
OF BREEDING
REGIME ON PERCENT SUPEROVULATED COWS
OVA FERTILIZED
IN
GEORGE WEST, CHRISTOPHER WEST, DART RISLEY AND LLOYD DONALDSON Rio Vista International, Inc. Rt 9 Box 242 San Antonio, Texas 78227 Three experiments were conducted to study the effect of breeding regime on fertilization of ova in superovulated cows. Cows were superovulated using a total of 28 or 40 mg FSH-P(Burns Biotec, Omaha, NE) in descending divided doses over 4 days. On the third day prostaglandin F alpha(Lutalyse, The Upjohn Co., Kalamazoo, MI) (PGF) i6 three divided 30-15-15mg, doses or 250 mcg cloprostenol(Estrumate, Haver-Lockhart, Shawnee, KS) was administered to control estrus. Cows were bred with frozen semen from a small number of bulls of proven high fertility. Embryos and ova were collected non-surgically and were classified as fertilized if there was any evidence of cleavage. In the first experiment, cows were bred with one straw of semen per breeding. A total of 120 cows were allocated at random to one, two or three breedings. One breeding was done 12 hours after the detection of estrus, two breedings were performed at 12 and 24 hours while three breedings were done at detection of estrus and 12 and 24 hours later. A further 85 cows were bred three times and included in the results. Only those cows detected in estrus are included in the results. The fertilization % was 59.4%, 64.7% and 62.7% for 30, 37 and 119 cows bred one, two and three times, respectively (by ANOVA P = 0.858). The % embryos transferable was 33, 41 and 44% (by ANOVA P = 0.2931 out of the total embryos collected of 7.7, 8.5 and 10.1 (by ANOVA P = 0.256). In the second experiment the quantity of semen used was increased to two straws at the breeding 12 hours after the detection of estrus. A total of 210 cows were allocated at random to one, two or three breedings. Then the third breeding group was discontinued, and forty cows were treated in groups with one or two breedings. Then one breeding was dropped and a further 70 cows treated with two breedings. The % fertilized was 58, 73 and 77%,respectively, for 88, 157 and 69 cows bred once, twice or three times (by students t test 2>1, P = 0.005; 3>1, P = 0.003); while the % transferable was 28%, 47% and 54% (by students t test 2>1, P1, P
1984 VOL. 21 NO. I
273
OF BREEDING
REGIME ON PERCENT SUPEROVULATED COWS
OVA FERTILIZED
IN
GEORGE WEST, CHRISTOPHER WEST, DART RISLEY AND LLOYD DONALDSON Rio Vista International, Inc. Rt 9 Box 242 San Antonio, Texas 78227 Three experiments were conducted to study the effect of breeding regime on fertilization of ova in superovulated cows. Cows were superovulated using a total of 28 or 40 mg FSH-P(Burns Biotec, Omaha, NE) in descending divided doses over 4 days. On the third day prostaglandin F alpha(Lutalyse, The Upjohn Co., Kalamazoo, MI) (PGF) i6 three divided 30-15-15mg, doses or 250 mcg cloprostenol(Estrumate, Haver-Lockhart, Shawnee, KS) was administered to control estrus. Cows were bred with frozen semen from a small number of bulls of proven high fertility. Embryos and ova were collected non-surgically and were classified as fertilized if there was any evidence of cleavage. In the first experiment, cows were bred with one straw of semen per breeding. A total of 120 cows were allocated at random to one, two or three breedings. One breeding was done 12 hours after the detection of estrus, two breedings were performed at 12 and 24 hours while three breedings were done at detection of estrus and 12 and 24 hours later. A further 85 cows were bred three times and included in the results. Only those cows detected in estrus are included in the results. The fertilization % was 59.4%, 64.7% and 62.7% for 30, 37 and 119 cows bred one, two and three times, respectively (by ANOVA P = 0.858). The % embryos transferable was 33, 41 and 44% (by ANOVA P = 0.2931 out of the total embryos collected of 7.7, 8.5 and 10.1 (by ANOVA P = 0.256). In the second experiment the quantity of semen used was increased to two straws at the breeding 12 hours after the detection of estrus. A total of 210 cows were allocated at random to one, two or three breedings. Then the third breeding group was discontinued, and forty cows were treated in groups with one or two breedings. Then one breeding was dropped and a further 70 cows treated with two breedings. The % fertilized was 58, 73 and 77%,respectively, for 88, 157 and 69 cows bred once, twice or three times (by students t test 2>1, P = 0.005; 3>1, P = 0.003); while the % transferable was 28%, 47% and 54% (by students t test 2>1, P
1984 VOL. 21 NO. I
273