African Goat Breeds Research Articles

Effect of lactic acid bacteria administered as feed supplement on the weight gain and ruminal pH in two South African goat breeds

Antibiotics as growth promoters are banned in most European countries, because of antibiotic resistance and residues in animal products, and the release of recalcitrant antibiotics into the environment. Probiotics are the preferred alternative, because of no harmful attributes when compared to antibiotics, and the additional advantage of the ability to stabilise the microbial communities in the gut. We investigated the effects of LAB on the growth performance of South African goats. Randomly selected 17 Specked and 18 Boer goats were divided into five treatment groups according to sex and breed and were placed in an experimental trial for 30 days. Ruminal fluid was collected before and after the trial to monitor the changes in the pH. Data collected were analysed using a one-way analysis of variance (ANOVA) (SAS, version 9.4). Results revealed that LAB supplementation had no effect on feed intake in all experimental groups. However, the average weight gain was higher in the LAB groups when compared to other groups. Sex and breed had effects on final body weight; that is male (18.4 kg) goats are heavier than females (15.3 kg) averagely, irrespective of the breed, and the Boer goats are heavier than Specked irrespective of gender. The pH decreased averagely from 7.01 to 6.33 across all treatments, confirming the modulatory effect of the administered lactic acid bacteria. The findings in this study suggested that LAB as probiotics may induce beneficial effects in goats by enhancing weight gain, dropping the gut pH, thus maintaining an equilibrium of ruminal microbiota.

Timing and Extent of Inbreeding in African Goats.

Genetic characterization of African goats is one of the current priorities in the improvement of goats in the continent. This study contributes to the characterization effort by determining the levels and number of generations to common ancestors (“age”) associated with inbreeding in African goat breeds and identifies regions that contain copy number variation mistyped as being homozygous. Illumina 50k single nucleotide polymorphism genotype data for 608 goats from 31 breeds were used to compute the level and age of inbreeding at both local (marker) and global levels (FG) using a model-based approach based on a hidden Markov model. Runs of homozygosity (ROH) segments detected using the Viterbi algorithm led to ROH-based inbreeding coefficients for all ROH (FROH) and for ROH longer than 2 Mb (FROH > 2Mb). Some of the genomic regions identified as having ROH are likely to be hemizygous regions (copy number deletions) mistyped as homozygous regions. Although the proportion of these miscalled ROH is small and does not substantially affect estimates of levels of inbreeding for individual animals, the inbreeding metrics were adjusted by removing these regions from the ROH. All the inbreeding metrics varied widely across breeds, with overall means of 0.0408, 0.0370, and 0.0691 and medians of 0.0125, 0.0098, and 0.0366 for FROH, FROH > 2Mb, and FG, respectively. Several breeds (including Menabe and Sofia from Madagascar) had high proportions of recent inbreeding, while Small East African, Ethiopian, and most of the West African breeds (including West African Dwarf) had more ancient inbreeding.

Meat quality characteristics of two South African goat breeds after applying electrical stimulation or delayed chilling of carcasses

Two post slaughter procedures namely, electrical stimulation (220V for 30s, then chilling at 4°C) and delayed chilling without electrical stimulation (10–15°C for 6h, 4°C until 24h) were tested on carcasses of Boer and South African indigenous goats (n=10 goats per breed). The aim of the study was to assess the ideal slaughter conditions for optimum goat meat quality. Temperature and pH profiles, instrumental colour measurements (CIE L*, a*, b*, Chroma and hue angle), surface myoglobin pigments (deoxymyoglobin, oxymyoglobin and metmyoglobin), water holding capacity (WHC), thawing losses, cooking losses, sarcomere lengths and Warner Bratzler shear force (WBSF) values were evaluated on M. longissimus dorsi (LD) and semimembranosus (SM) samples. Both electrical stimulation and delayed chilling treatments resulted in sarcomeres longer than 1.9μm, therefore there were no cold shortening effects. The SM samples of electrical stimulation treatment had lower (P<0.01) WBSF values than corresponding samples of delayed chilling treatment. The LD samples of delayed chilling treatment recorded higher instrumental colour values than corresponding samples of electrical stimulation treatment. Electrical stimulation led to an increase (P<0.05) in cooking losses, but had no effect (P>0.05) on WHC, or thawing losses of LD samples. Breed had no effect (P>0.05) on meat quality characteristics. This study confirms that electrical stimulation has a higher potential than delayed chilling of carcasses in improving goat meat tenderness. Delayed chilling could be more beneficial in improving goat meat colour.

Population genomic structure and linkage disequilibrium analysis of South African goat breeds using genome-wide SNP data.

The sustainability of goat farming in marginal areas of southern Africa depends on local breeds that are adapted to specific agro-ecological conditions. Unimproved non-descript goats are the main genetic resources used for the development of commercial meat-type breeds of South Africa. Little is known about genetic diversity and the genetics of adaptation of these indigenous goat populations. This study investigated the genetic diversity, population structure and breed relations, linkage disequilibrium, effective population size and persistence of gametic phase in goat populations of South Africa. Three locally developed meat-type breeds of the Boer (n=33), Savanna (n=31), Kalahari Red (n=40), a feral breed of Tankwa (n=25) and unimproved non-descript village ecotypes (n=110) from four goat-producing provinces of the Eastern Cape, KwaZulu-Natal, Limpopo and North West were assessed using the Illumina Goat 50K SNP Bead Chip assay. The proportion of SNPs with minor allele frequencies >0.05 ranged from 84.22% in the Tankwa to 97.58% in the Xhosa ecotype, with a mean of 0.32±0.13 across populations. Principal components analysis, admixture and pairwise FST identified Tankwa as a genetically distinct population and supported clustering of the populations according to their historical origins. Genome-wide FST identified 101 markers potentially under positive selection in the Tankwa. Average linkage disequilibrium was highest in the Tankwa (r(2) =0.25±0.26) and lowest in the village ecotypes (r(2) range=0.09±0.12 to 0.11±0.14). We observed an effective population size of <150 for all populations 13 generations ago. The estimated correlations for all breed pairs were lower than 0.80 at marker distances >100kb with the exception of those in Savanna and Tswana populations. This study highlights the high level of genetic diversity in South African indigenous goats as well as the utility of the genome-wide SNP marker panels in genetic studies of these populations.

Targeted high-throughput growth hormone 1 gene sequencing reveals high within-breed genetic diversity in South African goats.

This study assessed the genetic diversity in the growth hormone 1 gene (GH1) within and between South African goat breeds. Polymerase chain reaction-targeted gene amplification together with Illumina MiSeq next-generation sequencing (NGS) was used to generate the full length (2.54kb) of the growth hormone 1 gene and screen for SNPs in the South African Boer (SAB) (n=17), Tankwa (n=15) and South African village (n=35) goat populations. A range of 27-58 SNPs per population were observed. Mutations resulting in amino acid changes were observed at exons 2 and 5. Higher within-breed diversity of 97.37% was observed within the population category consisting of SA village ecotypes and the Tankwa goats. Highest pairwise FST values ranging from 0.148 to 0.356 were observed between the SAB and both the South African village and Tankwa feral goat populations. Phylogenetic analysis indicated nine genetic clusters, which reflected close relationships between the South African populations and the other international breeds with the exception of the Italian Sarda breeds. Results imply greater potential for within-population selection programs, particularly with SA village goats.

Genetic diversity and differentiation in nine West African local goat breeds assessed via microsatellite polymorphism

This study was carried out to study the genetic relationship among nine (9) West African goat breeds out of which 6 (Guinea dwarf, Kirdi, Ghana dwarf, Mossi, Togo dwarf, Senegal dwarf) were of the trypanotolerant type and 3 (Mali Sahel, Mauritania Sahel, Chad Sahel) were of the trypanosusceptible type. One hundred ninety nine (199) animals were genotyped using 10 microsatellites. The microsatellites loci analysed were highly polymorphic with a mean number of alleles of 11.7 ± 3.7 ranging from 6 to 20. Observed heterozygosities ranged from 0.603 ± 0.164 (Togo dwarf) to 0.726 ± 0.166 (Chad Sahel). It was lower than expected heterozygosity in most of the breeds indicating a deviation from Hardy Weinberg equilibrium. The Fst measure of genetic distance between pairs of populations showed the highest distance (0.098) between Kirdi and Guinea dwarf which presented an isolated position from the other breeds and the lowest distance (0.025) between Togo dwarf and Mossi. Our study showed that the genetic relationships among the concerned breeds correspond to their geographical distribution. In addition, Guinea dwarf is strongly separated from the other breeds.

Serum progesterone as an indicator of cyclic activity in post-partum goat does

The aim of this trial was to assess post-partum ovarian activity of the does of two South African goat breeds from their serum progesterone concentrations. Between seven and 100 days post-partum, does from the Boer goat breed and an indigenous rural goat type were allocated to two nutritional treatments within breed. One group per breed received a concentrated diet in an intensive feeding programme. The other group per breed was subjected to a low level of nutrition through the grazing of the natural pasture in an extensive (veld) grazing system. Blood samples were collected weekly from five does per breed per treatment. Serum progesterone concentrations were determined using a Gamma Coat TM [128] progesterone radioimmunoassay kit (Sorin Diagnostics, France). Large variations in serum progesterone concentrations were recorded within and between breeds and nutritional regimens. Irrespective of breed, in the extensive groups subjected to the low level of nutrition, mean peak serum progesterone concentrations never exceeded 0.2 ng/mL. This suggests that throughout the experimental period, ovarian activity remained low in the extensive groups. It was concluded that nutritional regimen plays a significant role in ensuring high ovarian activities. Furthermore, the higher mean serum progesterone levels in the Boer goat indicate an earlier and higher oestrous activity, compared to the indigenous does.

Diversity and Genetic Relationships among Seven West African Goat Breeds

This study was carried out to determine the genetic relationships among seven west African goat breeds: Casamance Goat (Kolda, Senegal), Labe Goat (Fouta Djallon, Guinea), three Sahel Goat (Djoloff, Senegal; Maradi, Niger; Gorgol, Mauritania) red Sokoto Goat (Maradi, Niger) and Guera goat (Atar, Mauritania).The polymorphism of six microsatellites and the α s1 -casein locus was analysed. The six microsatellite loci were polymorphic with a mean number of alleles ranging from 2.71 to 4.0. At the α s1 -casein locus, A and B were the most frequent alleles, which are known to be associated with a high level of protein synthesis. A neighbour-joining tree and a Principal Component Analysis were performed and the reliability of both methods was tested. Our study shows that the genetic relationships among the breeds analysed correspond to their geographical distribution and in addition, that the Labe Goat is strongly separated from the other breeds. Among the seven markers used, four have an effect on the distribution of breeds while three seem to be non-informative.

Genetic Characterization of Indigenous Goats of Sub-saharan Africa Using Microsatellite DNA Markers

Genetic diversity of sub-Saharan African goats was assessed using 19 microsatellite markers. Breeds were sampled from eastern Africa (Maasai, Kigezi, Mubende, North West Highland, Arsi-Bale), southern Africa (Ndebele, Pafuri) and West Africa (West African Dwarf, Maure, Djallonke). European breeds (Grisons Striped, Toggenburg), Asian breeds (Mongolian Cashmere, Bandipur) and a Middle East breed (Arab) were also included. The mean number of alleles per locus and average gene diversity ranged from 5.26′0.464 (Djallonke) to 7.05′0.516 (Mubende) and from 0.542′0.036 (Pafuri) to 0.672′0.031 (Ndebele), respectively. The between breeds variation evaluated using G S T and 0 were found to account for 14.6% (0) and 15.7% (G S T ) of the total genetic variation. The D A measure of genetic distance between pairs of breeds indicated that the largest genetic distance was between Pafuri and Djallonke while the lowest genetic distance was between Arsi-Bale and North West Highland. A neighbour-joining tree of breed relationships revealed that the breeds were grouped according to their geographic origins. Principal component analysis supported the grouping of the breeds according to their geographic origins. It was concluded that the relationships of sub-Saharan African goat breeds were according to their geographical locations implying that the goats of eastern Africa, West Africa and southern Africa are genetically distinct. Within each sub-region, goat populations could be differentiated according to morphological characteristics.