J. Kumi-Diaka

The effect of Trypanosoma vivax and Trypanosoma congolense infections on the reaction time and semen characteristics in the Zebu bull

Abstract The effect of trypanosomiasis on reaction time and semen characteristics of 24 Zebu bulls was studied. Eight of the bulls were infected with T. vivax , another eight with T. congolense and the remaining eight bulls served as controls. The preinfection mean value of the rectal temperature was 101.0 °F, and this rose to a mean of between 104·5 and 105·5 °F in the infected animals. Concurrently the latter animals exhibited signs of anaemia shown by pale mucous membranes and decreased PCV, weight loss, lethargy, weakness and dullness. The reaction time of semen collection significantly increased from a pre-infection mean value of 24·3–60·13 seconds to a mean of 14·25–267·25 seconds within 12 weeks post-infection. Semen characteristics deteriorated progressively within the same period in the infected bulls. There were highly significant and drastic decreases in sperm concentration and volume of semen and increases in abnormal sperm cells. By the sixth week, the 16 infected bulls were unfit for breeding because of very poor semen characteristics. Deterioration continued to the end of the investigation. The present results indicate that T. congolense appeared more virulent and devastating in its effect on the reaction time (ejaculation time) and on the destruction of germinal epithelium which resulted in poor semen quality. This is of particular significance to livestock farmers in trypanosome endemic regions, the practical implication being infertility in infected bulls.

Pathological changes in male genitalia of cattle infected with Trypanosoma vivax and Trypanosoma congolense.

Samples for histological studies were taken from the genitalia of 14 bulls (five infected with Trypanosoma vivax, five with T. congolense and four uninfected control animals), slaughtered 12, 22 or 30 weeks post-infection. Infection with Y58 strain of T. vivax and strain 2295 of T. congolense caused various grades of lesions in the male reproductive organs, especially the testes and epididymides. T. congolense produced more severe degenerative changes than T. vivax. It is concluded that in long-standing cases, the result of trypanosome infection is either serious infertility or even sterility.

Comparative haematological changes following Trypanosoma vivax and T. congolense infections in Zebu bulls

A comparative study of haematological changes subsequent to Trypanosoma vivax and Trypanosoma congolense infections was carried out using 24 Zebu bulls during a period of 12 weeks. Eight bulls were infected with T. vivax, another eight with T. congolense and eight served as controls. Infected bulls developed chronic trypanosomiasis which was characterized by many clinical manifestations including intermittent pyrexia. Elevated rectal temperatures of up to 105 and 106 degrees F were recorded, respectively, in all bulls infected with T. vivax or T. congolense. Mean parasitaemia was higher and more chronic in T. congolense-infected bulls and ranged between means of 0 and 3.06 in all infected bulls. There was a slight and transient drop in packed cell volume (PCV) of T. vivax-infected bulls as against a marked and more chronic drop in T. congolense-infected bulls. Mean PCV of T. vivax- and T. congolense-infected bulls and controls ranged between 28 and 38, 17 and 38, and 31 and 38%, respectively. Haemoglobin (Hb) concentrations also decreased in infected bulls. The decrease was greater and more chronic in the T. congolense-infected bulls. Values ranged between means of 10.47 and 13.84, 5.44 and 14.16, and 10.24 and 14.12 g dl-1 in T. vivax- and T. congolense-infected and control bulls, respectively. Total plasma proteins also decreased in infected bulls; this was more marked in the T. congolense-infected group. Values for T. vivax-infected, T. congolense-infected and control bulls ranged between means of 7.66 and 8.99, 6.26 and 8.81, and 7.94 and 8.78 g dl-1, respectively.2+ that the indigenous T. vivax strains are more

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).

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. n nBulls 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. n nThe 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.

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.

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.

Seasonal and monthly variations in the incidence of morphological abnormalities in bovine spermatozoa in Shika, Zaria, Northern Nigeria

Morphological abnormalities of spermatozoa were evaluated in ejaculates of 27 healthy bulls aged between one and a half and three and a half years from January to December of 1982. The year was divided into three seasons: (1) January-April (partly harmattan, dry and hot), (2) May-August (rainy), and (3) September-December (dry and partly harmattan). All the bulls showed seasonal variations in the incidence of sperm-head abnormalities, detached-heads, proximal cytoplasmic droplets and total morphological abnormalities. n nThe means for total morphological abnormalities of the spermatozoa were 21.5%, 10.6% and 11.3% for seasons 1, 2 and 3, respectively (P<0.01). There were also monthly variations in the incidence of morphological abnormalities of the spermatozoa. The monthly means for total morphological abnormalities of the spermatozoa ranged between 23.74% in March and 4.8% in September (P<0.001). n nThe results indicated that there were significant seasonal and monthly variations in morphological abnormalities of spermatozoa and that the bulls may be most fertile and best used during the rainy season.

Elevation of morphological abnormalities of spermatozoa in the semen of Zebu bulls consequent to Trypanosoma vivax and Trypanosoma congolense infections

Twenty-four Zebu bulls were used in a 12-wk long study. Eight bulls were infected with T. vivax , eight others with T. congolense and eight bulls served as controls. All the infected bulls developed chronic trypanosomiasis. Mean percentage base-line values prior to infection for acrosomal, sperm-head, detached heads, proximal cytoplasmic droplets, distal cytoplasmic droplets, sperm-tail, midpiece and total sperm morphological abnormalities ranged between 0.1+/-0.1 for acrosomal and 8.7+/-3.4 for total morphological abnormalities in the semen of the bulls. These values were very low and within the range of those for fertile bulls. Following infection, there was a progressive increase in the mean values of all the abnormalities. Peak percentage mean values recorded for total sperm morphological abnormalities in the course of the investigation in the bulls infected with T. vivax and T. congolense and in the controls were 95+/-7.2, 100+/-0 and 7.9+/-5.0, respectively. Mean percentage values throughout the duration of the investigation for control bulls were low and within the normal range for fertile bulls. These values differed (P<0.001) from the elevated values of the infected bulls. The results indicate that trypanosomiasis due to either T. vivax or T. congolense infections can cause a marked increase in morphological abnormalities of spermatozoa which can, in turn reduce the fertility of breeding bulls.

Effect of chemotherapy on elevated ejaculation time and deteriorated semen characteristics consequent to bovine trypanosomiasis

The effect of the trypanocidal drug Novidium on elevated ejaculation time and deteriorated semen characteristics was studied in Zebu cattle infected with T. vivax and T. congolense. Two groups, comprising six bulls per group, were infected with Trypanosoma vivax or Trypanosoma congolense while three bulls served as controls. Chemotherapy was carried out 12 weeks post-infection on three bulls from each group, leaving three bulls untreated while three bulls served as uninfected controls. Blood samples from treated bulls were all negative for trypanosomes 3 days post-chemotherapy. The animals also had normal body temperature. As the study progressed, clinical signs associated with trypanosomiasis, such as anaemia and cachexia, disappeared gradually in treated bulls. There was some improvement in semen characteristics of some of the bulls at 10 weeks post-chemotherapy with Novidium. However, all bulls infected with T. vivax or T. congolense irrespective of Novidium chemotherapy still had poor semen characteristics manifested by all or some of the following: decreased volume of semen, oligospermia, azoospermia and elevated incidence of spermatozoa morphological abnormalities. They were thus unsuitable for breeding.