D.I.K. Osori

Effect of level of nutrition on onset of puberty and conception rates of zebu heifers

Sixty zebu heifers were divided into three equal groups and reared on isocaloric diets but on different levels of protein. The protein levels were 19.17% (high), 13.37% (medium; NRC recommendations) and 8.3% (low). All animals were examined weekly per rectum for the presence of follicles and corpora lutea and also checked daily for standing heat. The presence of a mature corpus luteum was considered to indicate the attainment of puberty. Body weight and pelvic dimensions were taken at biweekly intervals. Intact bulls were introduced to heifers after they reached puberty and once they reached 200 kg live weight. Pregnancy diagnosis was carried out at 60, 90 and 120 days following introduction of bulls. Mean age at puberty for heifers in the high protein group (570.4 days), medium protein group (640.8 days) and low protein group (704.2 days) differed significantly (P<0.05). body weight at puberty for heifers in the high, medium and low protein groups was 207.1, 187.0 and 161.7 kg, respectively (P<0.05). Pelvic size at puberty was not influenced by the nutritional level. Conception rates of heifers in the three groups were influenced by level of nutrition. Pregnancy rates for the high protein group (58.8%), medium protein group (27.8%), and low protein group (16.7%) by 90-day post-breeding period were significantly different (P<0.05), but body weight at conception between the groups did not differ significantly. The results show that increasing the protein level in the diet is a means of improving the reproductive performance of zebu cattle.

Bovine besnoitiosis and its effect on the male reproductive system

Besnoitia besnoiti and several species of the genus have been reported in a variety of domestic and wild animals in many parts of the world (1, 2, 3, 4, 5). Cutaneous besnoitiosis in cattle has been described as a serious skin condition characterized by painful swellings, alopecia and thickening of the skin (6). It is a chronic, debilitating and occasionally fatal disease with both cutaneous and systemic manifestations (6, 7, 8). Besnoitia cysts and lesions have been observed in the testes, epididymes and blood vessels of bulls (9). The possibility of abortion in cows and sterility in bulls with besnoitiosis has been reported (6). Spontaneous clinical besnoitiosis in cattle with accompanying systemic manifestations has not been fully documented, and the effect of scrotal besnoitiosis on spermatogenesis in bulls has not been previously reported in Nigeria. Case report : Outbreaks of babesiosis, heartwater and suspected cutaneous besnoitiosis were observed in a government farm in the Kano State of Nigeria in March, 1979. The cattle population was over 1500, consisting of exotic (Bos taurus ) and indigenous (Bos indicus ) breeds and their crosses. Clinical Examination : All stages of clinical besnoitiosis were initially observed in 14 bulls and 1 cow in a period of 4 months. The farm was visited bi-weekly for 1 year, during which time 58 bulls and 2 cows showed the lesions. Most of the animals affected with this disease were 3-way crosses of Australian Draughtmaster x Rahaji x Niger Azwak (DM x Rh x AZ). Table 1 summarises the distribution of clinicial cases of besnoitiosis.

Effects of experimental Trypanosoma vivax infection on first-, second-, and third-trimester pregnancy in heifers.

The effects of Trypanosoma vivax on pregnancy were studied in 18 heifers. The heifers were bred by a proven bull and divided into three groups of six heifers each. In the first group, four heifers were infected with T . vivax on Day 60 (first trimester) of pregnancy; two other pregnant heifers were uninfected controls. The second and third groups were similarly infected in the fourth (second trimester) and seventh (third trimester) month of pregnancy. One infected heifer in the first-trimester group aborted 39 days postinfection (p.i.); the remaining three had relatively normal gestation and parturition. In the second-trimester group, the pregnancies were carried to term with normal deliveries. In the third-trimester group, three infected heifers (75%) had premature deliveries while the fourth died about three hours after the full-term calf was pulled out. All of the control heifers had normal gestation and parturition. No gross abnormalities were seen in the placentae of the infected heifers, but histological sections of the heifers infected in the third trimester of pregnancy revealed more mononuclear cells than in those of the uninfected controls. Postmortem examination of the dead premature calves showed lymphadenopathy, splenomegaly, serous atrophy of perirenal and pelvic fat, epicardial petechiae, and blood-tinged peritoneal and pericardial fluids. Histologically, there were slight myocardial haemorrhages and edema. T. vivax was recovered from the blood of one of the premature calves. Both birth weights and PCV were affected by the experimental maternal infection in the first- and third-trimester calves. The birth weights and PCV of calves of infected dams were lower than those for the calves of the control heifers. This work therefore demonstrates transplacental transmission of T. vivax in heifers.

Effects of experimental Trypanosoma vivax on fertility of heifers

Abstract Six heifers were used in a series of experiments to study the effects of experimental Trypanosoma vivax infection on bovine reproduction. Four three-year-old Zebu heifers were intravenously inoculated with T. vivax-strain Y58 — on days 14 and 16 of their estrous cycle and two control heifers in the same phase of estrus were not infected. All the heifers were bred in the research pens with a proven bull. The four infected heifers were bred at the first wave of parasitemia and the onset of pyrexia which characterised the infection. All the heifers were examined rectally 40 days after breeding. The four infected heifers were not pregnant but the two controls were. The infected heifers later became anestrous during the experimental period of more than five months. It is concluded that trypanosomiasis may contribute to high infertility rates in cattle kept in endemic areas.

Effects of rectal and ambient temperatures and humidity on conception rates.

One hundred and thirteen inseminations were performed for which rectal temperatures were taken at the time of inseminations. Climatological factors were also recorded daily. Pregnancy diagnosis by rectal palpation was carried out 3 months post-insemination. Pregnancy rates for all services were related to selected climatological measurements and rectal temperatures. The results obtained indicate that elevated rectal temperature, mean maximum and mean minimum temperatures and relative humidity were detrimental to conception. The effect of the climatological factor on conception is compounded by feed scarcity during the dry periods of the year.

Determination of onset of puberty in Zebu bulls under tropical conditions of northern Nigeria

Age at puberty and related phenomena were investigated in White Fulani (Bunaji - WF), Sokoto Gudali (SG) and Friesian X Bunaji (FRXWF) Zebu bulls from 28 weeks to 72 weeks of age. Pubertal traits studied included body weight, heart girth, scrotal circumference and sperm production. Puberty was defined as the age at which an ejaculated semen contained at least 50 x 10(6) spermatozoa with a minimum of 10% motility. Age at puberty was 66.89 +/- 1.0, 73.4 +/- 2.2 and 62.4 +/- 10.7 weeks for WF, SG and FRXWF bulls respectively. The Bunaji bulls were significantly younger than the Sokoto Gudali bulls at production of first motile sperm cell and also at puberty (P<0.01). The SG bulls were significantly heavier (P<0.01) and had larger heart girth (P<0.05) than the FRxWF at production of first motile sperm cells. Body weight and heart girth for all the breeds were not different at puberty (P>0.1). Scrotal circumference of the bulls between the breeds at production of first motile sperm cells and at puberty, did not differ (P 0.>1), despite the variations in age, weight and heart girth at production of first motile sperm cell and at puberty. It is concluded from the data obtained that the indigenous breeds of bulls (Bos indicus ) seem to attain puberty later than exotic breeds (Bos taurus ). The inter-play of genetic, nutritional and environmental factors as a contribution to this delay in attainment of puberty could not be ruled out.

Perineal hypospadias in two related bull calves, a case report

Hypospadias in bulls and other domestic animals has not been reported in Nigeria. Within the past four years since starting a survey of reproductive problems in bulls and small ruminants, five cases of hypospadias have been observed: 4 in calves and 1 in a goat. The following is a report of 2 of the affected calves.

Bacteriological investigation of the postpartum uterus: Relationship to involution and histopathological findings.

A bacteriological investigation of the postpartum uteri of suckled and nonsuckled Bunaji (White Fulani) cows was undertaken to determine the microflora, the effect of suckling on the flora and the influence of the flora on uterine involution and histopathology. Uterine contamination by bacteria was highest between days 10 and 21 postpartum with Staphylococcus aureus being the commonest organism isolated. There was no consistent isolation of one type of bacterial organism from a cow throughout the sampling period. Suckling did not affect the incidence of uterine contamination by bacteria. Foci of leucocytes (mainly lymphocytes) were found in uterine sections in an increasing frequency with days postpartum. Bacteria were isolated from only 3 of the 12 uteri that had the leucocytic foci. Uterine involution was normal and complete by 25 days after calving irrespective of the presence or absence of bacteria or leucocytic foci. We concluded that postpartum uterine contamination by bacteria was not influenced by suckling and that puerperal uterine contamination by bacteria did not interfere with the normal process and duration of uterine involution.

Effects of the reproductive status in Zebu heifers on the immunoglobulin M and G levels in bovine Trypanosoma vivax infection

Immunoglobulin M and G levels in bovine Trypanosoma vivax infection were compared in non-pregnant, first, second and third trimester pregnant heifers. All the infected heifers showed a significant rise in IgM levels when compared to the non-infected controls. 7–8 fold increases were recorded. There were however differences in the rate of increases and ability to maintain peak level response (P <0.01) between the groups. Infected pregnant heifers in the first and second trimester responded better than infected non-pregnant and infected heifers in the third trimester pregnancy. In all the groups, the differences between the infected and control heifers were highly significant (P <0.001). The IgG levels showed a similar pattern of increases in infected heifers though response was gradual. In the different groups 1.4–2.5-fold increases were recorded. These were significantly different from levels in the control (P <0.01). Again, pregnant heifers responded better than non-pregnant heifers except those in the third trimester pregnancy. The results correlated with the observation that given the same conditions, clinical manifestation of T. vivax infection is more severe in non-pregnant than in pregnant heifers except those in advanced pregnancy.

Bovine streptothricosis and reproduction in Northern Nigeria: a case study.

A group of cows, which were naturally infected with streptothricosis, was observed for 17 months. The genitalia were examined per rectum, at least twice monthly to determine the ovarian activity. During the period of observation, 83.3% of the lightly affected cows were pregnant or had calves, while only 33.3% of the moderately/severely affected cows had calves. It is suggested that streptothricosis, like any other debilitating disease, affects reproductive performance, and in the case of severe, localized, perineal infection, the disease results in mechanical interference with mating.