E.O. Oyedipe

Plasma progesterone concentrations during the oestrous cycle and following fertile and non-fertile inseminations of Zebu heifers

Two separate studies were conducted to determine the profiles of plasma progesterone concentrations during the oestrous cycle and early pregnancy in Zebu cattle. Thirty-three Bunaji (Zebu) heifers aged between three and four years were used. In experiment 1, blood samples were collected from 17 heifers by jugular vein puncture at two-day intervals during the oestrous cycle preceding AI. Further blood samples were collected up to 30 days after AI or until the heifers came in heat. In experiment 2, 16 heifers were treated with 25 mg PGF2α during mid-luteal phase. All heifers were inseminated (AI) at observed oestrus and pregnancy diagnosis done at 60 days after AI. Blood samples for plasma were collected as described earlier beginning from the day of injection up to 30 days after AI or until they came in heat. All plasma samples were analysed for progesterone by radioimmunoassay. Plasma progesterone levels increased from day 4 after oestrus and reached a peak of about 3 ± 2·5 ng/ml on day 10 and then declined gradually thereafter to non-detectable levels on day 18. Plasma progesterone concentrations for the pregnant and non-pregnant heifers were compared up to day 16 post AI. The oestrous cycle length following non-fertile inseminations (23·7 ± 1·8 days) was significantly longer (P < 0·05) than that preceding AI (20·0 ± 2·3 days). During the period under comparison, plasma progesterone values were also generally higher (though not significant) for the pregnant than for the non-pregnant heifers following synchronization of oestrous and AI. The results suggest a normal pattern of progesterone profile during the oestrous cycle and comparatively higher progesterone levels in pregnant than in inseminated non-pregnant Zebu cattle during early pregnancy.

Estrus response of indigenous Nigerian Zebu cows after prostaglandin F2 alpha analogue treatment under continuous observations for two seasons

The study was undertaken to determine the estrus response pattern of Zebu cows indigenous to Nigeria following treatment with prostaglandin F2alpha analogue and to determine the effect of season on the estrus parameters. Eighty cyclic Zebu cows were used in both the dry and wet seasons. Two single intramuscular injections of 25 mg of PGF2alpha analogue were given per cow 11 days apart regardless of the stage of the estrous cycle. The cows were then observed continuously for 168 h following each injection. The proportion of treated cows responding to PGF2alpha treatment in the wet season (90%) was significantly higher (P<0.005) than in the dry season (70.0%). The mean post-injection interval to onset of non-standing estrus (mucus discharge) was 30.6 h and 28.5 h in the dry and wet seasons, respectively. Similarly, the intervals to standing estrus were 69.7 h and 63.9 h in the two seasons, respectively. Seasonal effects were not significant. The duration of non-standing estrus was similar for the two seasons (164.2 h and 162.0 h) while the duration of standing estrus was significantly (P<0.01) longer in the wet season (19.2 h) than in the dry season (12.6 h). Also there was seasonal influence on the body condition score of cows, the palpability of corpora lutea (CL) and the intensity of estrus as determined by the number of mounts (17.9+/-2.0 and 51.2+/-3.4 mounts per cow per estrus period in the dry and wet seasons, respectively).

Influence of season on characteristics of the ejaculate from bulls in an artificial insemination centre in Nigeria

The influence of season on the ejaculate characteristics of Zebu, Friesian and their crossbred bulls in an A.I. programme in Nigeria was investigated over a 2-year period. Ejaculate volume, sperm concentration, percent morphologically normal spermatozoa and percent live spermatozoa were significantly higher in the rainy season than in the dry season. Total spermatozoa per ejaculate averaged 3.32 × 109 and 10.10 × 109 for the dry and rainy seasons respectively. Corresponding proportions of total morphologically defective spermatozoa per ejaculate were 14.05% and 6.46%. Percent live spermatozoa were 82.34% and 84.61% while the corresponding sperm concentrations were 0.97 × 109 rmand 1.74 × 109 for the dry and rainy seasons respectively. All differences were statistically significant (P < 0.05). Ejaculate quality was better during the rainy season. Consequently semen collected and frozen during the rainy season may produce higher fertility rates in an A.I. programme.

The Effect of Protein Intake on Body Weight, Scrotal Circumference and Semen Production of Bunaji Bulls and their Friesian Crosses in Nigeria

Scrotal circumference, body weight and semen production traits of Bunaji (BJ) and Friesian X Bunaji (FR X BJ) bull calves fed isocaloric diets of low and high protein levels were investigated for 16 months. The isocaloric rations (2.40 Mcal ME/kg DM) contained crude protein levels of 14.45% (high protein) and 8.51% (low protein). The bulls were electroejaculated biweekly and, on each occasion, body and scrotal measurements and body condition score were taken. The level of protein was found to have a significant influence on physical body growth and semen production traits. Bulls on high protein rations had significantly larger scrotal circumference, greater body weight, higher average daily gains, and higher body condition score than those on low protein diets. Volume of semen, sperm motility, semen concentration and total spermatozoa were significantly (P<0.05) higher for bulls on the high than those on the low protein diet. The FR X BJ achieved higher average daily gains, higher body weights, larger scrotal circumference, higher sperm concentration and total spermatozoa than BJ. There were no significant breed differences in condition score, volume of semen and sperm motility. Body and scrotal size and semen production traits increased significantly with age. Adequate protein intake and good management of young selected sires at breeding centres are essential for optimum sperm cell production.

Effect of dose of pregnant mare serum gonadotrophin on estrus parameters, ovulation rate and peripheral progesterone concentrations in Yankasa ewes

Abstract Estrus was synchronized in 30 mature Yankasa ewes using progestagen pessaries containing 45 mg Flugestone acetate. Animals were divided into five equal groups and treated, at sponge withdrawal with 0, 250, 500, 750 and 1000 IU PMSG (i.m.). Estrus detection was conducted and plasma samples collected every other day for progesterone determination. Ovulation rates were determined by counting the number of corpora lutea on each ovary using a mid-ventral surgical approach. Intervals from sponge withdrawal to onset of estrus (h) were 44.5±4.5 (0 IU), 32.9±1.7 (250 IU), 37.8±1.1 (500 IU), 26.9±3.2 (750 IU) and 27.1±2.6 (1000 IU). Mean durations of estrus (h) were 25.0±0.6 (0 IU), 61.3±3.9 (250 IU), 12.0±4.5 (500 IU), 49.9±7.0 (750 IU) and 44.5±11.7 (1000 IU). Ovulation rates (based on number of corpora lutea) averaged 1.0±0.0, 1.3±0.3, 2.0±0.0, 5.5±0.5 and 7.0±1.2 for ewes treated with 0, 250, 500,750 and 1000 IU PMSG, respectively. Post-synchronization estrous-cycle lengths increased linearly due to PMSG treatment and were 16.5±0.5, 17.0±0.6, 18.0±0.6, 19.5±0.5 and 23.8±0.3 days for ewes treated with 0, 250, 500, 750 and 1000 IU PMSG, respectively. Plasma progesterone concentrations also showed significant treatment effects being dose dependent. Total progesterone concentrations were 15.3±2.5 (0 IU), 36.6±10.9 (250 IU), 56.1±7.7 (500 IU), 82.2±5.6 (750 IU) and 125.7±9.0 (1000 IU) (ng/ml). The results indicate the possibility to increase ovulation rates in Yankasa ewes with PMSG and to establish a direct relationship between PMSG dosage, ovulation rate and plasma progesterone concentrations.

The effect of protein intake on the onset of puberty in Bunaji and Friesian × Bunaji crossbred bulls in Nigeria

Twenty-one Bunaji (BJ) bulls and 21 Friesian x Bunaji (FRxBJ) crossbred bulls, approximately 6 mo of age were divided after weaning into two groups and fed isocaloric rations (2.40 ME Mcal/Kg/DM) containing crude protein levels of 14.45% (high protein) and 8.51% (low protein) for a period of 16 mo to determine the effect of protein intake on puberty. Animals on high protein diets ejaculated first motile spermatozoa and attained puberty at significantly (P < 0.05) earlier ages than those on low protein diets. Mean ages at puberty in mo for BJ on low and high protein diets were 15.50 +/- 0.51 and 14.82 +/- 0.68 and for FRxBJ, the ages were 17.79 +/- 0.82 and 12.94 +/- 0.60, respectively. The animals on high protein diets at point of puberty had significantly (P < 0.05) lighter body weights, smaller scrotal circumference, lower chest girth, better body condition score and better sperm quality than those on low protein. There were no significant (P > 0.05) differences in withers height or volume of semen at puberty for the two protein diets.

The effects of feed restriction and realimentation on the growth and reproductive function of Bokoloji bulls

A group of Bokoloji bulls (n=36), consisting of 18 young bulls (12 to 18 mo old) and 18 old bulls (24 to 30 mo old) were used to study the effects of feed restriction and realimentation on reproductive function. The bulls were placed either on a low (L). medium (M) or high (H) plane of nutrition during the 3 treatment periods. At the low and medium feeding levels, the animals received approximately 25 and 45%, respectively, of the intake of the bulls on the high plane diet. All the bulls were fed a low (L) plane of nutrition for 90 d in the first treatment period. The 3 treatments were designated as LL, LM and LH for the mid-period, and as LLH, LMH and LHH for the final period, according to the prescribed level of feeding. Body measurements and scrotal circumference were taken for all bulls before slaughter. A total of 18 bulls was slaughtered at the end of the mid-period, while the remaining 18 bulls were slaughtered at the end of the final period. Testicular weights as well as gonadal and epididymal sperm reserves were determined. At the end of the mid period, the bulls on a high plane of nutrition had significantly (P<0.05) higher live weights and chest girths than bulls on the medium and low planes of nutrition. Gonadal sperm/spermatid reserves of 5.2 x 10(9) and epididymal sperm reserves of 2.4 x 10(9) in bulls on the high plane of nutrition were significantly (P<0.05) higher than the sperm reserves for the bulls on either the low or the medium plane of nutrition. At the end of the final period, ho significant differences existed among the LHH, LMH and LLH treatments in liveweight, chest girth, scrotal circumference and sperm reserves (P>0.05). It is concluded that bulls which have undergone feed restriction for 90 d are capable of regaining their body growth and reproductive function if such bulls are placed on an adequate plane of nutrition.

Effects of Trypanosoma vivax on pregnancy of Yankasa sheep and the results of homidium chloride chemotherapy

Three groups of pregnant Yankasa ewes, made up of six ewes in each group were assigned at random to first, second and third trimester of pregnancy studies. The ewes were experimentally infected with T. vivax to study the effects of the infection on pregnancy and the results of Novidium Chemotherapy. Three pregnant uninfected ewes served as controls. Fourteen days post infection, the ewes in each trimester study, were paired by weight and assigned to two groups of three ewes each. One group was treated with Novidium while the other group remained untreated. Of the three ewes in each group, one ewe was killed humanely at 21 days post infection and another at the end of the trimester period. In the first trimester, a ewe with partial fetal resorption was observed among the untreated ewes. Fetal death in-utero and expulsion of an autolyzed fetus was observed among the treated ewes. In the second trimester, abortion and almost complete fetal resorption were observed among the untreated ewes. Fetal death in-utero and expulsion of an autolyzed fetus was observed among the treated ewes. In the third trimester, abortions were observed among the untreated ewes. Abortion of a live fetus and a case of dystocia were observed among the treated ewes. Ewes in the second and third trimesters of pregnancy were more susceptible to the infection, with ewes in the third trimester being most susceptible, as measured by the number of abortions and death of ewes. Fetuses from the untreated ewes in the three trimesters of pregnancy were lower in body weights, than the fetuses from the treated ewes. The uninfected control ewes carried the pregnancies to term. Novidium chemotherapy at 14 days post infection was not beneficial in ameliorating the pathogenicity of T. vivax infection on pregnancy in Yankasa ewes. T. vivax infection of only 14 days was enough to cause irreversible pathology in Yankasa fetuses evidenced by death of fetuses in-utero, dystocia and abortions irrespective of Novidium chemotherapy.

Peripheral plasma levels of progesterone in Nigerian Zebu cows following synchronization of oestrus with Prostaglandin F2 alpha analogue (dinoprost tromethamine)

Abstract The luteolytic effect of Prostaglandin F 2 alpha (PGF 2α ) was studied by measuring plasma progesterone levels in 30 Bunaji and Sokoto Gudali (Zebu) cows. Two intramuscular (i.m.) injections each of 25 mg of the analogue (Dinoprost tremethamine) were given 11 days apart and blood samples for plasma were collected daily beginning from first injection up to 7 days after the second injection of PGF 2α or up to 30 days after artificial insemination (A.I). Mean progesterone levels on the day of first injection were 4·1 + 0·3 and 0·6 ± 0·2 nanograms per millilitre (ng/ml) for cows in luteal and follicular phases respectively. Luteolysis was complete within 24–48 h of injection as confirmed by plasma progesterone levels. Cows in luteal and follicular phases showed standing oestrus 75·1 ± 2·1 h and 55·2 ± 12·2 h after PGF 2α injection. Partial or incomplete luteolysis were also observed in 2 cows. Cows showing standing oestrus after a second injection of PGF 2α were artificially inseminated 12 h after the onset of oestrus. Six out of 12 cows (50%) were diagnosed pregnant by rectal palpation at 60 days post-insemination. Plasma progesterone levels in pregnant cows remained elevated (2–15 ng/ml) and did not drop below 2·0 ng/ml following attainment of peak levels. Appreciable levels (1.0 ng/ml) of progesterone were first detected 5–6 days postinsemination in inseminated cows. Of those that were later diagnosed non-pregnant, however, there was a cyclic progesterone pattern which culminated in complete luteolysis about 18 days after the infertile insemination. The results indicate that intramuscular administration of 25 mg of PGF 2α per cow during the luteal phase of the oestrous cycle of Zebu cows shortens the secretory lifespan of cyclic corpus luteum, and that plasma progesterone assays may be valuable in assessing the reproductive performance of Zebu cows indigenous to Nigeria.

Plasma progesterone levels during oestrous cycle and their relationship with the ovulation rate in Red Sokoto (maradi) goats

Twenty-five 2-3-year-old cycling does weighing 17-25 kg were obtained from semi-nomadic farmers and managed under controlled conditions while simulating the traditional management system. Oestrus was synchronized using progestogen impregnated vaginal pessaries. Blood samples were collected daily for progesterone assay from the day of pessary withdrawal up to one complete oestrous cycle. Oestrus was checked twice daily using vasectomized bucks. Ovulation rate was determined by direct observation of the ovaries following laparotomy on day 5-7 of the oestrous cycle. Following oestrus synchronization, mean ovulation rate was 1.68 +/- 0.13. Mean oestrous cycle length and duration of oestrus were 21.30 +/- 0.28 days and 21.37 +/- 0.24 hours respectively. Plasma progesterone concentrations ranged from non-detectable levels on the day of oestrus to 5.2 +/- 0.28 ng ml at mid-cycle. The duration of elevated progesterone level (greater than 2 ng/ml) was about 12 days. The peak progesterone values did not differ between animals with different ovulation rates. However, the plasma progesterone concentration during the early cycle (days 0-6) was significantly lower in the single ovulators compared with others. There were no major differences in plasma progesterone levels during the oestrous cycle of Red Sokoto does with different ovulation rates.