An introductory survey of helminth control practices in south africa and anthelmintic resistance on Thoroughbred stud farms in the Western Cape Province.

Fifty-one per cent of 110 questionnaires, designed for obtaining information on helminth control practices and management on Thoroughbred stud farms in South Africa, were completed by farmers during 2000. The number of horses per farm included in the questionnaire survey ranged from 15 to 410. Foals, yearlings and adult horses were treated with anthelmintics at a mean of 7.3 +/- 3.0, 6.6 +/- 2.7 and 5.3 +/- 2.3 times per year, respectively. An average of 3.4 different drugs were used annually, with ivermectin being used bymost farmers during 1997-2000. On 43% of farms the weights of horses were estimated by weigh band and 45% of farmers estimated visually, while both were used on 7% of farms and scales on the remaining 5%. Doses were based on average group weight on 50% ofthe farms and on individual weights on 46%. Forty-three per cent of farmers performed faecal egg count reduction tests (FECRT). Most farmers rotated horses between pastures and treated new horses at introduction. Faecal removal was practiced on 61% of farms and less than 50% of farmers used alternate grazing with ruminants. Faecal egg count reduction tests were done on 283 horses, using oxibendazole, ivermectin and moxidectin on 10,9 and 5 farms, respectively, in the Western Cape Province during 2001. While the efficacy of oxibendazole was estimated by FECRT to range from 0-88% and moxidectin from 99-100%, ivermectin resulted in a 100% reduction in egg counts. Only cyathostome larvae were recovered from post-treatment faecal cultures.

Sperm viability and morphology of two genetically diverse Merino lines.

Microscopically evaluated sperm parameters, as well as computer-aided sperm motility analysis (CASMA), were used to assess sperm quality and the effect of cryopreservation on ram semen obtained from two genetically diverse Merino lines. These lines were divergently selected on maternal ranking values for multiple rearing ability from the same base population since 1986. Replacements in the high (+) line were preferentially the progeny of ewes rearing >1 lamb per joining. Progeny of ewes rearing <1 lamb per joining was preferred as replacements in the low (-) line. Sperm quality, as assessed by percentages of live, abnormal and acrosome-intact spermatozoa as well as by motility, was independent (P < or = 0.20) of line, time of sampling and their interaction in ejaculated samples obtained from the eight rams used as sires in 1995. Sperm quality of frozen-thawed samples was adversely affected (P < or = 0.01) by cryopreservation and thawing at 35 degrees C for 30 s relative to fresh ejaculated samples. No consistent differences between lines were found in epididymal sperm samples obtained from 12 slaughtered rams (6 from each line). The adverse effect (P < or = 0.05) of cryopreservation and thawing at 35 degrees C for 30 s on sperm viability and motility was also demonstrated for these samples.

The application of a selenium fertiliser for the correction of marginal deficiencies in grazing sheep.

A commercial fertiliser, consisting of a poorly soluble barium selenate core with a coating of highly soluble sodium selenite, was evaluated in 2 trials for the provision of selenium (Se) to grazing sheep. The fertiliser was administered at a level of 1 kg per hectare to 3 of 6 kikuyu paddocks during 1995 and 1996 in Trial 1, while the other paddocks were left untreated. The Se status of SA mutton merino ram lambs, as reflected by whole blood, liver and kidney Se concentrations, was elevated (P < 0.01) for at least 5 months after application of the fertiliser. Whole blood and liver Se concentrations of animals grazing unfertilised control paddocks were indicative of a subclinical Se deficiency at times (<100 ng Se/ml whole blood and <300 microg Se/kg liver dry matter). In Trial 2, 4 of 7 paddocks on which an oat fodder crop was established were treated with the Se fertiliser during 1995 and 1997. The remaining 3 paddocks were left unfertilised as controls. Groups of 10-15 pregnant SA mutton merino ewes were introduced to these paddocks within 2 weeks of parturition. These ewes and their progeny utilised these paddocks for a mean (+/- SD) period of 41 +/- 8 days after parturition. The whole blood Se concentrations of these ewes and their offspring were elevated (P < 0.01) relative to their contemporaries utilising control paddocks. No suggestion of a subclinical Se deficiency was discernible in animals grazing control paddocks, although whole blood Se levels approached 100 ng Se/ml during 1997. The application of Se fertiliser did not result in improvements in ewe reproduction or lamb growth. There was a suggestion of an improvement (P = 0.21) in mean (+/- SE) lamb survival on paddocks receiving Se fertiliser compared to control paddocks (71.5 +/- 4.6% vs 62.2 +/- 5.3% respectively).

The effect of cryopreservation on the survivability, viability and motility of epididymal African buffalo (Syncerus caffer) spermatozoa.

The effect of cryopreservation on the viability and motility of epididymal African buffalo spermatozoa was studied in samples obtained from 17 and 13 animals in 1995 and 1996, respectively. Cryopreservation significantly reduced the viability and motility of the epididymal spermatozoa. The average percentage of live (+/- SE) spermatozoa declined significantly from 90.4 +/- 2.0% (1995) and 84.4 +/- 1.1% (1996) in fresh epididymal samples, to 57.0 +/- 2.0% and 56.3 +/- 1.1%, respectively, in frozen-thawed samples. The acrosomal integrity (+/- SE) of spermatozoa declined from 89.3 +/- 2.3% (1995) and 93.3 +/- 2.2% (1996) to 50.2 +/- 2.3% and 37.5 +/- 2.2%, respectively. In 1995, this effect was largely associated with the thermal equilibration prior to cryopreservation.

The effect of dietary protein on reproduction in the mare. V. Endocrine changes and conception during the early post partum period.

Pregnant Anglo-Arab and Thoroughbred mares (n = 24) were divided randomly according to age and breed into 4 groups of 6 mares each from approximately 6 weeks before their expected foaling date. Diets received by the 4 groups varied in essential amino-acid and total protein contents. Serum progestagen, FSH and LH concentrations were determined from the day of parturition until foal heat and during the 1st oestrous cycle following foal heat. Serum progestagen, FSH and LH concentrations did not differ between the treatment groups. Progestagen concentrations were high (mean = 7.0: 5.2-16.4 ng/ml) at parturition but decreased rapidly within 48 h. As progestagen concentrations decreased LH concentrations increased from Days 3-6 post partum to reach maximum values at, or the day after ovulation. FSH concentrations declined 3-4 d after parturition and increased 2-3 d before ovulation at foal heat. The duration of elevated progestagen concentrations during the luteal phase of the subsequent oestrous cycle affected the interovulatory period. A 12-14 d FSH cyclical releasing pattern occurred. Season/photoperiod affected the resumption of normal oestrous cyclicity during the post partum period. The duration of the 1st oestrous cycle after foal heat in mares fed a low-quality protein diet showed a greater range (13-30 d) compared to mares fed a high-quality protein diet (18-26 d).

The effect of dietary protein on reproduction in the mare. VI. Serum progestagen concentrations during pregnancy.

Sixty-four Thoroughbred and Anglo-Arab mares aged 6-12 years were used, of which 40 were non-lactating and 24 lactating. Foals from these 24 mares were weaned at the age of 6 months. Non-lactating and lactating mares were divided into 4 dietary groups each. The total daily protein intake and the protein quality (essential amino-acid content) differed in the 4 groups of non-lactating and 4 groups of lactating mares. The mares were covered and the effect of the quantity and quality of dietary protein on serum progestagen concentrations during pregnancy was studied. A sharp decline in serum progestagen concentrations was recorded in all dietary groups from Days 18 to 40 of pregnancy, with some individual mares reaching values of less than 4 ng/ml. Serum progestagen concentrations recorded in some of the non-lactating mares on the low-quality protein diet increased to higher values (p < 0.05) than those of mares in the other 3 dietary groups at 35-140 days of pregnancy. A similar trend was observed for the lactating mares on a low-quality protein diet at 30-84 days of pregnancy. No such trends were observed in any of the other dietary groups. High-quality protein supplementation increased serum progestagen concentrations during the 1st 30 days of pregnancy. Lactation depressed serum progestagen concentrations until after the foals were weaned.

The effect of dietary protein on reproduction in the mare. VII. Embryonic development, early embryonic death, foetal losses and their relationship with serum progestagen.

Sixty-four Thoroughbred and Anglo-Arab mares aged 6-12 years were randomly allocated to 4 dietary groups and fed diets that differed in the total protein content and quality (essential amino-acids). Forty mares were non-lactating and 24 lactating. Eight mares were withdrawn from the investigation owing to injuries or gynaecological pathology. An overall conception rate of 94.6% and a foaling rate of 80% was achieved. Five of 14 (35.7%) mares (Group 1) fed a low-quality protein diet suffered from early embryonic loss before 90 days of pregnancy compared to 3 of 41 (7.3%) mares in the remaining groups that received the higher-quality protein in their diets. Serum progestagen concentrations of mares in Group 1 that suffered foetal loss were indicative of luteal function insufficiency during the 1st 40 days post-ovulation. Non-lactating mares in all 4 groups gained on average approximately 30 kg in mass during the 90 days before the breeding period. Lactating mares in Group 1 (low-quality protein) lost on average 25 kg in mass during lactation, with no weight loss observed among the lactating mares in the other 3 groups. No difference in the diameter of the embryonic vesicle was found between dietary groups until Day 35 of pregnancy.

The effect of dietary protein on reproduction in the mare. I. The composition and evaluation of the digestibility of dietary protein from different sources.

Four rations that differed in their crude protein and essential amino-acid content were compiled. Digestibility of the crude protein and essential amino-acid contents were determined biologically in a feeding trial using 4 Anglo-Arab stallions. Their respective daily diets were: Diet 1:2 kg cubes, 5 kg tef hay (Eragrostis tef); Diet 2:2 kg cubes, 5 kg lucerne hay (Medicago sativa); Diet 3:2 kg cubes, 5 kg tef hay, 200 g fishmeal; Diet 4:2 kg cubes, 5 kg lucerne hay, 200 g fishmeal. The concentrations of the amino-acids threonine, iso-leucine, leucine and arginine were increased in the total ration when lucerne hay replaced the tef hay while fishmeal supplementation increased the methionine and lysine contents, which provided a wide-range of concentrations of digestible amino-acids in each of the 4 rations.

The effect of dietary protein on reproduction in the mare. II. Growth of foals, body mass of mares and serum protein concentration of mares during the anovulatory, transitional and pregnant periods.

The effect of 4 different diets, in terms of protein quantity and quality, on total serum protein (TSP), albumin and globulin was investigated. Non-pregnant mares that were not lactating (n = 36), pregnant mares that had foaled (n = 24) and their foals (n = 24) were used in this study. Daily total protein intake had no effect on blood protein concentrations in the mares. Total protein intake and quality (available essential amino-acids) did affect the body mass of mares during lactation. When mares were fed the minimum recommended (National Research Council 1989) total daily protein, foal mass decreased by approximately 25% at weaning compared to the foals whose dams were on a higher level of protein intake. The TSP concentrations of foals at birth were on average 10 g/l lower than those of the mares. Albumin concentrations of foals during the first 60 days of life were on average 2-3 g/l lower than those of the mares. Globulin concentrations of foals were approximately 5 g/l lower than those of mares at weaning.

The effect of dietary protein on reproduction in the mare. III. Ovarian and uterine changes during the anovulatory, transitional and ovulatory periods in the non-pregnant mare.

In the main experiment the total daily protein intake and quality (essential amino-acids) was varied in 4 groups of mares. The incidence of oestrus in mares during the transitional period was unaffected by protein nutrition. Ovarian activity, as evaluated by follicular development and size of the ovaries, was affected. Mares that received low-quality protein (Groups 1 and 2) had a higher number of smaller follicles (< 10 mm) that developed during the transitional period compared to mares on a high-quality protein intake (Groups 3 and 4). The mares that received the high quality protein ovulated 2-3 weeks earlier in the breeding season in a synchronised period of 4-5 weeks compared to a period of 6-8 weeks in Groups 1 and 2. The duration of the subsequent oestrous cycles was not affected. There was no difference in the diameter of the largest follicle of mares between groups on the day before ovulation. In a separate experiment, 5 maiden Anglo-Arab mares, 4-5 years of age, were slaughtered at different stages during the anovulatory, transitional and ovulatory periods of the breeding cycle. The morphology of the ovaries and uteri of these mares was described and photographed for use as guidelines when comparing ovarian changes and follicular activity of mares.

The effect of dietary protein on reproduction in the mare. IV. Serum progestagen, FSH, LH and melatonin concentrations during the anovulatory, transitional and ovulatory periods in the non-pregnant mare.

The effect of total protein intake and protein quality on the serum concentrations of certain reproductive hormones during the anovulatory, transitional and ovulatory periods were studied in 36 Anglo-Arab mares. High-quality protein stimulated FSH and LH production during the late transitional period. Serum progestagen and melatonin concentrations were unaffected by the quality of protein nutrition during the anovulatory period. Mares receiving high-quality protein exhibited a 10-14-day cyclical pattern of FSH release approximately 4-6 weeks earlier than the mares fed the lower-quality protein diet, and also ovulated 3-4 weeks earlier than the mares on the lower-quality protein diet. Progesterone concentrations during the 1st oestrous cycle after the anovulatory period were unaffected by protein quality in the diet.

The effect of selenium supplementation during the early post-mating period on embryonic survival in sheep.

The effect of selenium (Se) supplementation of ewes with blood Se concentrations ranging between 100-200 ng/ml on embryonic survival during the early post-mating period (days 15-35) was studied in 4 trials. In the 1st 2 trials 137 ewes were used in 1991 and 118 in 1992. After being mated as a single flock, these ewes were stratified randomly into 3 groups. One group served as a control, the 2nd was injected with 1 ml Deposel (containing 50 mg Se as Ba selenate) and the 3rd group injected with 1 ml containing 1 mg Se as Na selenite. During 1991, supplementation was administered immediately after the mating period. It was postponed by 14 days in 1992. Parenteral Se supplementation reduced (p < 0.10) the number of ewes that lambed by > 19% during 1991 but not during 1992. The number of ewes producing twins was unaffected. In Trials 3 and 4 there was a consistent indication that parenteral Se supplementation of pregnant ewes between 15-35 days after mating resulted in a reduced (22-40%) embryonic survival rate, although significant (p < or = 0.10) differences were only observed after the pooling of treatments receiving parenteral Se supplementation. Drenching of ewes with 50 mg Se as Na selenite resulted in a similar tendency. Biochemical appraisal of the blood, kidney and liver Se status of ewes failed to reveal toxic levels. The possible mechanisms involved in impaired embryonic survival are unclear. Supplementation of ewes during the 1st month of pregnancy with parenteral Se preparations is not recommended.

Parenteral copper and selenium supplementation of sheep on legume-grass pastures: biochemical and production responses in lambs to maternal treatment.

Liver and kidney copper (Cu) and selenium (Se) concentrations were studied over a 7-month period after parenteral supplementation using Cu heptonate and barium (Ba) selenate in 44 8-month-old South African (SA) Mutton Merino wethers. Responses in plasma Cu and blood Se concentrations, as well as fecundity were also measured in a breeding flock of SA Mutton Merino ewes for 3 consecutive years. The effect of maternal supplementation with Cu and Se was assessed in terms of biochemical parameters and production responses in 654 lambs produced by these ewes. Parenteral treatments with Cu and Se raised liver and kidney concentrations (P < or = 0.05) for up to 7 months in wethers under conditions where liver Cu and Se respectively declined to concentrations below 30 mg/kg DM and 300 micrograms/kg dry matter (DM) in spring. Plasma Cu concentrations of breeding ewes which received Cu heptonate were increased (P < or = 0.05) by 18% relative to the control group in which concentrations declined to 91 micrograms/dl during late pregnancy. Blood Se concentrations of control ewes exceeded 200 ng/ml, and were unaffected by parenteral Se supplementation. Survival of progeny of Cu heptonate treated ewes tended (P < or = 0.10) to be improved by 13% (0.68 vs 0.60). This tendency was accompanied by generally higher (P < or = 0.10) plasma Cu concentrations of these lambs relative to control lambs at 10 - 20 and 45 - 55 d of age. Lambs of Cu supplemented ewes that died prior to weaning, had higher (P < or = 0.05) liver Cu concentrations than control group contemporaries.(ABSTRACT TRUNCATED AT 250 WORDS)

An assessment of the toxicity of parenteral treatment with copper EDTA and copper heptonate in sheep.

The toxicity of 2 parenteral copper (Cu) supplements was investigated. Di-sodium copper ethylene diamino tetra acetate (Cu EDTA) and Cu heptonate were administered to sheep (n = 9) by a single subcutaneous injection at a concentration of 0,2, 1 and 2 mg Cu/kg each (Trial 1.) Nine sheep were untreated and served as controls. The same treatments were applied to 2 sheep each (Trial 2) with the addition of 3 mg Cu/kg live body mass as Cu heptonate, and Cu heptonate administered intravenously at rates of 0,2, 0,4 and 0,6 mg Cu/kg live body mass. In Trial 1, 67% of the sheep treated with Cu EDTA at 2 mg Cu/kg live body mass died within 3 to 17 d after treatment, while no mortalities occurred in sheep where Cu heptonate was administered at the same dosage rate and even at 3 mg Cu/kg live body mass (P < or = 0,01). Post-mortem examination suggested acute Cu toxicity in all cases. Liver Cu concentrations were markedly increased (P < or = 0,05) by both supplements in groups of 3 treated sheep slaughtered over a 3-month period compared to control animals. The liver Cu concentrations of sheep that succumbed to Cu toxicity were within the normal range of 100 to 450 mg/kg DM. Results from Trial 2 suggested that the 2 sheep treated with 2 mg Cu/kg live body mass as Cu EDTA, experienced a haemolytic crisis between 5 and 11 d after treatment, resulting in the death of one of these sheep. The haemolytic crisis was characterised by a severe decrease in haemoglobin concentration and haematocrit.(ABSTRACT TRUNCATED AT 250 WORDS)

Production responses of sheep supplemented with copper, cobalt and selenium on kikuyu ryegrass pastures.

The copper (Cu) and selenium (Se) status of SA Mutton Merino ewes grazing kikuyu-ryegrass pastures was investigated by analysing blood and liver samples. The response of ewes to oral supplementation with Cu, Cobalt (Co) and Se as single elements, or in 4 combinations were simultaneously assessed in a 2 x 2 x 2 factorial experiment. Pastures grazed were low in Cu (less than 5 mg Cu/kg DM) except for the summer months, while pasture Se concentrations remained at concentrations less than 0,03 mg Se/kg DM for almost the entire period. Plasma Cu concentrations remained in excess of 80 micrograms/dl until pasture Cu concentrations decreased below 5 mg/kg DM. Blood Se concentrations generally reflected liver Se concentrations. Supplementation of ewes with 5 g Cu oxide needles (Embamin Copper LA, Rhône Poulenc) markedly increased (P < or = 0,01) hepatic Cu and plasma Cu concentrations. The monthly drenching of ewes with 5 mg Se as sodium selenite elevated blood Se concentrations to normal levels in excess of 100 ng/ml while ewes not supplemented with Se had blood Se concentrations indicative of a deficiency (50-100 ng/ml). Supplementation of ewes with Cu and Se elevated (P < or = 0,05) concentrations of these trace elements in the plasma and blood of their progeny. Supplementation of ewes with Cu and Se resulted in respective improvements (P < or = 0,05) of 5,3 and 4,8% in live mass during lactation, compared to contemporaries which did not receive either Cu or Se.(ABSTRACT TRUNCATED AT 250 WORDS)

The bent-leg syndrome in sheep. II. Association with genetic markers.

Comprehensive blood typing (17 factors) and electrophoretic protein markers (haemoglobins, transferrins and albumins) were determined on S.A. Mutton Merino sheep (n = 275). The frequencies of these genetic markers were compared between ram lambs with normal and ram lambs with bent-legs and in a second trial between non-affected ewes and their lambs and ewes and lambs which were considered to be carriers of genetic factors resulting in the bent-leg syndrome. The presence of blood factors 2, 3 and 13 and the absence of factors 8, 10 and 17 is possibly linked to the bent-leg syndrome. Although the frequencies of TFA and TFD alleles were higher in the suspected carrier animals than non-affected animals, no definite linkage to the bent-leg syndrome was found. Haemoglobin and albumin type showed no correlation with the bent-let syndrome.

The bent-leg syndrome in sheep. I. The effect of pregnancy and age of the ewe on concentrations of plasma minerals.

The effect of age of the ewe and pregnancy on concentrations of plasma calcium, phosphorus and magnesium and its relationship to the bent-leg syndrome in lambs, were investigated. This study included Merino ewes (n = 74), Dohne Merino ewes (n = 127), S A Mutton Merino ewes (n = 123) and S A Mutton Merino lambs (n = 145). Over a period of 8 years, 52 S A Mutton Merino ram lambs out of a total of 602 ram lambs weaned (8,6%), developed the bent-leg syndrome compared to the 2 ewe lambs out of 591 ewe lambs (0,3%) weaned. It was found that both the age of the ewe and pregnancy had no contributing effect in the development of this syndrome. The ewes of which the offspring developed the bent-leg syndrome, had an inverse plasma Ca:P ratio. Approximately 15% of the S A Mutton Merino ewes which gave birth to offspring which developed the bent-leg syndrome, had more than one lamb which developed this condition over the past 8 years. It is suggested that these ewes are carriers of certain genetic factors which can cause excessive phosphorus absorption. No differences in the concentration of plasma calcium, phosphorus and magnesium were found between ewe and ram lambs.

The influence of experimentally induced copper deficiency on the fertility of rams. I. Semen parameters and peripheral plasma androgen concentration.

The influence of molybdenum and molybdenum plus sulphate-induced copper deficiencies on semen quality and peripheral plasma testosterone concentrations in South African Mutton Merino rams was investigated. All animals received an identical ration, supplemented with molybdenum in one group (M) and molybdenum plus sulphate in another (MS) while the control group (C) received additional copper supplementation. After almost a year on these rations, rams in Group MS produced ejaculates of lower volume, lower sperm concentration, poorer sperm motility and morphology than rams of the other 2 groups. The fructose concentration in the ejaculates of group MS rams was also lower than that of rams in the other groups. Peripheral plasma testosterone concentrations in Group MS were lower than in Groups C or M. Liver copper concentrations and clinical signs were consistent with a severe copper deficiency in Group MS and a mild deficiency in Group M. After the copper deficiency was reversed, the above parameters reverted to normal. It was concluded that an experimentally induced copper deficiency produced reversible impairment of testicular function in rams.

The influence of experimentally induced copper deficiency on the fertility of rams. II. Macro- and microscopic changes in the testes.

The macro- and microscopic changes of the testes caused by molybdenum as well as a molybdenum plus sulphate induced copper deficiency were investigated in S.A. Mutton Merino rams. Judged on testes measurements, the testes development of rams suffering from a severe copper deficiency was slower (P less than or equal to 0.05) when compared with rams in the control group. Histological examinations of the testes of the rams which suffered from a severe copper deficiency revealed that the seminiferous tubules were less developed and less active than those of the control group. This was mainly due to the inactivity of the Sertoli cells. Where rams suffered from a copper deficiency, the Sertoli cells contained only a small volume of cytoplasm. The typical fingerlike cytoplasmic evaginations of the Sertoli cells into the lumen of the seminiferous tubules were absent while the nuclei of these cells were darkly stained, in some cases even pycnotic. Spermatocytogenesis was normal because primary spermatocytes with dark stained thread-like chromatin were observed in most of the seminiferous tubules. The process of spermiogenesis (metamorphic phase) did not take place. This can be accounted for by the inactivity of the Sertoli cells.

Breed differences in plasma calcium, phosphorus and magnesium concentrations of Merino, Dohne Merino and S.A. Mutton Merino sheep with relation to the bent-leg syndrome.

Plasma calcium, phosphorus and magnesium concentrations were determined in ewes and their single and twin lambs from birth for 120 days in Merino, Dohne Merino and South African Mutton Merino sheep. Mineral concentrations as well as the plasma calcium: phosphorus ratio were compared between breeds. Throughout the experimental period, plasma calcium and phosphorus concentrations were higher in both single and twin lambs than in the ewes of all 3 breeds. No breed differences in plasma calcium concentrations were found. Animals of the S.A. Mutton Merino breed had significantly higher (P less than 0.05) plasma phosphorus concentrations than the other 2 breeds. The plasma Ca:P ratio in the Merino and Dohne Merino ram lambs was approximately 1.1:1 and in the S.A. Mutton Merino 0.9:1. This converse plasma Ca:P ratio found in both the S.A. Mutton Merino ewes and lambs is believed to result in an induced plasma ionised calcium deficiency which leads to improper calcification of bone. This is believed to be a contributing factor in the bent-leg syndrome. No difference was recorded in body mass between ram lambs suffering from the bent-leg syndrome and unaffected ram lambs. Plasma magnesium concentrations were not affected by breed or age of the animals.