[en] Animal productivity may be measured among others, in terms of two important physiological processes of reproduction and growth each of which involves a number of integrated disciplines. Both physiological processes are controlled by interactions of genotype and environment. Reproduction essentially involves complex physiological processes controlled by secretions of endocrine glands known as hormones. On the other hand growth is determined largely by availabilty of essential nutrients. In order to achieve good reproductive and growth rates adequate and constant nutrition for livestock include pasture, cereals, tubers and their by-products as well as industrial by-products. While reproduction is essential to provide the required number and replacement of livestock, growth guarantees availability of meat. Another aspect of livestock production is disease control. An animal needs a good health to adequately express its genetic make up and utilize available nutrition. Research in animal production is aimed at improving all aspects of productivity of livestock which include reproduction, growth, milk production, egg production, good semen etc. of livestock. In order to achieve this an understanding of the biochemical and physiological processes occurring in the animal itself, and in the feedstuff fed to the animal as well as the aetiology and control of diseases affecting the animal among other factors, is desirable. A number of methods of investigation have evolved with time. These include colorimetry, spectrophotometry, chromatography, microscopy and raidoisotopic tracer methods. While most of these methods are cumbersome and use equipment with low precision, radioisotopic tracer methods utilize equipment with relatively high precision

[en] The traditional systems of management of reproduction of cattle indigenous to West Africa and various improvement strategies employed are reviewed. Strategies have been evolved to facilitate early attainment of puberty and first conception, reduce inter-calving intervals and control oestrous and the oestrous cycle. Among the strategies and techniques used to achieve various degrees of improvement in these reproductive parameters are improved nutrition, diagnosis and control of diseases, determination of hormonal profiles and semen characteristics, and administration of drugs as well as strategic management practices. More investigations are required for a full understanding of the factors influencing reproductive performance and identification of the most appropriate management practices necessary to improve the reproductive efficiency of cattle indigenous to West Africa. (author). 97 refs, 4 figs, 10 tabs

[en] Experiments were carried out in Yankasa sheep to study the efficacy of progesterone for oestrous synchronization and the effect of various gonadotrophin treatments (pregnant mare serum gonadotrophin (PMSG), human chorionic gonadotrophin (HCG) and gonadotrophin releasing hormone (GnRH)) on ovulation rates and litter size, and to elucidate responses by monitoring progesterone concentration. Preliminary studies showed normal progesterone profiles during the cycle, and a mean ovulation rate and litter size of 1.36 ± 0.34 and 1.23 respectively. Following synchronization with progesterone pessaries, PMSG dosage influenced ovulation rates. When 500 IU PMSG was given to ewes, HCG injection had an additive effect of increasing ovulation rate. Plasma progesterone concentrations showed significant treatment effects, being increased in relation to an increase in ovulation rates. Ovulation in Yankasa ewes occurred between 30-32 hours from onset of oestrus. In a fertility trial, mean ovulation rates and corresponding litter size were 2.1 versus 1.8 and 1.5 versus 1.2 for PMSG treated and untreated ewes respectively. 24 refs, 8 figs, 5 tabs

[en] Over 90% of the population of zebu cattle in Nigeria belong to smallholder agro-pastoral farmers who adopt relatively inefficient production systems (Otchere and Nuru, 1988). Shortage of feed and poor quality of tropical pastures are a major constraint to livestock development, and this is often characterized by extended post-partum anoestrous periods. Biostimulation via pheromones can play an important role in mammalian behaviour and reproductive process. A total of 51 pleuriparous post-partum cows belonging to agro pastoralists were involved in a 2 x 2 factorial experiment for a period of 180 d. The cows were assigned randomly at calving to four treatments: (1) grazing only (no supplementation) and exposure to bull (NSBE); (2) grazing only (no supplementation) and no exposure to bull (NSNE); (3) grazing plus feed supplementation (each cow received 600 g of 20.8% crude protein of whole cottonseed supplement per day) and exposure to bull (FSBE); (4) grazing plus feed supplementation and no exposure to bull (FSNE). Post-partum cows were observed visually for the standard signs of oestrus (standing to be mounted) twice daily between 07:30 and 08:30h and 17:30 and 18:30h by experienced herdsmen and technicians. Cows in oestrus in the non-exposed group were taken to the bull for 24h for mating. Once weekly, whole milk samples were taken from cows 7-180 d post-partum for determination of progesterone concentrations using RIA kits. Cows with an increase in milk progesterone (P₄) concentration of <1 ng/mL from the weekly milk samples were used to analyse the number of days from calving to the time of resumption of ovarian activity. The interval from calving to resumption of post-partum ovarian activity for the feed supplemented (FS) cows was 107 d; earlier than the 136 d for the non-supplemented (NS) cows (P < 0.05; Table I). Similarly, cows exposed to bulls (BE) resumed post-partum ovarian activity earlier than the non-exposed (NE) cows with a difference of 16 d. Average daily gains for the FS cows were significantly higher than the NS cows. Resumption of ovarian activity for FSBE cows was 95 d, earlier than the 119 d for the FSNE cows (P < 0.05). The intervals to onset of postpartum ovarian activity were 24, 33 and 39 d significantly earlier in the FSBE cows than the FSNE, NSBE and NSNE cows (P < 0.05). The intervals to resumption of cyclic ovarian activity were 9 and 15 d earlier in the FSNE cows than the NSBE and NSNE cows (P< 0.05; Table I). At 120 d post-partum, the proportion of cows that had resumed ovarian activity was 75% for the FSBE cows, which was higher than the values of 42%, 23% and 33% for the NSBE, NSNE and FSNE cows, respectively (P < 0.05). In addition, by 120 d, the proportion of cows with ovarian cyclicity for NSBE cows was 42%; higher than the value of 23% for the NSNE cows (P < 0.05). By 150 d post-partum, 100% and 92% of the cows in the supplemented groups (FSBE and FSNE) had resumed cyclic ovarian activity compared with 75% and 69% for the unsupplemented cows (NSBE and NSNE; P < 0.05). This study indicates that supplementation and exposure to bulls can shorten the length of postpartum anoestrus. This agrees with previous studies which have reported that (Butler and Smith, 1989) and exposure of post-partum cows to bulls (Bolanos et al., 1997) hastened the onset of ovarian cyclicity after calving. The economic benefits of using exposure to bulls and supplementation to enhance early resumption of post-partum ovarian activity of cattle may serve as a management tool in livestock production. (author)

[en] The effects of management on the productivity of Bunaji cattle were investigated on 6 farms using 38 post-partum cows and 8 heifers. General information obtained on management of the farms indicated differences in managements practices between farms. The screening of the animals in the various farms for blood and endo-parasites showed that some of the farms had problems of helminthiasis and fascioliasis. Uterine involution was complete within 25 days of calving in all post-partum cows. Intervals from calving to ovulation and conception were different between farms. The conception rates for all farms over a period of 730 days ranged from 60 to 100%. A higher percentage of heifers on farm A reached puberty at an earlier age than those in farm B. It was concluded that management affects reproductive performance and thus productivity of Bunaji cattle, with nutrition and disease being the major contributing factors. (author). 10 refs, 7 tabs

[en] The effects of forage legume lablab (Lablab purpureus) as a supplement for Bunaji cows was investigated both on-station and on-farm. The results of the on-farm trial involving five herds in each of two villages (control and supplemented) showed that supplementation with 3 kg of lablab increased milk off-take significantly (P<0.001) (1.27±0.09 vs. 0.71±0.1 kg per cow/day for supplemented and non-supplemented cows, respectively). Cows in the supplemented group showed a higher gain in body weight compared to non-supplemented animals (411±1.4 vs. 127±1.8 g/day respectively). They also showed a higher (P<0.001) body condition score than those in the non-supplemented group (3.5-4.5 vs. 2.0-3.5). Overall mean weight gain for calves was however, similar for both supplemented and non-supplemented groups (428±5.3 vs. 428±1.5 g/day). Supplementation of suckling Bunaji cows with lablab improved the performance of the animals and the income of the farmers. (author)