Blackhead Persian Research Articles

Comparison of Growth Performance, Carcass Yield and Meat Quality of Blackhead Persian with Red Masai Sheep under Feedlot in Tanzania

Comparison of Growth Performance, Carcass Yield and Meat Quality of Blackhead Persian with Red Masai Sheep under Feedlot in Tanzania

Sheep supplementation in the arid and semi-arid areas of northern Kenya

The objective of this study was to assess the effects of partial supplementation of 1.5 years old blackhead Persian sheep with hay, molasses and local salt (Chalbi salt). The nutritive values of hay, molasses and Chalbi salt were determined. The selected sheep were assigned to three treatments in a completely randomized design; 10 sheep were given to the farmer and were herded based on his management practice (denoted as treatment A), 10 were grazed for 5 h and later supplemented with 600 g of chopped hay mixed with molasses per sheep daily and Chalbi salt ad libitum (denoted as treatment B), 10 were introduced to a government research farm, Kenya Agricultural and Livestock Research Organization (KALRO-Marsabit) flock and managed on the free range with no supplementation except Chalbi salt. They were also grazed for 8 h daily (denoted as treatment C). Feed resources for partial supplementation were analysed for proximate analysis, Van soest, in-vitro dry matter digestibility and mineral profiles. Molasses was spread on hay to increase palatability and intake. Chalbi salt was provided ad libitum to the supplemented group. All 30 sheep were weighed weekly. The data on sheep weights were analyzed using Statistical Package for Social Sciences (SPSS). The mean sheep weight over the study period was higher among the supplemented group B (25.95 kg), followed by on-station research farm-managed group C (22.60 kg) and lastly farmer-managed group A (19.50 kg). Supplementation of sheep using local feed resources enhances weight gain and this is recommended, essentially in a weight-based marketing system. Keywords: Market, nutrients, sheep, supplement, weight.

Genetic Basis of Dorper Sheep (Ovis aries) Revealed by Long-Read De Novo Genome Assembly.

Dorper sheep (Ovis aries) (DPS), developed in the 1930s by crossing Dorset Horn and Blackhead Persian sheep in South Africa, is a world-famous composite breed for mutton production. The genetic basis underlying this breed is yet to be elucidated. Here, we report the sequencing and assembly of a highly contiguous Dorper sheep genome via integration of Oxford Nanopore Technology (ONT) sequencing and Hi-C (chromatin conformation capture) approaches. The assembled genome was around 2.64 Gb with a contig N50 of 73.33 Mb and 140 contigs in total. More than 99.5% of the assembled sequences could be anchored to 27 chromosomes and they were annotated with 20,450 protein-coding genes. Allele-specific expression (ASE) genes of Dorper sheep were revealed through ASE analysis and they were involved in the immune system, lipid metabolism, and environmental adaptation. A total of 5,701 and 456 allelic sites were observed in the SNP and indels loci identified from relevant whole-genome resequencing data. These allelic SNP and INDEL sites were annotated in 1,002 and 294 genes, respectively. Moreover, we calculated the number of variant sites and related genes derived from the maternal and paternal ancestors, revealing the genetic basis of outstanding phenotypic performance of Dorper sheep. In conclusion, this study reports the first reference genome of Dorper sheep and reveals its genetic basis through ASE. This study also provides a pipeline for mining genetic information of composite breeds, which has an implication for future hybrid-breeding practices.

Biocompatibility of an apical ring plug for left ventricular assist device explantation: Results of a feasibility pre-clinical study.

Patients receiving left ventricle assist devices (LVADs) as bridge to recovery remain a minority with 1%-5% of LVADs explanted after improvement of myocardial function. Nevertheless, considering the growing population of patients supported with LVADs, an increasing demand of new explantation strategies is expected in the near future. A novel plug for LVAD explantation has been developed and its biocompatibility profile needs to be proved. This study tested the biocompatibility of this novel plug in an in vivo ovine model. Six adult Blackhead Persian female sheep received plug implantation on the cardiac apex via minimally invasive approach and were clinically observed up to 90days. Echocardiography was performed to detect thrombus formation or further plug-related complications. After the observation period, euthanasia was performed and samples including the plug and the surrounding tissues were obtained to be analyzed with correlative light and electron microscopy. Organ necrosis, ischemia and peripheral embolism were investigated. Three animals survived surgery and completed the follow-up time without experiencing clinical complications. Echocardiographic controls excluded the presence of an intracavitary thrombus in the left ventricle (LV). Autopsy confirmed no signs of local infection, LV thrombus or peripheral embolism. Light and electron microscopy revealed an intact epithelium covering a layer of connective tissue on the plug surface facing the heart lumen. This novel apical plug for LVAD explantation allows for endothelial and connective tissue growth on its ventricular side within 90days from surgery. Further studies are required to fully demonstrate the biocompatibility of this apical plug and investigate the optimal anticoagulation regimen to be applied after implantation.

Whole-Genome SNP Characterisation Provides Insight for Sustainable Use of Local South African Livestock Populations.

Local cattle and sheep populations are important for animal production and food security in South Africa. These genetic resources are well adapted to the diverse climatic conditions and hold potential to be utilized in production systems subjected to climate change. The local beef breeds are well integrated into commercial livestock production systems with access to performance recording and genetic evaluations, while local sheep breeds are mainly utilised in smallholder and communal systems. The GeneSeek® Genomic Profiler™ Bovine 150 K SNP genotyping array was used to evaluate the diversity and inbreeding status of four indigenous (Boran, Drakensberger, Nguni, Tuli), two composite (Bonsmara and Beefmaster) and two exotic (SA Hereford and Charolais) beef breeds. The Illumina® Ovine 50 K SNP BeadChip was used to investigate five indigenous (Black Head Persian, Damara, Fat tail, Namaqua Afrikaner, Pedi) and three commercial (Dorper, Dohne Merino and SA Merino) populations. Although ascertainment bias was indicated by the low MAF (the autosome-wide proportion of SNPs with MAF< 0.05 ranged from 6.18 to 9.97% for cattle, and 7.59–13.81% for sheep), moderate genomic diversity was observed (mean Ho ranged from 0.296 to 0.403 for cattle, and 0.327 to 0.367 for sheep). Slightly higher levels of ROH-based inbreeding were calculated for cattle (FROH range: 0.018–0.104), than for sheep populations (FROH range: 0.002–0.031). The abundance of short ROH fragments (mean proportion of <4 Mb fragments: 0.405 for cattle, and 0.794 for sheep) indicated ancient inbreeding in both species. The eight cattle populations were categorized into indicine, taurine or Sanga subspecies based on principal component, model-based clustering and phylogenetic analyses, with high levels of admixture observed within the Drakensberger, Nguni and Tuli breeds. Within the sheep populations, a clear distinction could be seen between the dual-purpose breeds, the meat breed and the indigenous breeds. Despite directional selection practiced in the cattle breeds, genomic diversity was moderate with low inbreeding. The non-commercialized, indigenous sheep populations are more vulnerable with small effective populations. These results emphasise the value of genomic information for effective management to exploit the potential contribution of local genetic cattle and sheep resources in a changing environment.

Runs of homozygosity analysis of South African sheep breeds from various production systems investigated using OvineSNP50k data

BackgroundPopulation history, production system and within-breed selection pressure impacts the genome architecture resulting in reduced genetic diversity and increased frequency of runs of homozygosity islands. This study tested the hypothesis that production systems geared towards specific traits of importance or natural or artificial selection pressures influenced the occurrence and distribution of runs of homozygosity (ROH) in the South African sheep population. The Illumina OvineSNP50 BeadChip was used to genotype 400 sheep belonging to 13 breeds from South Africa representing mutton, pelt and mutton and wool dual-purpose breeds, including indigenous non-descript breeds that are reared by smallholder farmers. To get more insight into the autozygosity and distribution of ROH islands of South African breeds relative to global populations, 623 genotypes of sheep from worldwide populations were included in the analysis. Runs of homozygosity were computed at cut-offs of 1–6 Mb, 6–12 Mb, 12–24 Mb, 24–48 Mb and > 48 Mb, using the R package detectRUNS. The Golden Helix SVS program was used to investigate the ROH islands.ResultsA total of 121,399 ROH with mean number of ROH per animal per breed ranging from 800 (African White Dorper) to 15,097 (Australian Poll Dorset) were obtained. Analysis of the distribution of ROH according to their size showed that, for all breeds, the majority of the detected ROH were in the short (1–6 Mb) category (88.2%). Most animals had no ROH > 48 Mb. Of the South African breeds, the Nguni and the Blackhead Persian displayed high ROH based inbreeding (FROH) of 0.31 ± 0.05 and 0.31 ± 0.04, respectively. Highest incidence of common runs per SNP across breeds was observed on chromosome 10 with over 250 incidences of common ROHs. Mean proportion of SNPs per breed per ROH island ranged from 0.02 ± 0.15 (island ROH224 on chromosome 23) to 0.13 ± 0.29 (island ROH175 on chromosome 15). Seventeen (17) of the islands had SNPs observed in single populations (unique ROH islands). The MacArthur Merino (MCM) population had five unique ROH islands followed by Blackhead Persian and Nguni with three each whilst the South African Mutton Merino, SA Merino, White Vital Swakara, Karakul, Dorset Horn and Chinese Merino each had one unique ROH island. Genes within ROH islands were associated with predominantly metabolic and immune response traits and predomestic selection for traits such as presence or absence of horns.ConclusionsOverall, the frequency and patterns of distribution of ROH observed in this study corresponds to the breed history and implied selection pressures exposed to the sheep populations under study.

The genomic architecture of South African mutton, pelt, dual-purpose and nondescript sheep breeds relative to global sheep populations.

South Africa has a diverse array of phenotypically distinct and locally adapted sheep breeds that have been developed for different production systems ranging from mutton to wool and pelt, and some dual-purpose and nondescript breeds kept by smallholder farmers. This study investigated genetic diversity, population genetic structure and divergence between South African sheep breeds in order to gain an insight into breed history and genomic architecture aligned to breeding goals and production systems. The Illumina OvineSNP50 BeadChip was used to genotype 400 sheep belonging to 14 breeds representing mutton, pelt and mutton and wool dual-purpose breeds. Nguni sheep were included as a representative of indigenous nondescript breeds that are reared by smallholder farmers. Seeking a clearer understanding of the genetic diversity of South African breeds relative to global populations, 623 genotypes of sheep from worldwide populations were included in the analysis. These sheep breeds included six African, two Asian and eight European breeds. Across breeds, genetic diversity ranged from observed heterozygosity (H0 )=0.26±0.02 in Namaqua Afrikaner to H0 =0.38±0.01 in Dohne Merino. The overall mean H0 was 0.35±0.04. The African and Asian populations were the most inbred populations with FIS ranging from 0.17±0.05 in Grey Swakara and Ronderib Afrikaner sheep to 0.34±0.07 in the Namaqua Afrikaner. The South African Dohne Merino (FIS =0.03±0.01), SA Merino (FIS =0.05±0.04) and Afrino (FIS =0.09±0.02) and other global Merino-derived breeds were the least inbred. The first principal component explained 27.7% of the variation and separated the fat- and rump-tailed sheep (i.e. Swakara, Nguni, Blackhead Persian, Ethiopian Menzi, Meatmaster) from the Merino and Merino-derived breeds and the Dorset Horn. The second principal component separated the Merino and Merino-derived breeds from the English breed of Dorset Horn. Overall, South African indigenous breeds clustered together with indigenous breeds from other African and Asian countries. The optimal admixture cluster (K=20) revealed various sources of within- and amongst-breed genomic variation associated with production purpose, adaptation and history of the breeds. The Blackhead Persian, Nguni and Namaqua Afrikaner breeds differed significantly from other breeds, particularly with the South African Mutton Merino and Dorset Horn. Breed-differentiating SNPs were observed within genomic regions associated with growth, adaptation and reproduction. Genes such as RAB44, associated with growth and meat/carcass traits, differentiated the Blackhead Persian from the Dorset Horn and South African Mutton Merino. The MAP2 and HRAS genes, which are associated with immune traits involving Toll-like receptors and Chemokine signalling pathways, differentiated the Nguni from the Dorset Horn. The current results give insight into the current status of the sheep genetic resources of South Africa relative to the global sheep population, highlighting both genetic similarities as well as divergence associated with production systems, geographical distribution and local adaptation.

Examination of microsatellite markers of Dorper sheep breed

Number of not woolly and molty sheep exceeds 60 million throughout the world. Their numbers and their importance is growing, still they have appeared in the past two decades all over in North-America, Australia, New-Zealand and also in Europe. The South African Dorper has been a pioneer among them in Hungary. It was introduced in 2006 in the country. The Dorper sheep is the second largest breed in South Africa, which was developed from the crossing of Dorset Horn and the Blackhead Persian. The aim of the EU Member States in terms of this specific breed is increasing the small populations, improving the productive qualities, in addition to this avoiding inbreeding. However, finding appropriate breeding stock is difficult due to the small size of available populations and also to the suspected common of origin. With the help of various molecular genetic methods we could get a total view of the genetic background of these flocks. Nowadays the most commonly known and used genetic markers are microsatellites, because their applications give fast, accurate and easily reproducible results. There is no specific descriptive information on the genetic background of Dorper populations in the various EU countries , also regarding diversity between populations. Therefore in our work we want to optimize the conditions of applicability of 31 selected microsatellite reactions as a first step of mapping the entire genetic background of the different EU Dorper populations.

Effect of pre-slaughter conditions on physico-chemical characteristics of mutton from three sheep breeds slaughtered at a smallholder rural abattoir

The effects of pre-slaughter conditions and breed on physico-chemical characteristics of mutton were determined. The study was conducted at Adelaide Municipal abattoir in the Eastern Cape Province, South Africa. Records were taken from 84 sheep from the South African Mutton Merino, Blackhead Persian and Dorper breeds as identified on arrival at the abattoir. The South African Mutton Merino (SAMM) had the highest values for meat pH at 24 hours (pH24) (5.9 ± 0.64), lightness; L* (34.2 ± 0.97), yellowness; b* (12.2 ± 0.50) and Warner-Braztler shear force WBSF (26.8 ± 1.51). Linear relationships were also observed between pre-slaughter variables and physico-chemical characteristics of mutton. Principal Component Analysis (PCA) showed a large variation being contributed by meat pH24 and L*. It was therefore concluded that, transport time and lairage duration negatively affected the quality of mutton. Furthermore, breed affected the physico-chemical characteristics of meat.Keywords: Colour, meat pH24, Principal Component Analysis, transport time, Warner Braztler Shear Force

The Effects of Pre-slaughter Stress and Season on the Activity of Plasma Creatine Kinase and Mutton Quality from Different Sheep Breeds Slaughtered at a Smallholder Abattoir.

The objective of the current study was to determine the effect of pre-slaughter stress, season and breed on the activity of plasma creatine kinase (CK) and the quality of mutton. One hundred and seventy-three (173) castrated sheep from Dormer (DM), South African Mutton Merino (SAMM), Dorper (DP) and Blackhead Persian (BP) sheep breeds were used in the study. The animals were grouped according to age-groups as follows: Group 1 (6 to 8 months), Group 2 (9 to 12 months) and Group 3 (13 to 16 months). Blood samples were collected during exsanguinations using disposable vacutainer tubes for CK analysis. Representative samples of the Muscularis longissimuss thoracis et. lumborum (LTL) were collected from 84 castrated sheep, of different breeds (28 per breed) 24 h after slaughter. The following physico-chemical characteristics of mutton were determined; meat pH (pH24), color (L*, a* and b*), thawing and cooking losses and Warner Braztler Shear Force (WBSF). The activity of plasma CK was significantly higher (p<0.001) in summer (1,026.3±105.06) and lower in winter (723.3±77.75). There were higher values for L* (33.7±0.94), b* (11.5±0.48) and WBSF (29.5±1.46) in summer season than in winter season; L* (29.4±0.64), b* (10.2±0.33) and WBSF (21.2±0.99). The activity of plasma CK was influenced by the type of breed with Dormer having the highest (p>0.001) levels (1,358.6±191.08) of CK. South African Mutton Merino had higher values for pH24 (5.9±0.06), L* (34.2±0.97), b* (12.2±0.50) and WBSF (26.8±1.51) and Blackhead Persian had higher values (35.5±2.17) for cooking loss (CL%) than the other breeds. Computed Principal Component Analyses (PCA) on the activity of plasma CK and physico-chemical characteristics of mutton revealed no correlations between these variables. However, positive correlations were observed between pH24, L*, a*, b*, CL% and WBSF. Relationships between pre-slaughter stress, CK activity and physico-chemical characteristics of mutton were also observed. It was therefore concluded that although mutton quality and creatine kinase were not related, pre-slaughter stress, season and breed affected the activity of creatine kinase and mutton quality.

Prion protein (PrP) gene polymorphism in Red Maasai and Black Head Persian sheep breeds in Tanzania: Consistent profile regardless of locations

The status of scrapie in Africa is largely unknown. The susceptibility to scrapie and its pathology is determined by amino acid polymorphisms at positions 136 (A/V), 154 (R/H) and 171 (Q/R/H) of the ovine PrP gene (PrP genotype) of the animals. Despite the widely studied PrP gene polymorphisms worldwide, limited data is available on PrP genotypes of sheep from the African continent. Previously, we have reported six PrP genotypes derived from four different alleles in Red Maasai and Black Herd Persian (BHP), the ARQ/ARQ genotype being more frequent in the Red Maasai than in the BHP sheep. The highly susceptible VRQ allele was not found in any of the sheep breeds; the ARR allele was absent in the Red Maasai or occurred at a low frequency in the BHP. The lack of the highly susceptible VRQ alleles among Tanzanian sheep examined, necessitated further examinations on genetic susceptibility in sheep of the same breeds, but originating from an entirely different part of Tanzania. Consistently, ARQ/ARQ genotype was observed in 88% of Red Maasai and 64% of BHP sheep, ARQ/AHQ genotype was present in 12% in Red Maasai and 36% in BHP. Neither the highly resistant (ARR/ARR), nor the highly susceptible (VRQ/VRQ) genotypes were found. The ARQ and AHQ were the only alleles observed. The ARQ allele constituted 94%, 82% and 67% in the Red Maasai, BHP and cross-bred sheep, respectively. The AHQ constituted 6%, 18% and 33%, respectively. Data reported here, provide additional information on genetic susceptibility of the Red Maasai, BHP and their crosses; they may be helpful in policy formulation for future prevention of scrapie.

The effect of wattle tannin drenches on gastrointestinal nematodes of tropical sheep and goats during experimental and natural infections

SUMMARYIn previous work, administration of a commercial tannin preparation, quebracho, as oral drench was shown to reduce significantly faecal egg counts (FEC) and worm burdens of temperate sheep with experimental Haemonchus contortus infection. In the current work carried out in Morogoro, Tanzania, three separate animal trials were carried out to investigate the effect of drenches of wattle tannin (WT), a similar tannin preparation that is readily available in the tropics, on nematodes of tropical goats and sheep. In the first trial, 36 young Small East African (SEA) goats were experimentally infected with a single dose of mixed nematode larvae and FEC were monitored regularly. On day 30 post-infection (p.i.), the animals were blocked on the basis of their FEC and randomly assigned into three equal groups (n=12). For 3 consecutive days, two groups received low and high doses of drench at a rate of 1·2 and 2·4 g WT/kg bodyweight, respectively, whereas the third group received a placebo drench (i.e. water). All goats were humanely slaughtered on day 42 p.i. and their worm burdens were assessed. Neither FEC nor worm burdens were significantly reduced by the administration of the low or high dose of WT. The second trial had an identical design but two groups (n=14) of growing Black Head Persian (BHP) sheep were used instead. One group received the drench at 1·5 g WT/kg body wt for 3 consecutive days, whereas the other group received a placebo. Unlike in goats, worm burdens and FEC were significantly reduced (P&lt;0·001) by the drench administration. In the third trial, the effect of WT drench against a naturally acquired nematode infestation in a flock of 34 BHP sheep was determined. FEC were examined three times in a 2-week period and the egg counts were used to block the sheep before being randomly assigned into two groups (n=17). The treated group received the drench at 1·0 g WT/kg bodyweight for 3 consecutive days, while the remaining half was given a placebo. The two groups continued to graze together as FEC were being monitored. Results indicated a significant (P&lt;0·001) reduction in egg counts, which remained low for at least 3 weeks after the drench. The current study demonstrated that the WT drench had significant anthelmintic activity against important nematodes in sheep but not in goats, suggesting an existence of species differences between the two hosts. It was concluded that WT drenches could be used in combination with other worm control strategies to reduce or control nematode infections, at least in sheep.

Genotyping of the prion protein (PrP) gene in Red Maasai and Black Head Persian sheep in Tanzania

Susceptibility to scrapie in sheep is largely influenced by four polymorphic amino acid positions of the ovine PrP gene at codons 136, 141, 154 and 171. Genotyping of corresponding DNA polymorphism can be used as a basis for selection decisions. A total of 100 Red Maasai and 79 Black Herd Persian sheep, representative of the widely distributed breeds in Tanzania, were genotyped by real-time PCR. Genomic DNA was extracted from buccal epithelial cells. We report six genotypes derived from four different alleles, with the ARQ/ARQ genotype being more frequent ( p = 0.0081) in the Red Maasai than in the Black Head Persian sheep. Our study also demonstrated higher allelic frequency ( p = 0.00055) of the ARQ in the Red Maasai than in Black Head Persian sheep, while the AHQ allelic frequency was higher ( p = 0.00086) in the Black Head Persian. All the animals were homozygous LL 141. The highly susceptible VRQ allele was not found in any of the sheep breeds examined in this study. Both breeds were genetically low-level resistant to scrapie (NSP3). Due to absence or very low frequency of the ARR allele in the two breeds, selection for genetic resistance to scrapie through an increase of the ARR allele does not seem very relevant. If new breeds of sheep are to be introduced for crossbreeding in Tanzania, care should be taken to avoid import of the VRQ allele. To our knowledge, this is the first study exploring the PrP genotypes in sub-Saharan African sheep and in the Red Maasai and Black Head Persian sheep breeds in particular. The data provide base-line information on genetic susceptibility of the two sheep breeds to scrapie, which may be useful in policy formulation for prevention and future research on prion diseases.

Effect of tanniniferous browse meal on nematode faecal egg counts and internal parasite burdens in sheep and goats

The effect of tanniniferous browse meal on faecal egg counts (FEC) and intestinal worm burdens was investigated in sheep and goats infested experimentally with gastrointestinal nematodes. Initially, leaves of different browse tree species were assayed for condensed tannin (CT) content using a colorimetric method to determine concentration and seasonal variations. The level of CT in the leaves ranged between 58 – 283 g/kg dry matter. Seasonal changes in CT levels were influenced by stage of leaf maturity with peak levels after the wet season in June. Leaves of Acacia polyacantha had the highest tannin concentration and were used to test their anthelmintic effect in goats and sheep infested with the nematodes in two separate feeding trials. In Trial 1 an acacia leaf meal supplement (AMS) was offered at 100 – 130 g/animal/day for 20 days to growing Small East African goats to investigate its effect on FEC and worm burden. Mean FEC and worm burden of the AMS-fed group were respectively 27% and 13% lower than in the control group. Trial 2 was similar to Trial 1 except that AMS was offered for 30 days to growing Black Head Persian sheep at 170 g/animal/day. The sheep receiving AMS showed a slight reduction in FEC (on average 19% lower than the control group) but had no effect on worm burden. The current results substantiated previous reports of a suppressing effect of CT on gastrointestinal nematodes of small ruminants. Although the observed anthelmintic activity of AMS was less than expected, such reductions can have practical epidemiological implications in reducing pasture larval contamination. Further studies are needed under field conditions to evaluate the feasibility of using locally available tanniniferous browse as an alternative to synthetic anthelmintics in reducing worm infestations in small ruminants. South African Journal of Animal Science Vol. 37 (2) 2007: pp. 97-106

Growth and mortality in sheep and goats under high tsetse challenge in Kenya.

Trypanosomosis is a major impediment to livestock production and economic development in those areas of Africa where it is endemic. Although small ruminants appear to perform better than cattle in various agro-ecological zones, the importance of trypanosomosis has not been extensively investigated in these livestock. This study was designed to investigate the prevalence of trypanosomosis in sheep and goats in an endemic area and to evaluate the performance of different breeds under high tsetse challenge and the potential role of chemoprophylaxis in the control of the disease. The results showed that tsetse flies feed readily on small ruminants, and that these animals are susceptible to trypanosomosis. The Small East African goats acquired fewer infections than the Black Head Persian and Dorper sheep used in the study. In both sheep and goats, chemoprophylaxis with isometamidium chloride (Samorin, Rhone Merieux, Annecy, France) was protective, resulting in fewer infections and higher body weight gain. Trypanosomosis caused anaemia in both sheep and goats, and animals whose PCV fell below 15% rarely recovered, even with trypanocidal drug treatment. The peak transmission period was between 1 and 3 months after the peak tsetse fly density, which raises the possibility of effective strategic prophylaxis.

Promising tropical grasses and legumes as feed resources in Central Tanzania III: Effect of feeding level on digestibility and voluntary intake of four grasses by sheep

An experiment was conducted to study the effect of increasing feeding level on digestibility and voluntary intake of four high yielding grasses cut at 6 and 10 weeks. The grasses were fed to Blackhead Persian rams (mean age = 72 weeks; mean weight = 30 kg) at levels of 600, 900, 1200, 1500 and 1800 g of hay per day in a split plot design. The grasses were Cenchrus ciliaris cv. Biloela (CCB), C. ciliaris cv. Gayndah (CCG), Panicum coloratum cv. Bambatsi (PCB) and Chloris gayana cv. Mpwapwa (CGM). In vivo organic matter (OM) digestibility was on average 60%. Among the species compared, CCB and PCB had lower OM digestibility, by 3 units, than CCG and CGM ( P < 0.05), but CGM had lower intakes ( P < 0.05) than the other species by approximately 20%. Samples taken at 10 weeks regrowth had higher neutral detergent fibre (NDF) and lignin contents and lower protein contents and in vitro organic matter digestibility compared to the 6-week cuts. Intake of OM, but not of NDF was also lower ( P < 0.05) for the 10-week cut. The sheep consumed the grasses selectively in favour of the more nutritious parts when offered excess feed. With higher feeding levels, OM digestibility, but not NDF digestibility, was significantly improved ( P < 0.05). Voluntary intakes of all species and stages were also improved by increasing feeding levels ( P < 0.05). The lowest levels of feeding, allowing maximum intakes of the hays, varied between species and stages of maturity. These feeding levels ranged from 900–1500 g of hay per day with refusals between 15.3–50.8% for PCB (6 weeks) and CGM (10 weeks), respectively. From calculations of optimal feeding levels to attain maximum daily nutrient uptake by producing sheep, we recommend early harvesting and feeding of the grasses at levels allowing refusals of at least 30%.

A systems analysis of inter-annual changes in the pattern of sheep flock productivity in Tanzanian livestock research centres

Annual estimates of production traits over a 22 year period (1965–1987) for Black Head Persian sheep (BHP) from Malya and West Kilimanjaro research centres in Tanzania were utilized to analyse variation of flock productivity over time. Principal component analysis indicated major trends in the variation of trait combinations, while cluster analysis was used to identify years with similar patterns in the combination of traits. The paper discusses the historical pattern which is identified. It appears that productivity patterns were only weakly related to ecological changes, but were more strongly related to management factors. The approach and analytical technique employed are recommended as tools in livestock systems diagnostic research.

Comparative water consumption and efficiency in three divergent sheep types

SUMMARYCumulative feed and water intakes and body weights of 30 growing ewe lambs of three different breeds were recorded weekly for 34 weeks between October 1990 and June 1991 at the Experimental Farm of the University of Pretoria. The results were analysed to obtain water efficiencies on both an absolute and metabolic weight gain basis. On an absolute basis, Mutton Merino sheep consumed 145% and Dorper 109% more water than Blackhead Persian sheep. On a metabolic weight gain basis, the corresponding differences were 92 and 66%, respectively. Mutton Merino and Dorper lambs also consumed 69 and 41% more water per kg feed intake than the Blackhead Persians, respectively. Weekly water consumption increased twice as much per 1 °C increase in ambient temperature in the Dorper and Mutton Merino lambs as in the Blackhead Persians. These results suggest that sheep of the Blackhead Persian, and probably also other indigenous breeds, balance their water requirements at a more economical level and would be a more appropriate choice than those breeds currently being managed in sustainable sheep production systems in areas where water availability is limited.

Poultry by-product meal as a substitute for soybean meal in the diets of growing hair sheep lambs fed whole chopped sugarcane

Poultry by-product meal (PBM) was examined as a substitute for soybean meal (SBM) in the diets of tropical hair sheep lambs fed fresh whole chopped sugarcane (WCS). Forty-eight growing crossbred (Barbados Blackbelly x Blackhead Persian) intact ram lambs with a mean initial BW of 13.8 ( ± SD, 0.8) kg were utilized. There were three lambs per pen, group fed and four treatments A, B, C and D where PBM nitrogen replaced 0, 33, 67 and 100% of the nitrogen from SBM in the diet, respectively. All diets were formulated to be iso-nitrogenous (16.0% CP, NPN supplied 28% of the total CP) and iso-caloric 13.9 MJ DE/kg DM. Dry matter intake was ( P>0.05) (A) 0.825, (B) 0.788, (C) 0.743 and (D) 0.800 kg/d/lamb or 3.98, 3.76, 3.79 and 3.72 g/100 g BW; average daily gain ( P<0.05) was 142, 171, 148 and 161 g/d/lamb and feed conversion efficiency (FCE) was 5.86, 4.62, 5.02 and 4.97 kg/kg BW gain, respectively. Lambs fed the 100% SBM diet (A) had lower daily gain ( P<0.05) than those fed the 100% PBM diet (D). Feed cost decreased and income over feed cost increased with increasing levels of PBM nitrogen in the diet. It was concluded that PBM was a useful and cheaper protein substitute for SBM in a WCS-based ration.

Comparative performance of several breeds of Caribbean hair sheep in purebreeding and crossbreeding

The relative merit of the Barbados Blackbelly (BB), West African (WA), Blackhead Persian (BHP), Blenheim Grade (BLG) and Virgin Island White (VIW) breeds of hair sheep was examined as straightbreds and in 2-, 3- and 4-breed combinations. Lamb performance traits studied were birth weight, preweaning average daily gain, weaning weight and survival to weaning at 8 weeks. Purebred WA, BB and BLG lambs were similar in growth, but excelled the other two breeds. Straightbred and 2-breed cross lambs were similar in growth performance; however, 3- and 4-breed crosses were significantly superior in average daily gain and weaning weight. Differences in general combining ability of breeds and reciprocal effects were significant for birth weight only. Differences in maternal ability of BB, WA and BHP ewes were significant for average daily gain and weaning weight, with WA ewes excelling. Three-breed cross lambs sired by WA rams also excelled in growth. BHP lambs or crossbred lambs born to BHP ewes exhibited highest survival to weaning. With respect to ewe performance traits, BB ewes ranked highest in frequency of multiple births, prolificacy, number of lambs weaned and total weight of lamb (s) weaned per ewe lambing, followed by WA, BLG and BHP ewes. Performance of Virgin Island White lambs and ewes was generally inferior to other breeds; however, the data were insufficient to draw definitive conclusions. Crossbreeding did not significantly improve number of lambs weaned or total weight of lamb (s) weaned.