Blackhead Persian Research Articles

Alternative use of Karakul sheep for pelt and lamb production in Botswana. I. Reproduction and growth performance

Performance data of 9800 Karakul, Namaqua Africander, Blackhead Persian sheep and their various crosses were collected from July 1986 to September 1987 in the Southern Kalahari desert of Botswana. Karakul lambs may be used either for pelt (Persian lamb) or for meat production. The purpose of this study was to assess the overall productivity of Karakul sheep and their crosses with local mutton breeds for producing both pelts and lambs for meat. Annual number of lambings per ewe averaged 1.39, litter size 1.007. In flocks with predominantly Karakul breeding, 43% of Karakul lambs were slaughtered for pelt production. Body weight of ewes in the first month post-partum was 40.8 kg, lamb weight at 150 d was 27.4 kg. Neither genotype nor management class had a significant influence on the annual number of lambings per ewe, or body weight of ewe and lamb. Season of birth, lambs being pelted or reared, and flock-within-management class had significant effects on these traits. During the study period, 13.2% of lambs were recorded as having died, 6.4% were home slaughtered, 18.0% sold and 8.0% of all disposals could not be traced; for adult sheep, the corresponding rates were 4.3%, 3.7%, 12.5% and 5.6%, respectively. Average flock productivity was estimated to be 27.7 kg lamb per ewe and year, 0.67 kg lamb per kg ewe and year, and 1.71 kg lamb per kg 0.75 ewe and year.

Effects of replacing sunflower seed cake with Crotalaria ochroleuca hay on feed intake, digestibility and growth rate of grazing sheep

Sixteen Blackhead Persian sheep were fed four rations containing four levels of Crotalaria ochroleuca (“marejea”) hay at 0, 15, 30 and 45% and sunflower seed cake (SSC) at 0, 10, 20 and 30%, as a supplement to grazing 8 h/d. The four supplemental rations were 30% SSC (T 1), 20% SSC+ 15% marejea (T 2), 10% SSC+30% marejea (T 2) and 45% marejea. In addition, the animals received Rhodes grass hay, maize bran and mineral mixture. Replacement of concentrates (sunflower seed cake and maize bran) with marejea hay reduced ration dry matter and crude protein digestibilities from 63.7 to 54.5% and from 72.6 to 59.4%, respectively ( P < 0.05). Dry matter, organic matter and crude protein intake (g/d) decreased as hay level increased ( P < 0.05). Growth rates decreased from 84.4 to 56.7 g/d ( P < 0.05) between T 1, T 2, T 3 and T 4 as level of marejea hay increased. There was no significant difference ( P > 0.05) between rations containing marejea. Daily N retention decreased from 6.4 to 5.3 g/d as level of marejea substitution for sunflower seed cake increased. Controls (T 1) had high ( P < 0.05) retained levels of N. It was concluded that marejejea indigenous legume that grows wild in Tanzania can be used to replace sunflower seed cake in rural areas where the cake is not available and labour is cheap.

Comparative performance of Landim and Blackhead Persian sheep in Mozambique

Larger litter sizes of Landim sheep (1.38 lambs per parturition) compared to Blackhead Persian (BHP) (1.00) and BHP X Landim (1.00), and similar parturition intervals in each genotype (342 days) resulted in greater annual output of young in the Landim (1.71) than in BHP (1.17) or in BHP x Landim (1.25). Weights of all three genotypes were similar at birth (2.5 kg), at 90 days (12.5 kg), at 150 days (15.0 kg) and at 365 days (28.1 kg). Breed did not affect the death rate at any of 10 days (4.9%), 30 days (6.7%), 90 days (11.9%) or 150 days (19.6%) of age. Output of weaned lambs per breeding ewe per year was slightly (P< 0.1) higher in crossbred (23.3 kg) than in Landim (19.7 ) or BHP (19.4 kg) but output per kg live weight of ewe (488 g) and per kg 0.73 live weight of ewe (1.36 kg) did not differ among the genotypes. Year, season, type of birth, sex and ewe age significantly influenced most traits. Overall performance of Landim sheep was not different to that of the BHP indicating little if any advantage in using BHP. Landim sheep have large litter sizes in comparison to other African indigenous breeds and could themselves be used to improve reproductive performance of other strains of sheep.

The nutritive value of ensiled forages cut at three stages of growth

Twelve male adult Black Head Persian sheep were used in a digestibility and feed intake trial to evaluate maize, guinea grass and jaragua grass silages. The forages were cut at the pre-anthesis, anthesis and post-anthesis stages of growth. Dry matter (DM), pH and ammonia nitrogen of the silages were also determined. Maize silage had a lower mean pH than the 2 grass silages. The organic matter digestibility (OMD), crude protein digestibility (CPD) and crude fibre digestibility (CFD) were higher in maize silage than in the 2 grasses. Guinea grass silage had a significantly ( P < 0.01) higher OMD, CPD and CFD than jaragua grass silage. Silages made from herbage harvested at the pre-anthesis stage had a significantly ( P < 0.01) higher OMD, CPD and CFD than those made from herbage harvested at the post-anthesis stage of growth. Maize silage was superior at all stages of growth, except at pre-anthesis, to the 2 grass silages. Both jaragua and guinea grass produced good silage when herbage was harvested at the pre-anthesis and anthesis stages of growth.

The influence of breed on the susceptibility of sheep to Haemonchus contortus infection in Kenya

The relative resistance of six breeds of sheep to Haemonchus contortus infection was investigated under field conditions on two stations situated in a semi-arid zone in Kenya. As judged by faecal egg counts, monitored throughout a two-year period, it was found that there were consistent differences between the breeds. The breeds studied in order of increasing susceptibility were Red Masai, Blackhead Persian, Merino, Dorper, Corriedale and Hampshire. Post mortem findings confirmed that the differences in faecal egg count were related to the establishment of worms rather than larval inhibition or the suppression of worm egg production. There was also evidence that the Red Masai showed self-cure more frequently than the other breeds.

Phagocytosis of Erythrocytes and Leucocytes in Sheep Infected with Trypanosoma congolense (Broden 1904)

Observations on the haematology and histopathology of T. congolense infection in Blackhead Persian sheep provided evidence of erythrocyte and leucocyte phagocytosis on a large scale throughout the reticuloendothelial tissues. It is postulated that this phenomenon contributed substantially to the anaemia that developed in the course of the disease and might have been the prime factor. Possible causes of this phagocytic activity include (i) the coating of cells with parasitic antigen, (ii) the production of defective cells and (iii) an auto-immune reaction.

Partition of nitrogen in the urine of African sheep given a variety of low-protein diets

1. Sixteen foods, made up with differing proportions of roughage and concentrates and ranging in crude protein content from approximately 2·6% to 10·0%, were each offeredad libitumto Blackhead Persian wether sheep. The nitrogen balance of the sheep and the distribution of nitrogen in the urine were measured.2. Urinary nitrogen excretion decreased with the digestible nitrogen intake. There was a highly significant (P&lt; 0·01) positive correlation between either excretion of urea or of allantoin and digestible nitrogen intake.3. The amount of creatinine excreted varied little with diet but was directly related to the body weight of the sheep.4. For 8 diets, hippurate excretion by the sheep was directly related (P&lt;0·01) to intake of digestible nitrogen, while a significant (P&lt;0·05) positive correlation between the same measures was found for the other 8 diets.5. It is suggested that with certain types of diets the excretion of either nitrogen, urea or allantoin in the urine may be useful indicators of digestible nitrogen intake of low-protein diets by sheep.

Effects of various low protein diets on the distribution of ruminal nitrogen and on the nitrogen required for maintenance of African sheep

1. Four groups of diets made up with differing proportions of roughage and concentrates were each givenad lib. to 4 Blackhead Persian wether sheep. The four diets in each group contained approximately 4, 6, 8 and 10% crude protein. The distribution of nitrogen in the rumen at various times after feeding and the nitrogen balance of the sheep were measured.2. Total N and ammoniacal N content of the rumen liquor were both closely related to the N content of the diet. Diurnal changes in the concentrations of these components were most marked with the diets which had the highest concentration of protein, and consisted of rapid increases after feeding followed by declines later in the day. Each group of diets produced characteristic patterns of change and these changes appeared to be related to the proportion of concentrates in the diet.3. With sheep given poorly digested veldt grass, very low in protein, levels of ammonia in the rumen were unusually high. This effect was thought t o be due to the recycling of urea and its conversion to ammonia in the rumen.4. The amounts of digestible N required by the sheep for N equilibrium differed between groups of diets. High apparent requirements of digestible N were associated with relatively high ruminal ammonia levels, but the latter were not considered to be the cause of high requirements.5. On all groups of diets, sheep were in N equilibrium only when their intakes of total digestible nutrients (TDN) were adequate for maintenance. This indicates that the protein requirement for maintenance was a function of protein content and TDN content of the diet and the effect of these factors on voluntary intake of TDN.

Volatile fatty acids in the rumen of African sheep given a variety of low-protein diets

SUMMARY1. Total concentrations of volatile fatty acids and molar proportions of acetic, nrooionic and butyric acids were determined in the rumen of Blackhead Persian sheep given sixteen low-protein diets.2. Total concentrations of acids ranged from 2·89 to 9·33 millimoles/ 100 ml. of rumen liquor. Both digestibility and protein content of the ration had a significant effect on the concentration of volatile fatty acids in the rumen liquor. Protein content of the diet probably influenced the latter through controlling the rate of ruminal fermentation.3. Molar proportions of acetic acid varied from 59·7% to 69·3%, of propionic acid from 21·2% to 29·6%, and of butyric plus higher acids from 7·6% to 16·3%. Protein content of the diet had no significant effect on the composition of the acid mixture, but organic matter digestibility was inversely related to the proportion of acetic acid.4. The fermentation in the rumen of Blackhead Persian sheep, as judged by the volatile fatty acids produced, appears to be similar to that found in European breeds of sheep.

The Coat of Sheep

THE letter under this title, by Prof. J. Cossar Ewart, in NATURE of Mar. 19, contains some observations so divergent from those we have made here that it seems desirable to contrast the two. He remarks: “From an investigation which has been in hand for some time on the structure of the fibre forming the coat of sheep, it has been ascertained that in sheep, as in man, the first coat consists entirely of simple pithless fine-wool fibres.” In the course of investigations on South African sheep and wool, I have procured a fairly complete series of foetuses of the Merino, blackhead Persian, Afrikander, and Karakul, as well as of the Angora goat; and in each case microscopic sections have been made of the different stages in the development of the hair and wool. In view of the statement that “the first coat consists entirely of simple pithless fine-wool fibres,” a re-examination has been made of all this material.