Nigerian Sheep Research Articles

Foramen Magnum and Dental Osteometry of Balami, Uda, and Yankasa Breeds of Sheep

The increasing demand for animal protein, particularly meat, requires a thoughtful approach to selecting the type of meat-producing animal to achieve maximum yields. This is crucial to maintain food security. This study aimed to evaluate and compare some skull osteometries. A total of 60 each of Balami, Uda, and Yankasa sheep (30 adult males and 30 adult females) were used in this study. The skulls were macerated using a hot water technique. Then 7 parameters were measured using a digital Vernier caliper. The obtained data were analyzed using ANOVA (p < 0.05). The result of this study was that the mean foramen magnum height (FMH) was highest, medium, and lowest in the Balami (2.1 ± 0.1 cm), Uda (1.9 ± 0.1 cm), and Yankasa (1.8 ± 0.0 cm) breeds, respectively, and vice versa in the foramen magnum index (FMI). The foramen magnum width (FMW) was similar in Balami and Uda but higher than in Yankasa (1.8 ± 0.1 cm). The FMH, FMW, and FMI were similar within sexes of the same breeds in Balami, Uda, and Yankasa. The mean dental length (DL), oral palatal length (OPL), and length of the upper molar row (LUM) were highest and lowest in Balami and Yankasa, respectively, while the mean length of the upper premolar row (LUP) was highest and lowest in Balami and Uda, respectively. The (DL), (OPL), (LUM), and (LUP) were higher in males than females in Balami and vice versa in Uda and Yankasa. In conclusion, craniometric values, including foramen magnum and dental osteometry, of indigenous Nigerian sheep breeds were used to compare them to other breeds and among themselves. It could also guide oral surgery and assist in identifying sheep breeds through comparative study.

Polymorphism of prion protein gene (PRNP) in Nigerian sheep

ABSTRACT Polymorphism of the prion protein gene (PRNP) gene determines an animal’s susceptibility to scrapie. Three polymorphisms at codons 136, 154, and 171 have been linked to classical scrapie susceptibility, although many variants of PRNP have been reported. However, no study has investigated scrapie susceptibility in Nigerian sheep from the drier agro-climate zones. In this study, we aimed to identify PRNP polymorphism in nucleotide sequences of 126 Nigerian sheep by comparing them with public available studies on scrapie-affected sheep. Further, we deployed Polyphen-2, PROVEAN, and AMYCO analyses to determine the structure changes produced by the non-synonymous SNPs. Nineteen (19) SNPs were found in Nigerian sheep with 14 being non-synonymous. Interestingly, one novel SNP (T718C) was identified. There was a significant difference (P < 0.05) in the allele frequencies of PRNP codon 154 between sheep in Italy and Nigeria. Based on the prediction by Polyphen-2, R154H was probably damaging while H171Q was benign. Contrarily, all SNPs were neutral via PROVEAN analysis while two haplotypes (HYKK and HDKK) had similar amyloid propensity of PRNP with resistance haplotype in Nigerian sheep. Our study provides valuable information that could be possibly adopted in programs targeted at breeding for scrapie resistance in sheep from tropical regions.

Genetic diversity of Nigerian Indigenous Sheep breeds at the β-Lactoglobulin gene locus

The study assessed genetic diversity of four Nigerian sheep populations namely; Balami, Yankasa, Ouda and West African Dwarf (WAD) making use of blood sample. Extracted DNAs were used to study polymorphism at the β-lactoglobulin gene locus using RLFP-PCR process. Results revealed the percentage polymorphic locus was 100% while Shannon’s information index, observed homozygosity, expected heterozygosity, unbiased expected heterozygosity and fixation index were 0.656, 0.516, 0.464, 0.477 and -0.075, respectively. The gene flow (Nm) for all the population was estimated to be 7.65. The pairwise Fst was low and within the range of 0.0004(between Balami and WAD) to 0.0520 (between Balami and Yankasa). Variation within and between the populations of sheep shows that a large proportion of the observed variance (98% at p &lt; 0.01) occurred within the breeds while only 2 % of the variance (p &lt; 0.01) was contributed due to differences among the breeds. The nearest genetic distance was between the Balami and WAD (0.001) and between Ouda and the WAD (0.001). Phylogenetic analysis revealed three clusters. The present study showed that effort should be made to prevent the wearing away of the genetic make-up of the sheep populations considering the negative fixation index.

Genetic polymorphism of myostatin (MSTN) in Nigerian sheep breeds

Myostatin (MSTN) also known as growth differentiation factor 8 (GDF-8) has been implicated to play an important role in growth regulation, and it is a candidate gene in marker assisted selection (MAS). This study was carried out to identify the polymorphism of MSTN gene as a genetic marker for growth traits in Nigerian indigenous sheep. Genomic DNA (gDNA) was extracted from blood samples of Balami, Yankasa, Uda and West African Dwarf (WAD) breeds of sheep. Parts of 5’UTR, intron and exon1 (614bp) was amplified using a primer sequence designed by FastPCR-primer software. The amplicons were digested with restriction enzyme HaeIII and the fragments produced were stained with luminescent dye and run on gel electrophoresis. The genetic structure of the sampled population was investigated after analysis with POPGENE32 software. The HaeIII digested results showed that Myostatin has three polymorphs (AA, AB and BB), controlled by two alleles (A and B), with B having a higher allelic frequency (82.84%) and BB genotype has the highest frequency of 73%. The sampled population showed a deviation from Hardy-Weinberg equilibrium (p&lt;0.05) while the F-statistics results of the Nigerian breeds of sheep showed the breeds are genetically identical (33.40%) within them. The genetic distance matrix established that Uda and Yankasa show the greatest distant (3.00%) while Uda and WAD are almost identical (99.85%). The four breeds of sheep studied showed polymorphism for Myostatin gene in the intron 1 and exon 1. Myostatin, therefore, could be considered a candidate gene for MAS

EFFECT OF FIBRE PRE-TREATMENT AND PROCESSING ON THE WATER ABSORPTION AND MOISTURE PROPERTIES OF THE NIGERIAN SHEEP FIBRES

The effect of fibre pre-treatment and processing on the water absorption and moisture properties of the Nigerian sheep fibres has been studied. The sheared fibres were pretreated by soaking, washing, rinsing and drying in order to remove the unwanted impurities and inherent constituents present in the fibres. They were further processed by separating and carding to evaluate the changes that occur in their rate of water absorption at each stage. It can be observed that the fibres at the pre-treated stage absorbs more water and has higher moisture content because of the increased pore size due to its overlapping scales which reduces when separated and carded. Therefore, this research shows that the water absorption and moisture retention ability of the sheep fibres can be affected by different stages of pre-treatment, separation and carding.

Effect of maternal haemoglobin variants and lamb genotype on pre-weaning growth rate of sheep of Northern Nigerian and their crosses

&#x0D; &#x0D; &#x0D; &#x0D; Pre-weaning growth trait of sheep of Northern Nigerian (Balami, Uda and Yankasa) subjected to diallel crossing were estimated using 127 lambs. The study was conducted at National Animal Production Research Institute (NAPRI), Zaria, Nigeria. Blood (5ml) samples were collected from ewes and rams that produce the lambs to evaluate the effect of parental haemoglobin (Hb) variant on the pre-weaning growth rate of lambs. Weight and average daily gain (ADG) of lambs were obtained at 2 weeks interval to 12th week. The data obtained were subjected to analysis of variance using General Linear Model Procedure of SAS. Pair-wise difference was used to separate the mean. Frequency of ewes’ Hb genotype in relation to lambs was sorted and tested with Chi Square Procedure of SAS. The result showed that HbAB was the predominant (P&lt;0.01) variant in the studied population, observed in 60% of the ewes and 100% of the sires. Allele A had the highest frequency (62%) in the dam population. The genotypic distribution of Hb variants in the population significantly deviated from Hardy Weinberg equilibrium (χ2 = 50.8, P&lt;0.01). HbAB and HbBB dams gave birth to lambs that were heavier (P&lt;0.01) than lambs from HbAA from birth to 12 weeks of age. Crossbred lambs from Balami rams and Uda ewes (BL x UD) recorded the highest weight (4.47±0.20 kg) at birth while the least weight (1.73±0.20 kg) at birth was obtained from crossbred lambs given birth to by Yankasa rams and Balami ewes (YK X BL). Pure Balami lambs (BL X BL) was outstandingly superior (P&lt;0.05) to lambs from other genotypes starting from the second week of age up to weaning (12th week). BL X BL also recorded the highest (238.09±12.42 g) average daily gain from birth to 2 weeks of age (ADG2). The ADG decreased linearly as the lambs advanced in age from birth to weaning. Balami sheep are capable of expressing their genetic potentials (better growth than others) in the Northern Guinea Savannah zone of Nigeria. Genetic improvement of growth traits of Nigerian sheep using indigenous stock should focus on the exploitation of genetic potentials in terms of faster growth rate of Balami sheep.&#x0D; &#x0D; &#x0D; &#x0D;

Genetic variability of Nigerian sheep breeds at the insulin-like growth factor-1 (IGF-1) gene locus

The genetic variability of some Nigerian breeds of sheep at the IGF 1 locus was investigate blood samples from 150 sheep (50 each of Yankasa, Balami and Uda sheep) were collected from the Maiduguri abbatoir and analysed at the Biotechnology centre of the University of Maiduguri. A relatively high level of genetic variability was detected in Nigerian sheep; the mean observed heterozygosity (Ho) and expected heterozygosity (He) values were 0.433 and 0.476, respectively. Comparison of expected heterozygosity of alleles between the populations showed that yankasa was the most heterozygous of the sheep populations though the unbiased expected heterozygosity (0.503) for the Yankasa was the same as that of the Balami. All populations were 100% polymorphic at the IGF 1 locus with fixation index ranging from -0.169 to 0.378 and a mean of 0.093, which suggests a general pattern of random mating. Similarly, low mean values for Fis (0.093), F (0.089), Fis (0.089), Fit (0.130) and Fst (0.045) supports the assertion that inbreeding was limited due to outcrossing with relatively high level of gene-flow (Nm = 5.292). The analysis of molecular variance (AMOVA) revealed that only 1% of the total variations observed in the sampled populations is accounted for by the population differences while individual differences accounted for 85%. The UPGMA phylogenetic tree revealed that the Uda and Yankasa populations are closer to each than each is to Balami. Thus, it can be concluded that sufficient genetic variation exist in the studied Nigerian sheep breeds and these populations are unlikely to decline due to inbreeding.&#x0D;

Effect of breed, chilling duration and processed product on the quality characteristics of mutton

An experiment was conducted to evaluate the effect of breed, chilling duration and processed product on the quality characteristics of mutton. A total of nine (9) mature rams of 12 months of age (25 Kg) managed on the same system were used. The animals were kept for 24 hours where only water was provided to clear the gut content before slaughter. The experiment was carried out in a factorial arrangement (3 x 3 x 3) of a completely randomized design consisting of three breeds of sheep (Balami, Uda and Yankasa), three chilling durations (0, 24 and 48 hours) and three processed products (Balangu, Tsire and Tukunya). The result revealed that there was no significant (P&gt;0.05) effect of breed on proximate composition of fresh mutton. There was significant (P&lt;0.05) effect of processed product on the proximate composition of mutton. Moisture content was higher in Balangu (54.93 %), followed by Tukunya (51.74 %) and lower in Tsire (41.00 %). Crude protein content was higher in Balangu (33.83 %), followed by Tukunya (29.63 %) which was at par wih Tsire (29.51 %). Ash content was higher in Tsire (6.61 %), followed by Balangu (5.71 %) and lower in Tukunya (3.69 %). Significant (P&lt;0.05) chilling duration effect was obtained for bacteria count which was higher at 0 hours (2.25 x 103 cfu/g) chilling, followed by 24 hours (1.86 x 103 cfu/g) chilling. The same trend was observed for coliform count in which higher value was obtained at 0 hours (4.49 x 102 cfu/g) chilling, followed by 24 hours (3.04 x 102 cfu/g) chilling and 48 hours (2.93 x 102 cfu/g) chilling. Sensory properties of mutton from different breed differed significantly (P&lt;0.05) among processed products. The overall accepatability indicates that Tsire (7.60) product was more acceptable, followed by Tukunya (7.20) product while Balangu (6.86) product was less acceptable. The microbial count obtained from the study was within the acceptable range (&lt; 3.5 log HACCP 2002). It can be concluded that processed meat products (Tsire, Balangu and Tukunya) obtained from different breeds of Nigerian sheep (Balami, Uda and Yankasa) were not homogenous in their proximate composition. It is therefore recommended that fresh mutton should be chilled for 24 to 48 hours with little or no bacteria while fresh meat from the three breed of sheep (Balami, Uda and Yankasa) can be chilled for 24 to 48 hours with little or no bacteria and can be processed into different products (Tsire, Balangu and Tukunya).

First molecular description, phylogeny and genetic variation of Taenia hydatigena from Nigerian sheep and goats based on three mitochondrial genes

BackgroundCysticercosis caused by the metacestode larval stage of Taenia hydatigena is a disease of veterinary and economic importance. A considerable level of genetic variation among isolates of different intermediate hosts and locations has been documented. Generally, data on the genetic population structure of T. hydatigena is scanty and lacking in Nigeria. Meanwhile, similar findings in other cestodes like Echinococcus spp. have been found to be of epidemiological importance. Our aim, therefore, was to characterize and compare the genetic diversity of T. hydatigena population in Nigeria based on three mitochondrial DNA markers as well as to assess the phylogenetic relationship with populations from other geographical regions.MethodsIn the present study, we described the genetic variation and diversity of T. hydatigena isolates from Nigerian sheep and goats using three full-length mitochondrial genes: the cytochrome c oxidase subunit 1 (cox1), NADH dehydrogenase subunit 1 (nad1), and NADH dehydrogenase subunit 5 (nad5).ResultsThe median-joining network of concatenated cox1-nad1-nad5 sequences indicated that T. hydatigena metacestodes of sheep origin were genetically distinct from those obtained in goats and this was supported by high FST values of nad1, cox1, and concatenated cox1-nad1-nad5 sequences. Genetic variation was also found to be higher in isolates from goats than from sheep.ConclusionsTo the best of our knowledge, the present study described the genetic variation of T. hydatigena population for the first time in Nigeria using full-length mitochondrial genes and suggests the existence of host-specific variants. The population indices of the different DNA markers suggest that analysis of long mitochondrial DNA fragments may provide more information on the molecular ecology of T. hydatigena. We recommend that future studies employ long mitochondrial DNA sequence in order to provide reliable data that would explain the extent of genetic variation in different hosts/locations and the biological and epidemiological significance.

Association of IGF 1 gene polymorphisms with some morphometric traits of Nigerian indigenous sheep breeds

The relationship between IGF 1 gene polymorphisms and some morphometric traits of the Balami, Uda and Yankasa sheep breeds of Nigeria was investigated. Blood samples and morphometric measurements were obtained from 150 sheep (50 for each of the three breeds) at the Maiduguri Livestock market and abattoir while DNA was extracted at the Biotechnology laboratory of the University of Maiduguri. Evaluation of results revealed 2 alleles (A and B) and 3 genotypes (AA, AB and BB) for all the breeds. The Uda and Yankasa breeds had higher frequency of allele B (0.64 and 0.56, respectively) while Balami had higher allele frequency for A (0.61). Balami and Yankasa had high heterozygosity for IGF-1 gene while Uda had high homozygosity for B. For Balami sheep, the genotype BB had higher (P < 0.05) body weight and heart girth (56 kg and 79 cm, respectively) than AB for body weight (45.80 kg) and BB for heart girth (69.67 cm). Conversely, genotype AA had higher body length (94.33 cm) than AB (73.80 cm). IGF 1 gene polymorphisms did not significantly (P < 0.05) affect most morphometric traits of the Yankasa and Uda sheep except height at withers where the genotype AB had higher (P < 0.05) height at withers (71.77 cm) than AA (53.50 cm) for Yankasa sheep. Thus, the three breeds were found to be 100% polymorphic at the regulatory region of IGF-1 locus and this gene may be used as a marker for some morphometric traits in Nigerian indigenous sheep. Keywords : body weight, heart girth, height at withers, breeds, sheep

Relationship between morphological traits, body indices and body condition score as welfare indicators of Nigerian sheep

The relationship between morphological traits and body condition score (BCS) of indigenous sheep breeds was assessed. A total number of 400 indigenous sheep were sampled. Twelve body measurements were taken from these sheep; these measurements were then used to estimate body indices of these animals. Data were subjected to General Linear Model and correlation using SAS. Results revealed that there were significant effects (p&gt;0.05) of sex on some morphological traits and body indices of the sheep. There were negative and significant (p&lt;0.01) correlation between body condition score and height index, over increased index, index of chest compression, cephalic index and dactyl thorax index. There were positive and significant (p&lt;0.01) correlation between body condition score and length index, weight, thoracic development and conformation index. It was concluded that there was low correlation between BCS, morphological traits and body indices of sheep except in conformation index. This implies that increase in conformation index will result in increase in BCS and vice-versa.

Genetic diversity at four Nigerian sheep breeds assessed by variation of albumin and carbonic anhydrase in cellulose acetate electrophoretic systems

Abstract. The aim of the study was to evaluate the occurrence and distribution of variations in blood protein markers in sheep breeds in Nigeria and to evaluate the relationships that exist among them. A total of 100 sheep comprising of twenty-five each of Balami, Uda, Yankassa and West African Dwarf (WAD) breeds were sampled for biochemical studies. Blood was collected to determine variations at the Albumin and Carbonic Anhydrase structural protein loci using cellulose acetate electrophoresis. All tested loci were polymorphic yielding four allelic variants (CAF, CAS, AlbA, and AlbB) at the two protein loci. Genetic variability in the studied population was accessed using heterozygosity (observed – Ho and expected – He), effective number of alleles (Ne), fixation index (F) and gene flow (Nm). Genotypic frequencies ranged from 0.01 to 0.62 for Ca and 0.25 to 0.49 for Alb loci. Estimated heterozygosity values ranged from 0.32±0.28 at Balami sheep to 0.70±0.22 in WAD with a global average estimated at 0.43±0.09 for all the breeds studied. The gene flow values for each of the loci studied were 0.82 and 1.24 for Alb and Ca, respectively, with an average value of 1.03. The results showed that Yankassa and Balami sheep populations are more genetically (Nei's genetic identify value – 0.99) alike compared to Yankassa and WAD (0.73). Based on the values of heterozygosity (mean He =0.70 and Ho =0.45) assessed by variation of albumin and carbonic anhydrase the most genetic diverse is WAD sheep breed among the studied populations.

Interrelationship studies between heat stress traits, blood andserum biochemical indices of extensively managed Nigerian Sheep

The exposure of sheep to elevated ambient temperatures induces an increase in the dissipation of excess body heat, in order to overcome this excessive environmental heat load. Dissipation of excess body heat is emitted by evaporation of water from the respiratory tract and skin surface via panting and sweating.The following heat stress traits were measured; body temperature, rectal temperature, pulse rate and respiratory rate after the sunrise and before the sunset. While blood and serum biochemical indices measured were blood glucose, total serum protein, globulin, cholesterol and triglycerides. No significant relationship(P>0.05) was recorded between heat stress traits and blood biochemical indices studied. However, we observed a positively significant (P<0.01) relationship betweenblood and serum biochemical indices studied. Similarly, a positively significant (P<0.01) relationship was observed between heat stress traits examined.

Morphometric characterization of Nigerian indigenous sheep using multifactorial discriminant analysis

Adequate knowledge of diversities within and between animal populations will not only help in reducing misidentification in animal husbandry but also aid conservation of many important endangered alleles. A total number of 1195 animals comprising 380 Yankasa sheep, 414 Uda sheep, 224 Balami sheep and 177 West African Dwarf (WAD) sheep were sampled from Osun and Oyo states, South Western Nigeria. Yankasa and WAD were sampled from traditionally managed flock while Balami and Uda sheep were obtained from markets in these states. Seventeen (17) morphometric characters were measured to study their phenotypic variations. The characters measured include rump width (RW), rump length (RL), tail length (TL), wither height (WH), heart girth (HG), paunch girth (PG), rump height (RH), ear length (EL), foreleg length (FLL), rear-leg length (RLL), body length (BL), shoulder width (SW), neck circumference (NC), head length (HeL), head width (HW), horn length (HL) and hock length (HoL). Stepwise multifactorial discriminant analysis was explored to check traits that best differentiate the Nigerian sheep. Length of tail was the most discriminating character among the eight distinguishing traits found. Longest genetic distance was found between WAD and Uda sheep while the closest breeds were Balami and Uda, as indicated by the Euclidian distance. The large Euclidian distance obtained for genetic gap between Uda and WAD sheep gives prospect for improvement if they are crossbred. Since Uda and WAD have been reared successfully in the arid Northern region and trypano-endemic region of Southern humid Nigeria, respectively, crossing WAD with Uda will produce a relatively large, heat tolerant and trypanotolerant hybrid. Key word: Phenotypic variation, Nigerian sheep, discriminant analysis.

A Novel TaqI Polymorphism in the Coding Region of the Ovine TNXB Gene in the MHC Class III Region: Morphostructural and Physiological Influences

The tenascin-XB (TNXB) gene has antiadhesive effects, functions in matrix maturation in connective tissues, and localizes to the major histocompatibility complex class III region. We hypothesized that it may influence adaptive physiological response through an effect on blood vessel function. We identified a novel g.1324 A→G polymorphism at a TaqI recognition site in a 454bp fragment of ovine TNXB and genotyped it in 150 Nigerian sheep using PCR-RFLP. The missense mutation changes glutamic acid (GAA) to glycine (GGA). Among SNP genotypes, significant differences (P<0.05) were observed in body weight and fore cannon bone length. Interaction effects of breed, SNP genotype, and geographic location had a significant effect (P<0.05) on chest girth. The SNP genotype was significantly (P<0.05) associated with physiological traits of pulse rate and skin temperature. The observed effect of this novel polymorphism may be mediated through its role in connective tissue biology, requiring further association and functional studies.

Gene Flow between Nigerian Sheep Breeds as Revealed by Microsatellite DNA Markers

The presence and level of gene flow between the four major Nigerian sheep breeds (West African Dwarf (WAD), Yankasa, Balami and Uda) was assessed using microsatellite DNA markers. DNA was extracted from 50μl of whole blood using the ZymoBeadTM Genomic DNA Kit The DNA was amplified by PCR in a MyCyclerTM Thermal Cycler (Biorad, Hercules, CA) using 15 microsatellite markers selected. DNA fragment analysis of microsatellite markers was carried out using the Applied BioSystems 3730xl DNA Analyzer (Applied Biosystems, Carlsbad, CA, USA). The level of gene flow or population structure was assessed by STRUCTURE software and barplots generated by DISTRUCT. At K=2, two clusters was constituted from breeds descending from Balami and Yankasa, both of which are from Northern region in Nigeria. At K=3 and K=4, one more cluster emerged and further analyses did not reveal any additional strong high level substructure, so separating the entire the entire datasets into 3 major clusters was chosen as the final configuration. There are however, several cases of admixtures in the genome of some of the individuals that constitute the cluster. Yankasa and Balami breed had more cases of admixtures followed by Uda while the WAD was the least breed with cases of admixtures. The values of genetic differentiation ranged between 0.11 and 0.19 with the highest mean value of 0.14. These results reveal the presence of gene flow among the Nigerian sheep breeds.

Morphological and microsatellite DNA diversity of Nigerian indigenous sheep

BackgroundSheep is important in the socio-economic lives of people around the world. It is estimated that more than half of our once common livestock breeds are now endangered. Since genetic characterization of Nigerian sheep is still lacking, we analyzed ten morphological traits on 402 animals and 15 microsatellite DNA markers in 384 animals of the 4 Nigerian sheep breeds to better understand genetic diversity for breeding management and germplasm conservation.ResultsMorphological traits of Uda and Balami were significantly (P < 0.05) higher than Yankasa, which were both higher than West African Dwarf (WAD) sheep. Stepwise discriminant analysis showed tail length, rump height, chest girth, ear length and chest depth as the most discriminating variables for classification. Mahalanobis distances show the least differentiation between Uda and Balami and the largest between WAD and Balami sheep. While 93.3% of WAD sheep were correctly assigned to their source genetic group, 63.9% of Yankasa, 61.2% of Balami and 45.2% of Uda were classified correctly by nearest neighbour discriminant analysis. The overall high Polymorphism Information Content (PIC) of all microsatellite markers ranged from 0.751 to 0.927 supporting their use in genetic characterization. Expected heterozygosity was high for all loci (0.783 to 0.93). Mean heterozygote deficiency across all populations (0.171 to 0.534) possibly indicate significant inbreeding (P < 0.05). Mean values for FST, FIT and FIS statistics across all loci were 0.088, 0.394 and 0.336 respectively. Yankasa and Balami are the most closely related breeds (DA = 0.184) while WAD and Balami are the farthest apart breeds (DA = 0.665), which is coincident with distance based on morphological analysis and population structure assessed by STRUCTURE.ConclusionsThese results suggest that within-breed genetic variation in Nigerian sheep is higher than between-breeds and may be a valuable tool for genetic improvement and conservation. The higher genetic variability in Yankasa suggests the presence of unique ancestral alleles reflecting the presence of certain functional genes which may result in better adaptability in more agro-ecological zones of Nigeria. These genetic characteristics are potentially useful in planning improvement and conservation strategies in Nigerian indigenous sheep.

Genetic diversity analysis of the mitochondrial D-loop of Nigerian indigenous sheep

Indigenous livestock resources are strategic in the socio-economics of rural agricultural systems to ensure food security in resource-poor countries. Therefore, better understanding of genetic variation holds the key to future utilization through conservation. We report the first analysis of genetic diversity of Nigerian sheep based on the D-loop region of the Ovis aries mitochondrial genome using 1 179 bases between sites 15 437 and 16 616 base pairs. A sample of 290 animals made up of Balami, West African Dwarf (WAD), Uda and Yankasa breeds were randomly collected from across Nigeria. Ninety-six haplotypes were observed with a high mean haplotype diversity of 0.899 ± 0.148. Gene diversity was highest in Uda (0.921 ± 0.021) and lowest in WAD (0.852 ± 0.061). Population specific FST indices varied from 0.00133 in Uda to 0.00335 in WAD. Yankasa had the highest number of polymorphic sites (201), while the least was in Uda (96). Analysis of molecular variance revealed that 0.23 percent of the variation is found among populations compared with 99.77 percent variation found within populations. The phylogenetic tree indicates that the mitochondrial lineages of these sheep breeds originated from a common source consistent with first divergence of Yankasa followed by WAD, while Balami and Uda remain more closely related. These results suggest that evolutionary divergence of Nigerian sheep breeds based on mitochondrial DNA D-loop sequence may be coincident with geographical distribution in Nigeria and suggest significant interbreeding. This could have implications for managing improvement and conservation strategies and long-term conservation of Nigerian indigenous sheep.

Multivariate analysis of morphostructural characteristics in Nigerian indigenous sheep

The population variability of three breeds of Nigerian sheep was investigated using multivariate discriminant analysis. The sampled populations comprised mature 331 Yankasa, 296 Uda and 166 Balami sheep kept by traditional farmers in northern Nigerian. A total of ten morphological traits (withers height, rump height, body length, face length, rump length, tail length, chest circumference, head width, shoulder width and rump width) were collected on each animal. The univariate analysis revealed that the body measures of Balami sheep were significantly larger (P<0.05) than others with the exception of tail length. Uda sheep also had higher mean values (P<0.05) than their Yankasa counterparts in all the morphological traits analysed. However, the stepwise discriminant analysis revealed that head width chronologically followed by tail length, chest circumference and body length were more discriminating in separating the three sheep populations. The Mahalanobis distance of the morphological traits between Yankasa and Balami sheep was longest (4.83) while the least differentiation was observed between Uda and Yankasa sheep (1.79). Nearest neighbour discriminant analysis showed that most Balami sheep (61.45%) were classified into their source genetic group. While 41.22% of Uda sheep were misclassified as Yankasa sheep, 35.35% of Yankasa were wrongly assigned as Uda sheep, showing the level of genetic exchange that has taken place between the two breeds overtime. The present phenotypic information could be complemented with genetic analyses; and serve as a basis for designing appropriate conservation, breeding and selection strategies for Nigerian sheep.

Effects of season and diurnal period on the body physiology of Nigerian sheep breeds

Effects of season and diurnal period on the body physiology of Nigerian sheep breeds