EFFECTS OF BOVINE SOMATOTROPIN ON CHANGES IN UDDER DIMENSIONS AFTER CESSATION OF MILKING IN WEST AFRICAN DWARF GOATS

A study was conducted to determine the effects of bovine somatotropin (bST) on changes in udder dimensions (UD) including udder length (UL), udder width (UW), udder circumference (UC) and distance between teats (DT) after cessation of milking in twelve West African Dwarf (WAD) goats, which were divided equally into four treatment groups, each comprising three does. The first group (control, T0) received no bST while the other groups received bST (T1, 20 mg; T2, 40 mg; T3, 60 mg) injected at 2-week intervals commencing from the 5th week postpartum for 8 weeks. Does were milked twice daily (7:30 am and 7:30 pm). Twenty four hours after the twelfth week, measurement of UD commenced for 35 days. The results revealed that UL, UW, UC and DT were significantly (p<0.05) influenced by bST dose, day after cessation of milking and parity and the UD increased with increased doses of bST.  There was maximal distension of udder by day 3 to 5 in treated goats than in the control which was on day 2 before declining progressively up to 35th day after cessation of milking. This showed a greater capacity to retain secretions as explained by the larger udder size. Therefore, the administration of bST to WAD goats during lactation extended its effects on mammary glands after cessation of milking and slowed down the rate of udder regression, thus, enabling the potential of bST treated goats for greater milk synthesis in the next lactation cycle. &nbsp

EFFECTS OF BOVINE SOMATOTROPIN ON THE PATTERN OF MILK YIELD WITHIN AND BETWEEN INJECTION INTERVALS IN WEST AFRICAN DWARF GOATS

Twenty-four West African Dwarf (WAD) goats were used to study the pattern of milk yield response torecombinant bovine somatotropin (rbST) administered in a sustained-delivery vehicle. The goats weredivided equally into four treatment groups, each comprising of six does. The first group (control, T0)received no rbST while the other groups received rbST (T1, 20 mg; T2, 40 mg; T3, 60 mg) injected at 2-week intervals commencing from the 7th week postpartum for 6 weeks. Pattern of milk yield responseto rbST was significantly (p<0.05) influenced by rbST dose, day from rbST treatment, order of rbSTtreatment and parity. Milk yield of treated goats increased from day 1 of treatment, peaked betweenday 5 and day 8 after treatment and progressively decreased until day 14 of treatment but that of thecontrol decreased progressively from day 1 till day 14 of treatment. The mean relative response ofDMY to rbST treatment for T1, T2 and T3 exceeded T0 by 50.36, 68.00 and 71.16 % respectively andsignificantly affected the shape of the lactation curve, thus, improving persistency of lactation. Thepatterns of DMY for T1, T2 and T3 were well-fitted by the Wood’s equations: Y = 16.628n1.728e-0.439n (R2= 63.1), Y = 25.198n0.836e-0.239n (R2 = 75.6) and Y = 0.008n9.081e-1.352n (R2 = 42.3) respectively. Theadministration of 40 mg dose of rbST appears to elicit DMY response that favoured milk yield persistency.But since highest DMY was observed with 60 mg dose of rbST, estimation of optimal dose thatwould elicit maximum DMY response may be required in order to validate the statement. Our findingssuggest that rbST administration to WAD goats after peak of lactation can enhance milk yield, galactopoiesisand persistency of lactation indicating higher milk yield in extended lactation

ESTIMATION OF OPTIMAL DOSE OF BOVINE SOMATOTROPIN FOR MAXIMUM MILK YIELD RESPONSE IN WEST AFRICAN DWARF GOATS

Optimal dose of bovine somatotropin (bST) in a sustained-delivery vehicle required for maximum milkyield response was estimated in twenty-four lactating West African Dwarf (WAD) goats in three 14-dayperiods using quadratic equation. The goats were divided equally into four treatment groups, eachcomprising six does. The first group (control, T0) received no bST while the other groups received bST(T1, 20 mg; T2, 40 mg; T3, 60 mg) injected at 2-week intervals commencing from the 7th week postpartumfor 6 weeks. Does were milked twice daily (7:30 am and 7:30 pm) and milk yield recorded daily.Daily milk yield response (DMY) to bST was significantly (p<0.001) influenced by bST dose, day frombST treatment and parity during the 2nd period of bST treatment but only bST dose and parity significantlyinfluenced (p<0.001) DMY during the 1st and 3rd periods of bST treatment. The mean relativeresponse of DMY of bST-treated goats exceeded the control by 48 – 78 % in the entire periods of bSTadministration. Highest predicted response of 80.5 % in the 3rd period and lowest response of 66.2 %in the 1st period of bST treatment (when compared to the control) were observed, thus indicating thatbST positively affected the shape of the lactation curve for possible higher yield in extended lactation.Although, the trend of observed and predicted optimal doses of bST needed for maximum DMY werewell-fitted by the Quadratic equation during the three periods of bST treatment, it varied inconsistentlywith periods of bST treatment (stages of lactation). Therefore, the uniform optimal dose of 50.71 mgper 2 weeks estimated by quadratic equations; Y = 141.318 + 4.097X – 0.041X2, R2 = 99.90), Y =100.912 + 2.926X – 0.030X2, R2 = 99.49 and Y = 5935.420 + 172.071X – 1.735X2, R2 = 99.49 andneeded for maximum DMY of 242.86 ml, relative DMY of 74 % and cumulative milk yield response of10214.29 ml respectively over the entire periods could be adopted in West African Dwarf goats in orderto reduce the complexity of differential injections administered with respect to stages of lactation

EFFECTS OF FEED RESTRICTION AND REALIMENTATION ON PERFORMANCE AND NITROGEN UTILISATION IN GROWING WEST AFRICAN DWARF RAMS

The effects of feed restriction on the performance of growing West African Dwarf sheep were determined in twenty four (24) growing West African dwarf (WAD) rams with average weight of 8.9 ± 0.59kg. The twenty-four WAD rams were allotted to three treatments of eight rams per treatment and balanced for weight in a Completely Randomized Design. Animals in group C which represents the control were fed with dried Panicum maximum ad libitum and concentrate supplement while group two (R1) and group three (R2) were fed with P. maximum without concentrate supplementation for one and two months, respectively. Thereafter, two months of realimentation followed the restriction. Data were taken on the feed intake, weight gain and digestibility. Results obtained on average daily gain showed significant difference (P < 0.05) whereby sheep on R2 group recorded the lowest value (50.7g/day) during restriction. Digestible organic matter intake (g/Kg 0.75 d-1) for sheep on the C group was significantly (P < 0.05) higher than R1 group, but not significantly (P > 0.05) different from R2 group. The Crude protein intake was highest in the control (49.9g/day). Rumen amino acid of the control animals (4.1) was significantly (P < 0.05) higher than R1 (2.1) and R2 (3.5) groups. Nitrogen intake (g/day) was significant and higher in the C group (8.0) compared to the two restricted groups R1 and R2. During realimentation period, average daily weight gain (g/day) was highest (P < 0.05) for animals in the control (57.5) and least in R2 (34.5). The feed conversion ratio ranged from 8.3 (C) to 14.3 (R2) while the total weight gain (kg) ranged from 2.1 (R2) to 3.5 (C). Similarly, the CP intake (g/day) was higher in the control group compared to those in R1 and R2 groups. However, the dietary amino acid recorded in R2 differ significantly (P < 0.05) from R1 and C groups. During the realimentation period, nitrogen intake for rams in R1 (8.8g/day) and R2 (10.1g/day) groups doubled the values obtained during the restriction period. It was concluded that rams should be restricted for one month because they gained more weight than those restricted for two months.Â

Leveraging Available Resources and Stakeholder Involvement for Improved Productivity of African Livestock in the Era of Genomic Breeding

The African continent is home to diverse populations of livestock breeds adapted to harsh environmental conditions with more than 70% under traditional systems of management. Animal productivity is less than optimal in most cases and is faced with numerous challenges including limited access to adequate nutrition and disease management, poor institutional capacities and lack of adequate government policies and funding to develop the livestock sector. Africa is home to about 1.3 billion people and with increasing demand for animal proteins by an ever growing human population, the current state of livestock productivity creates a significant yield gap for animal products. Although a greater section of the population, especially those living in rural areas depend largely on livestock for their livelihoods; the potential of the sector remains underutilized and therefore unable to contribute significantly to economic development and social wellbeing of the people. With current advances in livestock management practices, breeding technologies and health management, and with inclusion of all stakeholders, African livestock populations can be sustainably developed to close the animal protein gap that exists in the continent. In particular, advances in gene technologies, and application of genomic breeding in many Western countries has resulted in tremendous gains in traits like milk production with the potential that, implementation of genomic selection and other improved practices (nutrition, healthcare, etc.) can lead to rapid improvement in traits of economic importance in African livestock populations. The African livestock populations in the context of this review are limited to cattle, goat, pig, poultry, and sheep, which are mainly exploited for meat, milk, and eggs. This review examines the current state of livestock productivity in Africa, the main challenges faced by the sector, the role of various stakeholders and discusses in-depth strategies that can enable the application of genomic technologies for rapid improvement of livestock traits of economic importance

Diversidad genética y estructura de población de cabras autóctonas nigerianas usando marcadores microsatélites DNA

Twenty-nine microsatellite markers were used to evaluate genetic diversity and rela-tionships among three Nigerian goat breeds and to compare with one South African and one European goat breeds as outgroups. A total of 244 goats from the Sahel (47), Maradi (47), and West African Dwarf (67) breeds; and as outgroup: Kalahari (47) and Saanen (36) breeds were included. DNA was extracted from blood preserved on FTA Classic cards according to manufacturer’s protocol. The microsatellite regions were amplified using thermal cycler. Mean number of allele (MNA), expected and observed Heterozygousities (He and Ho, respectively), Hardy-Weinberg Equilibrium (HWE) and genetic distances between populations were calculated. A dendogram was constructed to reveal evolutionary trend in the studied breeds. A genetic structure of the populations was performed using STRUCTURE. Genetic diversity was high with MNA per locus ranging from 6.69 to 8.79 for Kalahari and West African Dwarf, respectively. Ho values ranged from 59 % for West African Dwarf to 64.9 % for Saanen. The highest He estimates were observed in the West African Dwarf (70 %). The lowest He (66.5 %) was observed in Saanen population. The Mean Fis values for the studied populations ranged from 0.055 to 0.148 for Kalahari and West Africa Dwarf, respectively. Genetic distances between populations revealed the least genetic relationship between Saanen and Maradi (0.386) and highest between Maradi and Sahel (0.025). The HWE test revealed eighteen, seventeen, thirteen, twenty-three, and twenty-one loci were in HWE (p>0.05) in Maradi, West African Dwarf, Sahel, Saanen, and Kalahari, respectively. A gra-phic representation of the STRUCTURE analysis revealed that Nigerian goats descended from a common ancestor different from South African and European breeds used as outgroups

Prevalence of Coat Colour Phenotypes in West African Dwarf Sheep Reared by Small Holder Farmers in South Western Nigeria

The West African Dwarf (WAD) sheep reared extensively by small holder farmers in South Western Nigeria has not been selected based on preference for coat colour, which varies considerably but without adequate information on the current distribution. The prevalence of different coat colour phenotypes was therefore investigated based on a total randomly sampled size of 9, 195 sheep (5,978 females and 3,217 males) from February to October, 2011. A total of 17 different colour patterns including 3 solid colours (white, black and brown) were identified in the breed. Phenotypes mainly influenced by phaeomelanin pigment, considered to be governed by a dominant allele (Awt) include: predominantly white with black marking, solid white, white and black in approximately equal proportions, spotted white, white and brown in approximately equal proportions, buckskin, tan, badgerface and grey. The remaining phenotypes (black with white marking, brown, black, spotted black, spotted brown, black and brown, brown with white marking and Swiss marking) reflected the presence of eumelanin pigment governed by Aa recessive allele. Based on the two pigment types, 71.58% and 28.42% of sheep had coat colour predominated by phaeomelanin and eumelanin pigments, respectively. Result of chi square (X2) analysis showed that the difference between observed and expected frequencies was significant (P=.05) implying that there was a deviation from the expected 3:1 Mendelian ratio. Conscious selection could be embarked upon to investigate and conserve phenotypes that are more genetically superior in terms of productivity and adaptation