Francois Siebrits - Academia.edu (original) (raw)

Papers by Francois Siebrits

This study was conducted to determine the effects of increasing dietary polyunsaturated fatty ac-... more This study was conducted to determine the effects of increasing dietary polyunsaturated fatty ac-ids (PUFA) and antioxidants (Se and vitamin E) on spermatozoa morphology. At 24 weeks of age, Potchefstroom Koekoek cockerels (n = 60) were selected from the base population. Cockerels were randomly allocated into five dietary treatments with 12 cockerels per dietary treatment. The diets consisted of commercial layer diet (CL), commercial cockerel diet (CC), modified layer diet (ML), modified layer diet +PUFA (MLP), and modified layer +PUFA+ antioxidants (MLPA) diet. At 36 weeks of age, six cockerels with ≥ 75 % sperm motility rate following analysis by Computer Aided Sperm Analysis (CASA) were selected from the base population in each dietary treatment group. Semen volume, sperm cells concentration and dead cells did not differ significantly among any of the groups. However, live and normal spermatozoa were significantly higher in the MLPA group. The bent mid-piece, bent mid-piece plus ...

Journal of Advanced Agricultural Technologies

The aim of the study was to investigate the effect of dietary fish oil supplementation on the sem... more The aim of the study was to investigate the effect of dietary fish oil supplementation on the semen characteristics of the Potchefstroom Koekoek cockerels. Thirty cockerels were divided into five groups, kept in individual cages and received five different diets: Commercial layer diet (CL), commercial cockerel diet (CC), modified layer diet (ML), modified layer diet supplemented with 5% fish oil (MLP) and a modified layer diet supplemented with 5% fish oil, 200mg/kg vitamin E and 5mg/kg selenium. Semen was collected twice a week on Mondays and Fridays. Semen characteristics were evaluated. Supplementation of fish oil did not significantly improve semen volume and sperm concentration. However, supplementation with polyunsaturated fatty acids and antioxidants increased the percentage of live and normal, as well as total motility of spermatozoa. The percentage of spermatozoa with mid-piece abnormalities and static motility were reduced in cockerels fed the MLPA diet. The supplementation of polyunsaturated fatty acids and antioxidants was associated with improved semen characteristics. Similarly, the supplementation of antioxidants provided enhanced protection against midpiece abnormalities 

Animal Production, 1990

Seventy-two Landrace pigs were used to study the effects of dietary crude protein concentration (... more Seventy-two Landrace pigs were used to study the effects of dietary crude protein concentration (197, 168 and 137 g/kg air dry meal), sex, type and live weight on the whole- body (gut content included) amino acid composition of growing pigs. Boars and gilts from two types (lean and obese) slaughtered at 20, 30 or 90 kg live weight were used. Mean whole-body amino acid concentrations were: lysine 63·4; methionine 21·8; cystine 15·8; threonine 35·1; leucine 67·7; isoleucine 28·0; valine 40·5; phenylalanine 35·5; tyrosine 24·6 and histidine 26·8 g/kg protein. Dietary protein concentration had no effect on body amino acid composition. Boar values tended to be higher than those of gilts but there were no significant differences. Pigs of the obese type also tended to have higher values than lean pigs, with significant differences obtained for methionine, cystine, leucine, and isoleucine. Apart from cystine, live weight had no effect on whole-body amino acid composition, Cystine content ho...

Book of abstracts: e-ISBN: 978-90-8686-578-9; p116

The determination of feedstuff quality can improve formulation strategies aimed at increasing pro... more The determination of feedstuff quality can improve formulation strategies aimed at increasing production from ruminant livestock. Organic matter digestibility (OMD) determination is routinely done using an in vitro method, with Tilley and Terry (1963) as the benchmark. Many adaptations have been made to this and its use is restricted by availability of surgically altered livestock from which ruminal fluid can be extracted. The development of an alternative method is indicated to take away the need for donor animals. A pepsin-acid multi enzymatic in vitro (PME) method which does not use ruminal fluid, a modified Tilley and Terry two stage in vitro (MT) method and a standard in vivo were used to test 17 feedstuffs, ranging from grasses to grains, samples for OMD. No differences for the mean of the treatments (760, 769 and 759 g OM/kg DM for in vivo, MT and the PME method respectively) were observed. Regression analysis was used to determine equations to relate the results of MT and PM...

Processes of preparing balanced diets, limitations in the supply of suitable feedstuffs to captiv... more Processes of preparing balanced diets, limitations in the supply of suitable feedstuffs to captive animals and their diversity in the zoological community are special challenges to diet management. The knowledge of the nutrients needed by the animal and what feeds will supply those nutrients, is one of the most important steps in managing diet of animals in captivity. In the Nationa Zoological Gardens of South africa, the food items were mainly composed of plants, vegetables, meat, fish, invertebrate and vertebrates, pellets, forages and some supplement. Literature survey and laboratory analyses were used to determine their nutrients composition. International Network of Feed Information Centres (INFIC) nomenclature was adopted to describe the dietary items. Results revealed that feeding practices in zoological gardens are based on common nutritional knownledge, human understanding and livestock nutrition. There were significant nutritional differences between lucerne in winter and ...

South African Journal Of Animal Science

The value of cold press soya bean oil cake (CPSBOC) as the source of protein in beef cattle was e... more The value of cold press soya bean oil cake (CPSBOC) as the source of protein in beef cattle was evaluated. CPSBOC was included in the diets of beef weaners at different levels i.e. 0%, 6%, 13% and 20%. The control diet contained cotton seed oil cake (CSOC) as a protein source. The diets were formulated to be isonitrogenous. A total of 40 weaners (20 heifers and 20 steers) at an average weight of 192.3 ± 20 kg were used. The experiment was a randomized block design with ten replicates per treatment and was conducted over 98 days. The group mass of the steers (700 ± 7.80 kg) was significantly heavier when compared with the heifers (6480 ± 7.80 kg). The average daily gain (ADG) (1.5 ± 2.72) and feed conversion ratio (FCR) (5.5 ± 0.051) of the steers was significantly better than the heifers (1.35 ± 2.72 and 5.7 ± 0.051, respectively) while the steers consume more feed (8.2 ± 14.4 kg) per day as compared to the 7.4 ± 14.4 kg consumed by heifers. The weaners that were fed the diet contai...

South African Journal Of Animal Science

There is concern whether cabbage and beetroot wastes from the Fresh Produce Market are safe for f... more There is concern whether cabbage and beetroot wastes from the Fresh Produce Market are safe for feeding animals given the fact that some will have been discarded at the onset of putrefaction. This study evaluated the effects of sun-drying on microbiological load (E. coli, coliform, yeast and moulds and total bacterial count) in waste vegetables from the fresh produce market, since smallholder farmers tend to use the by-products without processing given the opportunity. Cabbage and beetroot wastes were sun dried to 14% moisture and micro-organisms were enumerated on both wet and dried samples. The results showed that sun drying reduced the level of micro-organisms significantly in both cabbage and beetroot. Although microbial load varied from batch to batch in the wet samples, coliforms were significantly more abundant in wet beetroot than in the dried samples. However, dried beetroot contained significantly more yeast and moulds. Wet cabbage contained more coliform and yeast and mou...

Open Journal of Animal Sciences, 2015

This study was conducted to determine the effects of increasing dietary polyunsaturated fatty aci... more This study was conducted to determine the effects of increasing dietary polyunsaturated fatty acids (PUFA) and antioxidants (Se and vitamin E) on spermatozoa morphology. At 24 weeks of age, Potchefstroom Koekoek cockerels (n = 60) were selected from the base population. Cockerels were randomly allocated into five dietary treatments with 12 cockerels per dietary treatment. The diets consisted of commercial layer diet (CL), commercial cockerel diet (CC), modified layer diet (ML), modified layer diet +PUFA (MLP), and modified layer +PUFA+ antioxidants (MLPA) diet. At 36 weeks of age, six cockerels with ≥ 75% sperm motility rate following analysis by Computer Aided Sperm Analysis (CASA) were selected from the base population in each dietary treatment group. Semen volume, sperm cells concentration and dead cells did not differ significantly among any of the groups. However, live and normal spermatozoa were significantly higher in the MLPA group. The bent mid-piece, bent mid-piece plus droplets, proximal droplets and distal droplets were significantly lower in the MLPA group. From this study it can be concluded that supplementation of polyunsaturated fatty acids and antioxidants may be of vital importance for normal morphology characteristics of spermatozoa in Potchefstroom Koekoek cockerels.

Comparative biochemistry and physiology. A, Comparative physiology, 1989

1. Protein synthesis, net deposition and breakdown was studied in the gastrocnemius muscles of gr... more 1. Protein synthesis, net deposition and breakdown was studied in the gastrocnemius muscles of growing rats between weaning and 90 days of age. 2. Fractional protein synthetic rates declined from 30.02% at 25 days to 7.41% at 90 days. 3. The rate of protein degradation follows a similar pattern to that of protein synthesis. A linear relationship was found. 4. The break in the growth curve between 30 and 31 days was also observed in protein metabolism.

Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie, 2012

The current regression equations for the prediction of pig carcass lean content in South Africa w... more The current regression equations for the prediction of pig carcass lean content in South Africa were calculated in 1992 and had not been updated since, whilst pig carcasses became much leaner and often heavier than the 90 kg originally used. It therefore became necessary to critically evaluate the classification regressions to establish whether the genetic improvement had a substantial effect on lean prediction and whether the same regression may be extrapolated to heavier carcasses. Ultimately, it must be established whether the producer is fairly remunerated. Eighty-one pigs, consisting of five representative genotypes and three sexes (gilts, boars and barrows) at a live mass between 20 kg and 30 kg, were allocated to eight slaughter groups, fed a standard diet ad libitum and slaughtered at live masses ranging from 74 kg to 160 kg. Fat measurements were taken on the carcasses using a Hennessy Grading Probe® and an Intrascope®, whereafter the left sides were divided into wholesale ...

International Journal of Biochemistry, 1985

1. Protein synthesis in muscle and liver were studied in rats in early and peak lactation. 2. Whi... more 1. Protein synthesis in muscle and liver were studied in rats in early and peak lactation. 2. While the fractional synthetic rate of liver was greatly enhanced there were no significant changes in muscle. 3. No evidence was obtained for a marked contribution of muscle protein for the demand of lactation.

South African Journal of Animal Science, 2014

Point-of-care (POC) devices were used to measure plasma metabolic substrates in pigs subjected to... more Point-of-care (POC) devices were used to measure plasma metabolic substrates in pigs subjected to stressful conditions. These were then related to the meat pH, drip loss and carcass temperature. Forty Large White x Landrace pigs (20 females and 20 males) weighing approximately 67 ± 6.5 kg were used in the study. Twenty of the pigs were subjected to a stressful regimen for two hours and the other 20 pigs were transported for 15 minutes from their pens directly to the abattoir. Salivary cortisol, plasma glucose, triglycerides and lactate concentrations were determined before and after transportation to the abattoir and carcass temperature, pH and drip loss were measured after slaughter. There were no differences in the lactate, cortisol, pH and triglycerides measurements from the pigs of different sexes. Female pigs had higher carcass temperature and lower glucose levels than male pigs. Regression analysis showed that back fat and lactate accounted for 99% of variation in the pH 24h of pigs transported over a short duration while lactate was responsible for only 16% of the variation in pigs transported over the long duration. The difference in lactate accounted for 78% of variation in the carcass temperature at 45 minutes for pigs transported over the short duration while in the long duration group, the weight was responsible for 81% of the variation. In conclusion, POC devices measured differences in lactate concentrations in pigs transported over different durations and relationships between the lactate and the carcass pH, carcass temperature and drip loss was determined.

South African Journal of Animal Science, 2000

The aim of the study was to determine the optimum protein inclusion level in diets containing an ... more The aim of the study was to determine the optimum protein inclusion level in diets containing an ideal amino acid balance for growing pigs. The performance of commercial crossbred grower-pigs was studied in two trials in which the experimental animals were housed either in commercial-type group housing (experiment1) or in individual pens (experiment 2). Treatments consisted of diets containing 14%, 16%, 18% or 20% crude protein. Lysine, tryptophan, threonine and total sulphur-containing amino acids were included in all diets at levels equivalent to that supplied by the 18% crude protein diet. In experiment one, 144 pigs (72 boars and 72 gilts) of initial mass 30 kg were fed until slaughter at 70 kg. In experiment two, 80 pigs (40 boars and 40 gilts) of live masses ranging from 17.5 to 31.1 kg were fed until slaughter at masses between 64 and 105.5 kg. There were no differences between treatments (p > 0,05) for daily gain, feed conversion ratio, daily intake or carcass classification, but feed conversion ratio differed between sexes in experiment two (p < 0.05). It was concluded that protein inclusion levels in pig growth diets could be decreased from 18% to 14% without any detrimental effect on performance, provided that the digestible essential amino acid composition is adjusted to meet requirements. This practice is however not economically viable for South African pig producers at the prevailing price of synthetic amino acids.

South African Journal of Animal Science, 2000

Three in vivo techniques were evaluated in terms of their suitability for determination of the ap... more Three in vivo techniques were evaluated in terms of their suitability for determination of the apparent ileal amino acid digestibility (AID) of protein sources for piglets. The techniques were: ileo-rectal anastomosis (IRA), cannulation at the distal ileum and a slaughter technique. A standard diet and three diets in which 20% of the standard diet was substituted with either skim milk powder (SMP), fish meal or roasted full-fat soya beans (FFS) were used. Piglets were weaned at 21 days of age, and the respective diets were fed in 24 equal hourly portions per day from days 29-37. Ileal digesta was collected from day 33-37 in IRA and cannulated piglets. Piglets used for the slaughter technique were killed at 37 days of age and ileal digesta was collected. Chromium III oxide was used as an indigestible marker with all three techniques. Although AID means did not differ (p > 0.05) between the different techniques, the cannulation technique resulted in the lowest variation (standard error of the mean) of all treatments (8.2 vs 13.7 and 14.1 for the slaughter and IRA-techniques respectively). AID means obtained using the cannula technique were 1.8 percentage units higher for the SMP diet than values obtained using the other techniques (83.2 versus 81.4 %), and up to 9.3 percentage units higher for the FFS diet (75.4 versus 66.1 %). Growth data suggested that the cannulation technique caused less trauma for the piglets than the IRA-technique. IRA-piglets had not yet regained their initial weaning weight by 37 days of age, while the other piglets gained weight over the trial period. The cannulation technique is the most attractive method for use with piglets in terms of the lower variation in digestibility values. Practical aspects such as ease of handling and sampling, surgical trauma and piglet stress, are also important and contribute to the selection of the cannula technique as the most appropriate.

South African Journal of Animal Science, 2010

Lactate utilising bacteria (LUB) assist in reducing the risk of ruminal lactate acidosis when hig... more Lactate utilising bacteria (LUB) assist in reducing the risk of ruminal lactate acidosis when high concentrate diets are fed to feedlot cattle. Ruminal lactate acidosis can lead to lower animal performance and morbidity. Preliminary studies suggested that the strain, Megasphaera elsdenii (M.e.) NCIMB 41125, is a particularly potent LUB. The potential of M.e.NCIMB 41125 to improve the health and performance of feedlot cattle was investigated. Four hundred and forty eight Bonsmara steers (ca. 240 kg) were used in a 100-day feeding trial. Half the steers received at processing 200 mL M.e.NCIMB 41125 per os (LY) and the other half no LUB (LN). The diets in each of these treatments were divided into a low roughage (2%) (RL) and high roughage (8%) (RH) diet. The effects of LY vs. LN, RL vs. RH as main effects and their respective interactions (LYRL, LYRH, LNRL & LNRH) were compared in terms of morbidity, feedlot performance and carcass characteristics. The steers were weighed at two week intervals, feed was offered daily and the orts were removed weekly from each pen. The faecal consistency score and incidence of morbidity were recorded. At slaughter, carcass data were collected and the health status of the liver and rumen epithelium was assessed. Steers dosed with M.e.NCIMB 41125 had a 5.6% better average daily gain (ADG) during weeks 3-5 (2.09 kg/day vs. 1.98 kg/day for LY and LN, respectively). Feed conversion ratio (FCR, Weeks 1-13) was better for the steers fed the RL than the RH treatment (4.72 kg/kg vs. 4.99 kg/kg for RL and RH, respectively). Steers on the LNRH treatment during weeks 3-5 used more feed per kg gain than steers on the other treatments (5.39 kg/kg for LNRH vs. 4.74 kg/kg and 4.72 kg/kg for LYRL and LNRL, respectively). More steers (21) on the LNRL treatment were treated for morbidity than on the other treatments (8, 7 and 5 for LYRL, LYRH and LNRH, respectively). In general, animal performance was not improved by dosing with M.e.NCIMB 41125, but since ADG was improved in the immediate postadaptation phase (weeks 3-5) and morbidity levels were lower on the low roughage diet, dosing of steers on low roughage, lactate acidosis-prone, diets with M.e.NCIMB 41125 should prove useful.

This study was conducted to determine the effects of increasing dietary polyunsaturated fatty ac-... more This study was conducted to determine the effects of increasing dietary polyunsaturated fatty ac-ids (PUFA) and antioxidants (Se and vitamin E) on spermatozoa morphology. At 24 weeks of age, Potchefstroom Koekoek cockerels (n = 60) were selected from the base population. Cockerels were randomly allocated into five dietary treatments with 12 cockerels per dietary treatment. The diets consisted of commercial layer diet (CL), commercial cockerel diet (CC), modified layer diet (ML), modified layer diet +PUFA (MLP), and modified layer +PUFA+ antioxidants (MLPA) diet. At 36 weeks of age, six cockerels with ≥ 75 % sperm motility rate following analysis by Computer Aided Sperm Analysis (CASA) were selected from the base population in each dietary treatment group. Semen volume, sperm cells concentration and dead cells did not differ significantly among any of the groups. However, live and normal spermatozoa were significantly higher in the MLPA group. The bent mid-piece, bent mid-piece plus ...

Journal of Advanced Agricultural Technologies

The aim of the study was to investigate the effect of dietary fish oil supplementation on the sem... more The aim of the study was to investigate the effect of dietary fish oil supplementation on the semen characteristics of the Potchefstroom Koekoek cockerels. Thirty cockerels were divided into five groups, kept in individual cages and received five different diets: Commercial layer diet (CL), commercial cockerel diet (CC), modified layer diet (ML), modified layer diet supplemented with 5% fish oil (MLP) and a modified layer diet supplemented with 5% fish oil, 200mg/kg vitamin E and 5mg/kg selenium. Semen was collected twice a week on Mondays and Fridays. Semen characteristics were evaluated. Supplementation of fish oil did not significantly improve semen volume and sperm concentration. However, supplementation with polyunsaturated fatty acids and antioxidants increased the percentage of live and normal, as well as total motility of spermatozoa. The percentage of spermatozoa with mid-piece abnormalities and static motility were reduced in cockerels fed the MLPA diet. The supplementation of polyunsaturated fatty acids and antioxidants was associated with improved semen characteristics. Similarly, the supplementation of antioxidants provided enhanced protection against midpiece abnormalities 

Animal Production, 1990

Seventy-two Landrace pigs were used to study the effects of dietary crude protein concentration (... more Seventy-two Landrace pigs were used to study the effects of dietary crude protein concentration (197, 168 and 137 g/kg air dry meal), sex, type and live weight on the whole- body (gut content included) amino acid composition of growing pigs. Boars and gilts from two types (lean and obese) slaughtered at 20, 30 or 90 kg live weight were used. Mean whole-body amino acid concentrations were: lysine 63·4; methionine 21·8; cystine 15·8; threonine 35·1; leucine 67·7; isoleucine 28·0; valine 40·5; phenylalanine 35·5; tyrosine 24·6 and histidine 26·8 g/kg protein. Dietary protein concentration had no effect on body amino acid composition. Boar values tended to be higher than those of gilts but there were no significant differences. Pigs of the obese type also tended to have higher values than lean pigs, with significant differences obtained for methionine, cystine, leucine, and isoleucine. Apart from cystine, live weight had no effect on whole-body amino acid composition, Cystine content ho...

Book of abstracts: e-ISBN: 978-90-8686-578-9; p116

The determination of feedstuff quality can improve formulation strategies aimed at increasing pro... more The determination of feedstuff quality can improve formulation strategies aimed at increasing production from ruminant livestock. Organic matter digestibility (OMD) determination is routinely done using an in vitro method, with Tilley and Terry (1963) as the benchmark. Many adaptations have been made to this and its use is restricted by availability of surgically altered livestock from which ruminal fluid can be extracted. The development of an alternative method is indicated to take away the need for donor animals. A pepsin-acid multi enzymatic in vitro (PME) method which does not use ruminal fluid, a modified Tilley and Terry two stage in vitro (MT) method and a standard in vivo were used to test 17 feedstuffs, ranging from grasses to grains, samples for OMD. No differences for the mean of the treatments (760, 769 and 759 g OM/kg DM for in vivo, MT and the PME method respectively) were observed. Regression analysis was used to determine equations to relate the results of MT and PM...

Processes of preparing balanced diets, limitations in the supply of suitable feedstuffs to captiv... more Processes of preparing balanced diets, limitations in the supply of suitable feedstuffs to captive animals and their diversity in the zoological community are special challenges to diet management. The knowledge of the nutrients needed by the animal and what feeds will supply those nutrients, is one of the most important steps in managing diet of animals in captivity. In the Nationa Zoological Gardens of South africa, the food items were mainly composed of plants, vegetables, meat, fish, invertebrate and vertebrates, pellets, forages and some supplement. Literature survey and laboratory analyses were used to determine their nutrients composition. International Network of Feed Information Centres (INFIC) nomenclature was adopted to describe the dietary items. Results revealed that feeding practices in zoological gardens are based on common nutritional knownledge, human understanding and livestock nutrition. There were significant nutritional differences between lucerne in winter and ...

South African Journal Of Animal Science

The value of cold press soya bean oil cake (CPSBOC) as the source of protein in beef cattle was e... more The value of cold press soya bean oil cake (CPSBOC) as the source of protein in beef cattle was evaluated. CPSBOC was included in the diets of beef weaners at different levels i.e. 0%, 6%, 13% and 20%. The control diet contained cotton seed oil cake (CSOC) as a protein source. The diets were formulated to be isonitrogenous. A total of 40 weaners (20 heifers and 20 steers) at an average weight of 192.3 ± 20 kg were used. The experiment was a randomized block design with ten replicates per treatment and was conducted over 98 days. The group mass of the steers (700 ± 7.80 kg) was significantly heavier when compared with the heifers (6480 ± 7.80 kg). The average daily gain (ADG) (1.5 ± 2.72) and feed conversion ratio (FCR) (5.5 ± 0.051) of the steers was significantly better than the heifers (1.35 ± 2.72 and 5.7 ± 0.051, respectively) while the steers consume more feed (8.2 ± 14.4 kg) per day as compared to the 7.4 ± 14.4 kg consumed by heifers. The weaners that were fed the diet contai...

South African Journal Of Animal Science

There is concern whether cabbage and beetroot wastes from the Fresh Produce Market are safe for f... more There is concern whether cabbage and beetroot wastes from the Fresh Produce Market are safe for feeding animals given the fact that some will have been discarded at the onset of putrefaction. This study evaluated the effects of sun-drying on microbiological load (E. coli, coliform, yeast and moulds and total bacterial count) in waste vegetables from the fresh produce market, since smallholder farmers tend to use the by-products without processing given the opportunity. Cabbage and beetroot wastes were sun dried to 14% moisture and micro-organisms were enumerated on both wet and dried samples. The results showed that sun drying reduced the level of micro-organisms significantly in both cabbage and beetroot. Although microbial load varied from batch to batch in the wet samples, coliforms were significantly more abundant in wet beetroot than in the dried samples. However, dried beetroot contained significantly more yeast and moulds. Wet cabbage contained more coliform and yeast and mou...

Open Journal of Animal Sciences, 2015

This study was conducted to determine the effects of increasing dietary polyunsaturated fatty aci... more This study was conducted to determine the effects of increasing dietary polyunsaturated fatty acids (PUFA) and antioxidants (Se and vitamin E) on spermatozoa morphology. At 24 weeks of age, Potchefstroom Koekoek cockerels (n = 60) were selected from the base population. Cockerels were randomly allocated into five dietary treatments with 12 cockerels per dietary treatment. The diets consisted of commercial layer diet (CL), commercial cockerel diet (CC), modified layer diet (ML), modified layer diet +PUFA (MLP), and modified layer +PUFA+ antioxidants (MLPA) diet. At 36 weeks of age, six cockerels with ≥ 75% sperm motility rate following analysis by Computer Aided Sperm Analysis (CASA) were selected from the base population in each dietary treatment group. Semen volume, sperm cells concentration and dead cells did not differ significantly among any of the groups. However, live and normal spermatozoa were significantly higher in the MLPA group. The bent mid-piece, bent mid-piece plus droplets, proximal droplets and distal droplets were significantly lower in the MLPA group. From this study it can be concluded that supplementation of polyunsaturated fatty acids and antioxidants may be of vital importance for normal morphology characteristics of spermatozoa in Potchefstroom Koekoek cockerels.

Comparative biochemistry and physiology. A, Comparative physiology, 1989

1. Protein synthesis, net deposition and breakdown was studied in the gastrocnemius muscles of gr... more 1. Protein synthesis, net deposition and breakdown was studied in the gastrocnemius muscles of growing rats between weaning and 90 days of age. 2. Fractional protein synthetic rates declined from 30.02% at 25 days to 7.41% at 90 days. 3. The rate of protein degradation follows a similar pattern to that of protein synthesis. A linear relationship was found. 4. The break in the growth curve between 30 and 31 days was also observed in protein metabolism.

Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie, 2012

The current regression equations for the prediction of pig carcass lean content in South Africa w... more The current regression equations for the prediction of pig carcass lean content in South Africa were calculated in 1992 and had not been updated since, whilst pig carcasses became much leaner and often heavier than the 90 kg originally used. It therefore became necessary to critically evaluate the classification regressions to establish whether the genetic improvement had a substantial effect on lean prediction and whether the same regression may be extrapolated to heavier carcasses. Ultimately, it must be established whether the producer is fairly remunerated. Eighty-one pigs, consisting of five representative genotypes and three sexes (gilts, boars and barrows) at a live mass between 20 kg and 30 kg, were allocated to eight slaughter groups, fed a standard diet ad libitum and slaughtered at live masses ranging from 74 kg to 160 kg. Fat measurements were taken on the carcasses using a Hennessy Grading Probe® and an Intrascope®, whereafter the left sides were divided into wholesale ...

International Journal of Biochemistry, 1985

1. Protein synthesis in muscle and liver were studied in rats in early and peak lactation. 2. Whi... more 1. Protein synthesis in muscle and liver were studied in rats in early and peak lactation. 2. While the fractional synthetic rate of liver was greatly enhanced there were no significant changes in muscle. 3. No evidence was obtained for a marked contribution of muscle protein for the demand of lactation.

South African Journal of Animal Science, 2014

Point-of-care (POC) devices were used to measure plasma metabolic substrates in pigs subjected to... more Point-of-care (POC) devices were used to measure plasma metabolic substrates in pigs subjected to stressful conditions. These were then related to the meat pH, drip loss and carcass temperature. Forty Large White x Landrace pigs (20 females and 20 males) weighing approximately 67 ± 6.5 kg were used in the study. Twenty of the pigs were subjected to a stressful regimen for two hours and the other 20 pigs were transported for 15 minutes from their pens directly to the abattoir. Salivary cortisol, plasma glucose, triglycerides and lactate concentrations were determined before and after transportation to the abattoir and carcass temperature, pH and drip loss were measured after slaughter. There were no differences in the lactate, cortisol, pH and triglycerides measurements from the pigs of different sexes. Female pigs had higher carcass temperature and lower glucose levels than male pigs. Regression analysis showed that back fat and lactate accounted for 99% of variation in the pH 24h of pigs transported over a short duration while lactate was responsible for only 16% of the variation in pigs transported over the long duration. The difference in lactate accounted for 78% of variation in the carcass temperature at 45 minutes for pigs transported over the short duration while in the long duration group, the weight was responsible for 81% of the variation. In conclusion, POC devices measured differences in lactate concentrations in pigs transported over different durations and relationships between the lactate and the carcass pH, carcass temperature and drip loss was determined.

South African Journal of Animal Science, 2000

The aim of the study was to determine the optimum protein inclusion level in diets containing an ... more The aim of the study was to determine the optimum protein inclusion level in diets containing an ideal amino acid balance for growing pigs. The performance of commercial crossbred grower-pigs was studied in two trials in which the experimental animals were housed either in commercial-type group housing (experiment1) or in individual pens (experiment 2). Treatments consisted of diets containing 14%, 16%, 18% or 20% crude protein. Lysine, tryptophan, threonine and total sulphur-containing amino acids were included in all diets at levels equivalent to that supplied by the 18% crude protein diet. In experiment one, 144 pigs (72 boars and 72 gilts) of initial mass 30 kg were fed until slaughter at 70 kg. In experiment two, 80 pigs (40 boars and 40 gilts) of live masses ranging from 17.5 to 31.1 kg were fed until slaughter at masses between 64 and 105.5 kg. There were no differences between treatments (p > 0,05) for daily gain, feed conversion ratio, daily intake or carcass classification, but feed conversion ratio differed between sexes in experiment two (p < 0.05). It was concluded that protein inclusion levels in pig growth diets could be decreased from 18% to 14% without any detrimental effect on performance, provided that the digestible essential amino acid composition is adjusted to meet requirements. This practice is however not economically viable for South African pig producers at the prevailing price of synthetic amino acids.

South African Journal of Animal Science, 2000

Three in vivo techniques were evaluated in terms of their suitability for determination of the ap... more Three in vivo techniques were evaluated in terms of their suitability for determination of the apparent ileal amino acid digestibility (AID) of protein sources for piglets. The techniques were: ileo-rectal anastomosis (IRA), cannulation at the distal ileum and a slaughter technique. A standard diet and three diets in which 20% of the standard diet was substituted with either skim milk powder (SMP), fish meal or roasted full-fat soya beans (FFS) were used. Piglets were weaned at 21 days of age, and the respective diets were fed in 24 equal hourly portions per day from days 29-37. Ileal digesta was collected from day 33-37 in IRA and cannulated piglets. Piglets used for the slaughter technique were killed at 37 days of age and ileal digesta was collected. Chromium III oxide was used as an indigestible marker with all three techniques. Although AID means did not differ (p > 0.05) between the different techniques, the cannulation technique resulted in the lowest variation (standard error of the mean) of all treatments (8.2 vs 13.7 and 14.1 for the slaughter and IRA-techniques respectively). AID means obtained using the cannula technique were 1.8 percentage units higher for the SMP diet than values obtained using the other techniques (83.2 versus 81.4 %), and up to 9.3 percentage units higher for the FFS diet (75.4 versus 66.1 %). Growth data suggested that the cannulation technique caused less trauma for the piglets than the IRA-technique. IRA-piglets had not yet regained their initial weaning weight by 37 days of age, while the other piglets gained weight over the trial period. The cannulation technique is the most attractive method for use with piglets in terms of the lower variation in digestibility values. Practical aspects such as ease of handling and sampling, surgical trauma and piglet stress, are also important and contribute to the selection of the cannula technique as the most appropriate.

South African Journal of Animal Science, 2010

Lactate utilising bacteria (LUB) assist in reducing the risk of ruminal lactate acidosis when hig... more Lactate utilising bacteria (LUB) assist in reducing the risk of ruminal lactate acidosis when high concentrate diets are fed to feedlot cattle. Ruminal lactate acidosis can lead to lower animal performance and morbidity. Preliminary studies suggested that the strain, Megasphaera elsdenii (M.e.) NCIMB 41125, is a particularly potent LUB. The potential of M.e.NCIMB 41125 to improve the health and performance of feedlot cattle was investigated. Four hundred and forty eight Bonsmara steers (ca. 240 kg) were used in a 100-day feeding trial. Half the steers received at processing 200 mL M.e.NCIMB 41125 per os (LY) and the other half no LUB (LN). The diets in each of these treatments were divided into a low roughage (2%) (RL) and high roughage (8%) (RH) diet. The effects of LY vs. LN, RL vs. RH as main effects and their respective interactions (LYRL, LYRH, LNRL & LNRH) were compared in terms of morbidity, feedlot performance and carcass characteristics. The steers were weighed at two week intervals, feed was offered daily and the orts were removed weekly from each pen. The faecal consistency score and incidence of morbidity were recorded. At slaughter, carcass data were collected and the health status of the liver and rumen epithelium was assessed. Steers dosed with M.e.NCIMB 41125 had a 5.6% better average daily gain (ADG) during weeks 3-5 (2.09 kg/day vs. 1.98 kg/day for LY and LN, respectively). Feed conversion ratio (FCR, Weeks 1-13) was better for the steers fed the RL than the RH treatment (4.72 kg/kg vs. 4.99 kg/kg for RL and RH, respectively). Steers on the LNRH treatment during weeks 3-5 used more feed per kg gain than steers on the other treatments (5.39 kg/kg for LNRH vs. 4.74 kg/kg and 4.72 kg/kg for LYRL and LNRL, respectively). More steers (21) on the LNRL treatment were treated for morbidity than on the other treatments (8, 7 and 5 for LYRL, LYRH and LNRH, respectively). In general, animal performance was not improved by dosing with M.e.NCIMB 41125, but since ADG was improved in the immediate postadaptation phase (weeks 3-5) and morbidity levels were lower on the low roughage diet, dosing of steers on low roughage, lactate acidosis-prone, diets with M.e.NCIMB 41125 should prove useful.