Browsing by Author "Lishman, Arthur William."

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Attempts to improve the yield of bovine blastocysts by incorporating insulin, selenium and transferrin in the In Vitro system.
(1996) Bowles, Chloe Melissa.; Lishman, Arthur William.
To produce an embryo via in vitro maturation, in vitro fertilization and in vitro culture methods it is vital to obtain consistent results and at the same time a large number of bias to cysts from the immature oocytes collected, especially when only a small pool of these oocytes are available. The aim of the present investigation was to improve maturation rates, fertilization rates and blastocyst production rates by adding insulin (10 µg/ml), selenium (10 ng/ml) or transferrin (10 µg/ml) to the media. These were added individually or in different combinations and a complete randomised block design was set up to account for block and day effects. It was hypothesised that each treatment would improve maturation and fertilization rates and blastocyst production rates. It was found that of the treatments added to the maturation medium, Selenium at 10 ng/ml improved maturation percentages (80.4% vs 61.8%) and also increased fertilization percentages (68.0% vs 58.4%) and the number of bias to cysts produced (24.6% vs 11.5%). None of the treatments had a beneficial effect on fertilization rates or on blastocyst production rates when added to the fertilization medium. The treatments added to the culture medium showed that Transferrin at 10 µg/ml or Transferrin in combination with Insulin and Selenium increased the percentage of bias to cysts produced by in vitro culture methods (35.3% and 31.5% vs 18.7%). The addition of Transferrin also increased the percentage of bias to cysts that hatched (21.9% vs 14.2%) showing an improvement in the viability of the blastocysts produced. It is recommended that the maturation medium should include Selenium at 10 ng/ml. The fertilization process should have none of the investigated substances added to it and the culture medium should include Transferrin at 10 µg/ml. This combination should optimize the number of viable blastocysts that are produced in a bovine in vitro system.
Capacitation of Nguni semen for in vitro fertilization of bovine oocytes.
(1995) Durrans, Lesley Jane.; Lishman, Arthur William.
In vitro maturation, fertilization and culture is a technique which is increasingly utilised in the animal science industry for embryo production. However, optimal conditions for in vitro maturation, fertilization and culture have not been clearly defined and much research is being done to improve this situation. If these techniques are to be valuable in the production of large numbers of animals in short periods, they must be efficient and reliable. The first part of this investigation aimed to produce comparable rates of fertilization from each of 5 Nguni bulls tested in an in vitro fertilization trial. It was hypothesised that each bull would respond favourably to one or more of the treatments tested. A complete randomised block design was set up to account for block and day effects. A total of 2422 cumulus-oocyte complexes were matured and fertilized with swim-up separated frozen-thawed Nguni semen incubated for 1 min in Ca-ionophore A23187 (0.1, 0.2 or 0.4 µM) or for 15 min in heparin (0.05, 10 or 25 µg/ml). Controls for parthenogenesis and capacitation or acrosome reaction in the fertilization medium were included. Presumptive zygotes were transferred to CR1aa medium and supplemented with 10% and S% FCS on days 4 and 7 post-insemination, respectively. Bull performance was assessed using four criteria: embryo cleavage, a score based on a cleavage index (Score 1; minimum -1, maximum 6) and one which gave greater weight to morulae and blastocysts (Score 2; minimum -1, maximum 10) and blastocyst production. Day effects were highly significant (P<0.001). Parthenogenetic activation of 31.6% of oocytes occurred. Depending on the bull used, cleavage rates (%±s.e.m.) varied from 29.S±2.2 to 40.6±2.6, Score 1 from 0.30±0.07 to 0.6S±0.07, Score 2 from 0.30±0.07 to 0.72±0.08 and % blastocysts from 0.6±0.6 to 4.8± 1.1. Treatment did not significantly affect performance and there were no bull x treatment interactions. However, bull differences in performance were observed. The IVF system employed was not stable and did not produce repeatable results. It was concluded that treatment concentrations tested may have been too low or, alternatively, that treatment effects were being masked by a factor influencing the IVF system more strongly than the treatments tested. In the second part of this investigation, laboratory tests to determine semen quality were examined. It was hypothesised that semen quality would correlate with performance determined during the in vitro trial and, thus, provide predictors for bull fertility in vitro. A dual staining procedure which detects live/dead or acrosome reacted/not acrosome reacted sperm was also utilised to determine whether bull x treatment interactions may have existed in the in vitro trial but were obscured by other factors influencing the IVF system. Sperm motility and abnormal morphology were assessed using light microscopy on whole frozen-thawed semen samples. Statistical analysis could not be done because of lack of replication. Percentages of immotile sperm were high (60.16% to 78.51%), with considerable variation in progressive motility (13.90% to 34.35%) between bulls. A large variation in numbers of morphologically normal sperm was observed between bulls (66% to 90%), with major deformities (9% to 19%) accounting for most of the abnormalities. High negative correlations with performance (as defined in the in vitro trial) were found between % normal sperm and % proximal droplets (r=-0.66 to -0.88). Percentage of minor abnormalities, distal droplets and coiled tails correlated positively with fertility (r=0.67 to 0.91). Motility did not correlate highly with any of the criteria used to assess bull performance. Correlations of semen quality to performance were contradictory to expected results and this may have been due to swim-up separation of sperm for the in vitro trial which was not carried out for semen quality assessment. At present, these semen quality tests do not allow prediction of bull fertility in vitro. Assessment of sperm stained for evaluation of live/dead and acrosome reacted/not acrosome reacted was a lengthy procedure. Again, statistical analysis was not possible due to the lack of replication. High percentages of sperm were characterised as dead (52.4% to 100%). Bulls did respond differently to the various treatments, as determined by the proportion of acrosome reacted sperm and live acrosome reacted sperm. Thus, bull x treatment interactions were apparent, suggesting that the IVF system was more strongly influenced by other factor(s) which reduced sensitivity to the treatments tested. In summary, more research is needed to stabilise the IVF system if production of large numbers of embryos is to become economically viable.
The effect of stocking rate on the performance of beef cows and their progeny in the highland sourveld areas of Natal.
(1988) Van Niekerk, Alvin.; Lishman, Arthur William.
In three separate. but related studies, the performance of weaner/replacement heifers, dry pregnant cows, and first calvers and mature cows and their progeny, at different stocking rates in the Highland Sourveld, was investigated. The study area was located in Bioclimatic region 4e in the Province of Natal, Republic of South Africa. In the first study, carried out over four seasons, the effect of winter and summer nutritional levels on the performance of replacement heifers, bred at two years of age, was investigated. The results of this study indicated that compensatory growth was a potentially important factor in reducing feed costs, but the degree of compensation was highly dependent upon stocking rate and the condition of the veld. The most economical regime for rearing heifers up to the mating stage was a low growth rate (0 - 0,25 kg/day) during the first winter (post weaning) followed by a low stocking rate (0,75 AU/ha) on summer veld. Treatment did not generally affect the number of heifers attaining puberty, nor their conception rates. Pregnancy rates as high as 96% were achieved. Treatment also had no apparent effect on subsequent calving rates. In the second series of experiments, the role of condition scoring as a management tool in the Highland Sourveld was studied. The condition score of the cow was shown to be an important factor determining conception rate and time of conception. Only 8% of the cows mated at a condition score of 1,5, conceived, whereas 80% conception rates were achieved when the cows were mated at a condition score of 3,0 - 3,5. The cost of improving a cow's condition from 1,5 to 3,0 was R108, whereas the cost of improving a cow's condition from 2,0 to 3,0 was R54. In the third study, carried out over nine consecutive seasons, the effect of stocking rate and lick supplementation on the performance of iactating cows and first calvers was investigated. Four stocking rates were applied - 0,83, 1,0, 1,25 and 1,67 cows plus calves per hectare. The very high stocking rate was terminated after four seasons because of a significant decline in both cow and calf performance, and the severe deterioration of the natural pasture. There was no benefit to either the cows or calves with access to a urea-based lick at the very high stocking rate, but at the low stocking rate (1,0 cow + calf/ha) the cows were in such a condition that the grazing season could have been extended, thereby saving on winter feed costs. First calvers produced weaners as heavy as those of the mature cows and were in similar body condition at the end of the grazing season. The excellent performance of the first calvers was attributed largely to the fact that they calved 3 - 4 weeks prior to the mature cows. The grazing behaviour of the first calvers and the mature cows, at the different stocking rates, was observed in the fourth study which was carried out over two consecutive seasons. There were no significant differences in the grazing time between the first calvers and the mature cows at any of the stocking rates. In all the treatments, the first calvers appeared to establish the grazing patterns, with the mature cows adopting a followership role. Alloparental behaviour was noted in the early part of both grazing seasons.
The importance of age at first calving, relationship between body mass and fertility and feeding systems on production in the beef female.
(1978) Meaker, Helgaard Johannes.; Lishman, Arthur William.
No abstract available.
Improving calving rates in Afrikaner cattle.
(1997) Lishman, Arthur William.; Gous, Robert Mervyn.
No abstract available.
The influence of energy density on the performance of feedlot cattle.
(2002) Dominy, Neil John.; Nsahlai, Ignatius Verla.; Lishman, Arthur William.
This study examined the interaction of diets differing in their energy densities and heat increments of feeding on the feed intake patterns, physiological measurements, empty body composition, and animal performance of steers in a feedlot environment. The energy densities of the diets ranged from 7.97 to 11.83 MJ ME and 6.50 to 9.53 MJ Effective Energy (BE) and the ratio of EE to ME ranged from 0.79 to 0.84. The feed intake pattern of steers was not affected by differences in the diets energy densities but was affected by diets that differed in their heat increments of feeding. The physiological measurements, rectal temperatures measured at 9.00 am and 2.00 pm (TR 9.00 am and 2.00 pm) and respiration rates of steers in the feedlot were compared to control steers kept on pasture. Steers in the feedlot registered significantly (P < 0.001) higher physiological measurements than the controls and the accepted norms for cattle not under heat stress. A relationship exists between the pattern of physiological measurements over time and feed intake pattens over time. Physiological measurements peak and dip during the same weeks as the feed intakes peak and fall. Peaks and the immediate dips thereafter are related to points of acute response resulting in a chronic response and acclimatisation. All feedlotted steers experienced heat stress within the first week of feeding. Steers feedlotted in summer took 28 days to achieve their peak feed intake whereas steers feedlotted in winter required 42 days to reach their peak feed intake. Steers that required 42 days in which to reach their peak intakes had greater increases in their daily intakes than those that required 28 days to reach their peak intakes. Steers feedlotted in winter lost their winter coat between weeks three and six. Differences in peak feed intakes were recorded for animals of a heavier starting live weight (late versus early maturing and long yearling versus weaners). Peak feed intake increased in line with increasing live weight at the start of feedlotting. These differences were attributed to their greater surface area and hence greater heat loss capacity. Comparison of steers tissue deposition rates of steers on diets differing in their ratio of EE to ME revealed non significant differences in the growth rates of protein and lipid. The proportional use of energy intake was significantly different with significantly (P < 0.1) more of the daily energy intake being utilised for lipid deposition in diets with a higher heat load. Animals suffering from differing heat loads were inhibited in depositing protein but were able to deposit lipid due to the associated lower heat production. This enforced deposition of lipid results in animals reaching slaughter condition after similar lengths of time but at lower ADG and lower carcass weights. The economic consequences are that the returns are higher due to higher carcass gains for steers fed diets with a higher ratio of EE to ME.
The influence of suckling during early lactation on the resumption of ovarian activity and oestrous behaviour in the Afrikaner cow.
(1986) Wells, Peter Lee.; Lishman, Arthur William.
No abstract available.
The influence of variations in the level of nutrition on reproduction in the ewe.
(1972) Lishman, Arthur William.; Stielau, Werner Johannes.
No abstract available.
Intensive beef production on cultivated pastures in a sub-tropical environment.
(1984) Louw, Brian Peringuey.; Lishman, Arthur William.
The comparative performance of spring-calving beef cowherds comprising either Dual Purpose (Simmentaler) or British-cross (Hereford x Africaner) cows and calves was investigated at stocking rates of 3,0, 4,12, 5,34 and 6,74 cows and calves/ha on Kikuyu pasture over three seasons. An increase in stocking rate was associated with a decrease in the length of the grazing period, an increase in the mass and condition loss of cows, a decrease in calf livemass gains, a decrease in milk production, an increase in the production of beef per hectare and a decrease in margins over feed costs per cow. Stocking rate did not influence reconception rates, which averaged 65% over the three seasons. Simmentaler cows produced calves approximately 2 kg heavier at birth and 24 kg heavier at weaning, approximately 1,4 litres of milk more per day, lost more condition and attained higher margins over feed costs per cow and per hectare than Hereford-cross cows. Season influenced the length of the grazing season, birth mass, livemass gains in calves and mass changes in cows. Milk production accounted for 40% of the variation in calf gains on pasture. The conversion of milk to calf gain was influenced by milk yield, stocking rate, breed and calf sex. Ovarian and endocrinological responses associated with normal and restricted suckling for a 15-day period at two postpartum stages (Days 35 to 50 and 60 to 75) were examined in Bos taurus and Bos indicus cows. All cows received progestagen therapy, followed by GnRh administration during the periods of variable suckling intensity. Restricted suckling exerted little influence in Bos taurus cows, but tended to improve the ovulatory response, to decrease the incidence of "short" cycles and to increase reconception rates in Bos indicus cows. Treatment exerted no influence on calf growth and on tonic LH and oestrogen secretion. Bos indicus cows suckled normally released more LH in response to GnRh than Bos taurus cows. Bos indicus cows suckled once daily secreted less LH in response to GnRh than those suckled normally. Seasonal effects on tonic LH, and progesterone secretion were studied in cycling Friesland cows. Mean tonic LH levels during autumn were significantly higher than those during summer and spring. Season. exerted no influence on progesterone secretion.
Luteal function during early post partum in the ewe.
(1984) Grobbelaar, Johan.; Lishman, Arthur William.
No abstract available.
Optimization, validation and application of radioimmunoassays for plant growth substances in avocado (Persea americana Mill.) fruits.
(1984) Cutting, Jonathan Garth Melville.; Wolstenholme, B. Nigel.; Lishman, Arthur William.
The objective was to develop, optimize and validate radioimmunoassays (RIA) for several plant growth substances (PGS) and then apply the RIA's to determine PGS trends in 'Fuerte' avocado fruits from fruit set to fruit ripening. Antibodies to the cytokinin isopentenyl adenosine (IPA) were obtained from rabbits inoculated with a periodate-derived IPA-BSA conjugate. The antiserum cross-reacted (25%) with only 2iP (isopentenyl adenine). The RIA measuring range was from 0,1 to 100 ng. Anti-IPA serum was used to develop a RIA for 2iP, with a measuring range from 0,5 to 100 ng. Using Dowex 50W-X8 and cellulose TLC purified avocado fruit extract, 20 samples per day could be processed. The RIA for abscisic acid (ABA) was developed from rabbit antibodies from an inoculated carbodiimide-derived, (+ -) ABA-BSA conjugate. The free active ABA component was isolated prior to quantitation by RIA by solvent partitioning and silica gel TLC. The indole-acetic-acid (IAA) RIA was established from sheep-produced antibodies to a formaldehye-derived IAA-BSA conjugate, after repeated inoculations. For both the ABA and IAA RIA's, contaminants in the avocado tissue were removed by solvent partitioning. Developing avocado fruits, and especially young fruits were rich sources of IAA and 2iP in particular with seed concentrations exceeding those of the fruit flesh. The concentration of ABA rose throughout fruit development, reaching 100 ng g(-1) in the flesh at fruit maturity. Just prior to seed and fruit maturity, relatively high levels of IAA, 2iP and IPA were associated with the thick, fleshy testa, rapidly declining to zero as the testa dried. The avocado fruit is physiologically dependent on the seed right up to this stage, and testa maturity correlates well with minimum "legal" maturity of 80% moisture content of flesh. In ripening avocado fruit, the concentration of free ABA rose as softening progressed. Total ABA concentrations fell initially, and then rose after a firmometer reading between 50 and 60 (100 coincides with eating ripeness). Later harvested fruit had double the ABA concentration of early harvested fruit. The ripening stimulus appeared to be related to moisture stress in the fruit. This study has confirmed the prime advantages of sensitivity, specificity and rapidity of RIA, as well as its usefulness in multi-PGS studies and batch-type analysis.
Some factors affecting weaning weights of calves.
(1996) Kunene, Nokuthula Winfred.; Lishman, Arthur William.
A mixed model study was carried out on the field data records of 9798 Simmmental and 1725 Hereford calves born during the period 1992 to 1994, and obtained from the Animal Improvement Institute, Irene. The records were used to evaluate the influence of type of management systems used by breeders, type of vegetation, sex of calf, age of dam, year of birth and season of birth on 205 day weight of calves and some two way interactions between these effects. The analysis were carried separately for each breed. Type of management did not significantly affect the 205 day weight of Hereford calves, the least-squares means of calves from extensive, semi-extensive and intensive systems were 195.8, 196.9 and 197 kg, respectively. However, the effect was highly significant (P<.01) for Simmmental calves with weaning weights of 217.4, 238.3 and 261.2 kg for extensive, semi-extensive and intensive production systems, respectively. The Simmmental data were divided for further analysis according to the three management systems. All the main effects on the 205 day weight of Simmmental calves were highly significant for all the management systems. Simmmental calves raised in the combination of fynbos and pastures under the semi-extensive management system weaned the heaviest calves (295.8 kg) and those raised in the mixed grassveld under the extensive system weaned the least (202.4 kg) . The Simmmental male calves were 10, 9.8 and 17.9 kg heavier than female calves in the extensive, semi-extensive and intensive systems respectively. The mature age of the dam was between the 52 to 57, 58 to 117 and 52 to 57 month age groups with weaning weights of 230.7, 257.7 and 266.4 kg in the extensive, semi-extensive and intensive systems respectively. The deviations of weight of calves of the mature dams from those of young dams (16 to 27 months) were 26.9, 30 and 20 kg under the extensive, semi-extensive and intensive systems, respectively. The main effects on the 205 day weight of Hereford calves, except the type of management, were highly significant (P<.01). The Hereford calves raised in the sweetveld areas produced the highest weights (218.6 kg) but those raised on the karroo were the lightest (188.1 kg). The best calving seasons were autumn and winter, with the mean weight of 215.1 kg and 202.9 kg, respectively. Summer and spring born calves weighed 180.2 and 188.2 kg, respectively. The Hereford male calves were 13.2 kg heavier than the heifers. The maturity age of the dams was between the 72 to 95 month age group with the deviation of 20 kg in weaning weight of their calves from those of the young dams (22 to 27 months old). The sex and age-of-dam interaction for both breeds indicated an overall correction factor for sex of calf and of age of dam. Multiple adjustment factors were used to remove sex of calf differences, whereas additive adjustment factors were used to remove age-of-dam differences.
Suckling behaviour and fertility in beef cows on pasture.
(1990) Stewart, Iona Boles.; Lishman, Arthur William.
The suckling behaviour of 66 Hereford and Simmentaler cows was studied. The average frequency of suckling in 24 hours was four times, and the average duration of each suckling bout was 10 minutes. Suckling events were not evenly distributed throughout the 24 hour period. Regardless of suckling frequency or days post partum, the most favoured suckling period was between 04:00 and 06:00, i.e. dawn. The lowest incidence of suckling was recorded in the period from midnight to dawn. The longest interval between two suckling bouts over the 24 hours always occurred before the dawn and became longer as the calf grew older (p<0,01). Once the mating season commenced, the onset of oestrus was positively correlated (p<0,01) to the length of the longest inter-suckling period. Suckling behaviour was not affected by the milk yields of the cows studied . In a follow up investigation, 88 cows were separated from their calves for 12 hours out of 24, for the fortnight prior to the start of the breeding season. Fifty-six percent of the 44 cows which were separated from their calves from 18:00 to 06:00 (dayfeeders) exhibited oestrus within 28 days of the breeding season, compared to 22% of the group separated from 06:00 to 18:00 (p<0,01). It was concluded that not only the suppression of suckling may be involved in the onset of ovarian activity . The specific time period during the 24 hours when suckling is prohibited may also play a role.
Testing the libido of breeding sires to predict mating performance in the field and the hormonal control of male sexual behaviour.
(1988) Crichton, James Spencer.; Lishman, Arthur William.
The incidence of sexually low-response rams was determined in a group of 31 young Ile de France stud rams by means of three libido tests. Eight rams ( 25,8%) we reclassified as being sexually low-response. The proportion of rams showing normal sexual behaviour did not increase over the three tests. As testing progressed the incidence of mounting behaviour increased significantly. The increase in serving activity was non-significant. Following flock mating two low-response rams had not marked any ewes and showed preference for homosexual company. Five of the eight low response rams had a common sire and it is suggested that sexual behaviour may be influenced genetically. A group of 20 month-old beef bulls (n=54) representing nine breeds were evaluated for libido using five serving capacity (SC) tests (bulls tested in groups) followed by one libido score test (bulls tested as individuals). Bos indicus bulls displayed significantly lower SC than bulls from exotic breeds. Bulls underwent a definite learning process over the five SC tests. The increase in SC was not significant for all breeds. The use of oestrous teaser females held no advantage over the use of properly restrained non-oestrous females. Agonistic behaviour did not depress SC (individual exceptions were noted). Growth rate did not have a consistent effect on SC. Activity on the libido score test was highly significantly correlated to SC. The influence of night or day and the presence or absence of an observer on the SC of 20 month-old Bos indicus bulls (n=18) was evaluated over 12 SC tests. Bulls showed no preference for nocturnal sexual behaviour and were not hindered by personnel scoring SC. The improvement in SC with progression of the tests suggested some form of adaption to pen test conditions and/or learning experience. Serving behaviour was however inconsistent from test to test indicating that restrained females do not represent the ideal stimulus. Agonistic interaction depressed SC. Subsequent pasture mating behaviour was significantly related to SC. Some of the factors influencing pasture behaviour are discussed. High SC bulls achieved a conception rate that was 10,8% higher than that of the low SC bulls (difference non-significant). The relationship between bull libido (libido score test) and conception rate following a 21 day breeding season was investigated over two seasons. The average bulling percentages were 2,9 and 2,5% in the first and second seasons respectively. High libido bulls had no advantage over medium libido bulls in both seasons. Bulls achieved acceptable conception rates (> 70%) in both years and it is suggested that the commonly recommended bulling percentage of 4% is conservative. In an investigation into the hormonal control of sexual behaviour in the ram the technique of active immunization against specific steroid hormones was used in an attempt to highlight the possible central action of dihydrotestosterone (DHT) on mounting behaviour. The central aromatization of testosterone gives rise to DHT and oestradiol (E2). Immunization against E2 and a combination of oestrone (E1) and E2 in testosterone propionate (TP) implanted wethers reduced mounting behaviour to animals (no exogenous hormone). levels seen in control Results suggest that DHT has no or limited central nervous action. The effect of DHT appears to be largely via its sensitization of the penis which enhances mounting behaviour in DHT+E2 implanted wethers to levels higher than those recorded in E2 implanted wethers but similar to the activity recorded for wethers receiving TP implants.