Browsing by Author "Tyler, Nicola Claire."

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Bone quality and incidence of urolithiasis in male broiler breeders fed a male or female ration.
(2024) Dube, Sithembisiwe.; Tyler, Nicola Claire.
Separate sex feeding is highly practiced in breeder farms as it gives a more targeted approach to nutrition, aligning the dietary requirements with the specific needs of male and female birds. Some breeder farmers give the female ration to male breeders as it saves having two feed silos per house and eliminates the chances of females receiving the wrong feed. However, the drawback is that the female ration contains high crude protein (CP), calcium (Ca), and phosphorous (P), which is more than recommended for male requirements. A total of 40 male broiler breeders fed a male-specific ration (MM), and 40 male broiler breeders fed a female ration (MF) at depletion were acquired from KwaZulu-Natal farms. Kidney weight (KW) and kidney lesion score (KLS) from euthanised male broiler breeders were examined as an indication of urolithiasis. Tibia bone weight (BW), bone thickness(BT), bone breaking strength (BBS), tibia ash% (TA%), organic matter (OM%) and Ca/P% were quantified to assess the effects of excess CP, Ca and P on bone quality. Data collected were subjected to a two-sample t-test at a 95% confidence interval using GenStat statistical analysis software, and principal component analysis (PCA) was performed using XLSTAT. The biplots from the PCA were used to predict correlation among the variables. The study results showed that the kidney weights of MF were significantly larger compared to MM (P<0.001). Kidney lesion scores were observed in 50% MF and were significantly higher than in MM (P<0.001). Significant differences in BW, BBS, TA%, and OM% were found between MM and MF. Bone thickness, and bone Ca%, P% and Ca/P% were not significantly different among the two groups. The findings suggested that high CP, Ca and P in female feed given to male broiler breeders can negatively affect kidney and bone quality. The results indicated a significant correlation between dietary composition, bone strength and the incidence of urolithiasis. The study concluded that the nutritional composition designed for female broiler breeders may not be entirely suitable for the physiological needs of male breeders, contributing to an increased susceptibility to urolithiasis. Also, high Ca can interfere with the absorption or retention of Ca and other minerals like P, resulting in low bone quality.
Breast meat yield in broilers affected by lighting and dietary energy levels in starter and finisher phases.
(2015) Smith, Giles Elliott.; Ciacciariello, Mariana.; Tyler, Nicola Claire.
The increased demand in poultry products has prompted researchers to investigate opportunities and methods which may streamline the production of valuable commodities. Two experiments were conducted in this study. Both experiments were conducted to determine whether breast meat yield (BMY) would be enhanced in broilers reared under short daylengths of 8 and 16 h if higher levels of dietary metabolisable energy (ME) were fed. In each experiment, 1000 as hatched broilers were reared in four light tight rooms, each room divided into two pens which were populated with 125 chicks in each. Within each room two levels of dietary ME were fed resulting in a 2 × 2 factorial experimental design with the main effects being daylength and dietary ME. The first experiment focused on the starter phase of 1 to 10 d. The dietary treatments consisted of a control starter ration formulated to represent the nutrient levels of a standard commercial ration and a treatment ration which was similar to the control ration however contained 15% higher ME. Live weight and performance parameters of body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) were measured at 7 and 10 d. At 10d, three birds from each pen were randomly selected and slaughtered for body part analysis. Lighting and dietary treatment had no effect on live weight, BWG, FI and FCR at 7 or 10d. Body part analysis showed that BMY, thigh yield and drumstick yield were unaffected by lighting and dietary ME as main effects. A significant interaction between dietary ME and daylength occurred where BMY and thigh yield were reduced when broilers were fed a 15% higher ME diet and reared on 8 h daylengths. The second experiment focused on the finisher phase of 25 to 35d. Lighting treatments remained the same as the first experiment but dietary treatments differed slightly as the treatment diet contained only 10% higher ME than the control diet which was formulated to the nutrient levels of a standard broiler finisher. At 35 d performance parameters of live weight, BWG, FI and FCR were measured. It was observed that live weight and FI were reduced in broilers fed a diet containing 10% higher ME from 25 to 35d. At 35d, body part analysis from 3 broilers slaughtered from each pen revealed no significant differences in BMY, thigh yield and drumstick yield from dietary ME and daylength. Breast meat yield in broilers within the starter and finisher phase was not improved on short daylengths of 8 and 16 h through the addition of dietary ME in higher levels than that conventionally used.
Can small-scale poultry production contribute to household food security in the Maphephetheni lowlands, KwaZulu-Natal?
(2009) Mosisi, Moleka Pange.; Tyler, Nicola Claire.; Hendriks, Sheryl Lee.
This study investigated the feasibility of small-scale poultry production to contribute to household food security in the Maphephetheni lowlands in KwaZulu-Natal. Forty households, selected by stratified random sampling (eight households per sub-ward) participated in a trial to assess the feasibility of egg and broiler production, from commercial lines, and the potential for generating income to improve household food security. The study established that participating households acquired the necessary skills through a training module offered, actively engaged in poultry production and marketing of the produce, and managed their funds well. Market demand for poultry products in the Maphephetheni lowlands was high from both local consumers and traders. Egg production profit was constrained as eggs were not sorted into sizes according to South African standards and local selling prices, but, contrary to commercial market practice, the eggs are graded ‘standard’ regardless of size. Both egg and broiler production are technically feasible in Maphephetheni lowlands, but broiler production is more economically viable than eggs and more highly desired by households. Households reported that poultry production could provide much needed income and reduce poverty and hunger in their community. Although household dietary diversity did not improve, income increased and was put into a savings account. Households borrowed and used this money for various needs, but not necessarily to supplement their diets. Commercial point-of-lay pullets and three-week old vaccinated broilers could be used in the Maphephetheni lowlands, but broilers were more commercially viable than point-of-lay pullets. It is recommended that broiler houses be established with the capacity for brooding each 500 day-old chicks which are sold (live) at six weeks. However, technical and financial support is required to maximise the benefits, increase household income, improve diets and reduce vulnerability to food insecurity.
The effect of crude protein and calcium intake on fertility of male broiler breeders.
(2016) Namntu, Musawenkosi.; Tyler, Nicola Claire.
Broiler parent stock are selected to ensure that good characteristics will be passed to the offspring but management of broiler breeder birds is different to that of broiler chickens. Feeding broiler breeders ad libitum can result in body weight-related consequences such as musculo-skeletal disorders and the inability to mate successfully during natural mating. There is an age-related decline in fertility observed in broiler breeder flocks after 40 weeks of age. Management techniques such as feed restriction and spiking have therefore been employed to prolong and maintain fertility of breeders with increasing age. Feeding a female ration to male broiler breeders may negatively affect reproductive efficiency. The possibility that excess nutrients supplied to male broiler breeders influence fertility cannot be ignored because male fertility has a significant impact on overall flock fertility. Because the female broiler breeder has a higher requirement of protein and calcium, the effects of these on fertility of males fed a female ration are worth considering. The objective of this experiment was therefore to assess the effects of feeding four different diets, keeping feed allocation constant to result in 2 levels of crude protein intake and 2 levels of calcium intake (HP: LC, LP: HC, HP: HC, LP: LC) on semen quality of male broiler breeders in the production phase. An increase in crude protein intake significantly increased (p<0.05) body weight of male broiler breeders after 41 weeks of age with birds fed HP: LC, LP: HC and LP: LC being significantly different to males fed HP: HC. There was a significant CP x Ca intake interaction on male broiler breeder bodyweight after 52 WOA. There was no significant effect of CP intake on sperm concentration and sperm mobility. Calcium intake significantly decreased sperm concentration at 42 and 60 WOA but had no effect on sperm mobility. There was no significant influence of CP intake on sperm concentration with age. There was no significant response in overall log number of inner perivitelline layer sperm holes and across all ages. Log number of IPVL sperm holes declined with age from 37-59 WOA with day 2 post artificial insemination having a higher number of IPVL sperm holes counted across all ages.
The effect of crude protein intake on fertility in young and old male broiler breeders.
(2014) Graaf, Brendan.; Tyler, Nicola Claire.; Ciacciariello, Mariana.
Due to genetic selection and improvements in broiler growth traits there have been negative influences on fertility in broiler breeder parents. This is mainly related to excess body weight gain resulting in the inability to achieve successful cloacal contact during copulation and problems with the hierarchical formation of follicles in the ovary. Male broiler breeders are often fed a female ration which contains crude protein (CP) requirements for egg production, and may not be necessary for males. Protein is one of the most costly components of poultry feed, and overfeeding protein has a number of downsides. The impact of sub-fertile and unfertile males in the overall fertility of the flock could be large. Maximizing male fertility could ensure maximizing fertile egg production which would result in more broiler chicks without increasing the size of the breeding flock. The objective of this experiment was to investigate the effects of three different dietary CP intakes (96.8, 117 and 130 g CP/kg, low, medium and high respectively) on fertility in young and old male broiler breeders using some old and more recent fertility measures in an attempt to determine whether it would be justified to feed males a separate ration. Results showed that across all male ages no significant response in body weight (BW), sperm concentration and sperm mobility to dietary CP intake were seen. Although in the young males, birds on the high CP intake showed significantly (P<0.05) lower mean BWs than males on the low and medium CP intakes, and sperm mobility values were seen to be highest in birds receiving the medium CP intake across all male ages. The log number of inner perivitelline layer (IPVL) sperm holes was seen to increase with increasing CP intake (P<0.001) in males between 42 and 62 weeks of age (WOA) but showed no response in males from 27-41 WOA. The log number of IPVL sperm holes was seen to generally decrease with age in males from 27-60 WOA; however eggs collected two days postartificial insemination (PAI) had a similar log number of IPVL sperm holes, regardless of treatment, throughout the study. The mean number of IPVL sperm holes was seen to decrease as days PAI increased. There was a tendency for a superior response in fertility, predicted from IPVL sperm holes, from birds on the medium protein intake.
The effect of education on smallholder pig farmers' knowledge, practices and pig productivity in the Angónia District, Mozambique.
(2015) Alfredo, Zeiss Lacerda.; Ciacciariello, Mariana.; Mejer, Helena.; Tyler, Nicola Claire.
Smallholder pig production provides an important contribution for farmer livelihoods in many African developing countries. However, there are many constraints that limit pig performance and thus financial outcome. The present on-farm trial was carried out from June 2011 to September 2012 in four villages in the Angónia district, Tete province, Mozambique. The aim was to evaluate the effectiveness of pig health, housing, feeding and reproduction education of smallholders pig farmers on the knowledge uptake, changes in pig management practices and performance of sows and their offspring. All four villages were taught pig health and housing, but information on either feeding, reproduction or feeding and reproduction was also provided to each of three villages. The education was provided through an initial focussed group discussion followed by a collective and participatory training session. In addition, construction of a good quality pig pen was demonstrated in each village and throughout the study farmers received on-farm knowledge reinforcement. For evaluation of knowledge and practices, pig farmers (total across the villages: n=179) were tested using a semi-closed questionnaire and on-farm observation pre-education (baseline, month zero) and posteducation (month thirteen). Reproduction data from sows (n=125) and production data from their progeny (from birth until 8 months age, n=461) were collected from June 2011 to June 2012. Overall, 58% of the sows could be monitored to the end of the study. Overall high and significant proportions of farmers demonstrated knowledge uptake but the changes in practices were more modest except for pig pen quality, which improved substantially. The only significant change in pig productivity was an increase in the number of litters per sow in only one of the two villages taught reproduction. Unfortunately, this was countered by high piglet mortality so the number of weaned piglets was the same as in the other villages. It is concluded that, though education can induce substantial knowledge uptake by smallholder farmers, it is more difficult to change their practices. This was probably in part due to lack of resources, but overall with just a little change there is a potential for improving pig performance.
The effect of photoperiod after photostimulation on male broiler breeder fertility.
(2008) Floyd, Megan Helen.; Tyler, Nicola Claire.
Fertility in male broiler breeders may be controlled through a number of different methods, including lighting programmes. Currently in the poultry industry, male and female broiler breeders are reared under the same lighting conditions, as it is assumed that the males respond to light in a similar manner to females. However, the response to degree of photostimulation has not been as fully investigated in males as in females. The effects of different degrees of photostimulation, applied at 20 weeks of age, on the age at sexual maturity and the semen characteristics of male broiler breeders at the time of female sexual maturity, testosterone concentrations, secondary sexual characteristics and sperm-egg interactions were investigated. Results showed that males did not respond to light to the same extent as that seen in female boiler breeders, as ASM was not significantly affected by the degree of photostimulation applied as the males had probably spontaneously started spermatogenesis before photostimulation. This suggests that males could be photostimulated at a younger age than their female counterparts. A large amount of variation in individual male responses to degree of photostimulation was seen and this was possibly due to genetic variation as a result of selection pressure for meat and not fertility traits. Comb area was affected by the testosterone concentration and age but was found to be unrelated to semen characteristics. Semen characteristics were generally not affected by the final photoperiod apart from the semen concentration measured at female ASM. At 51 weeks of age, testes weights were affected by the degree of photostimulation with a trend of lower testes weights from birds on longer photoperiods which suggests the earlier onset of adult photorefractoriness in birds on longer photoperiods. Both testes and comb regression was evident by 51 weeks from at least one bird on each treatment which is concerning for the breeder industry where birds are usually kept for 60 weeks. The numbers of sperm trapped in the perivitelline layer of a hen’s egg, and the probability of the egg being fertile, were significantly affected by the photoperiod, age of the male and the time elapsed between artificial insemination and the laying of the egg. The impact of the degree of photostimulation on male broiler breeder fertility is an important topic for the poultry industry and is discussed.
The effects of dietary crude protein on fertility of broiler breeder males.
(2010) Waltsleben, Stephanie Lisa von.; Tyler, Nicola Claire.; Ciacciariello, Mariana.
Fertility of Broiler Breeders (BBs) has been researched over many years with inconclusive findings. Genetic selection and improvements in growth traits have had negative effects on fertility of BB. One explanation is related to overweight birds, resulting in the inability of birds to copulate successfully, with no cloacal contact. The requirements of CP for egg production in BB females have been quantified, but there is less literature on how CP affects fertility in male BBs. The objective of this experiment was to investigate the effects of feeding BB males different dietary CP intakes (10.4, 12.4, 14.2, 17.8, 19.3 and 20.1 g CP/bird/day) on fertility in flocks with natural mating and in birds that were artificially inseminated (AI). Results showed that birds consuming 10.4 and 12.4 g CP/bird/day resulted in weight loss (between 24.9 and 23.6% and 26.5 and 22.4% below target BW) over the 29 weeks of the experimental period in both natural mating and individual pens respectively. Intakes of higher protein content (17.8- 20.1 g CP/bird/day) however resulted in BW gain over the experimental period. Hatch percentage across all CP intakes throughout the duration of the study was found to be high, ranging between 75- 100 and 80-95 % in AI and naturally mated birds respectively, and not affected by CP intakes. Similar results for predicted fertility using the methods published by Brillard & Antoine (1990) and Wishart (1997) were found; however Brillard & Antoine (1990) is more lenient requiring less outer perivitelline layer (OPVL) sperm/mm2 to pronounce an egg fertile. Improved fertility predictions could have been made by using examination of inner perivitelline layer (IVPL). There was a tendency for a superior response in predicted fertility from birds with a protein intake of 14.2 g CP/bird/day. This intake also least affected the BW of the male birds and thus 14.2 g CP/bird/day can be recommended for optimal BB male performance.
The effects of maternal dietary lysine intake on broiler breeder offspring performance.
(2011) Khetani, Thamsanqa Lucky.; Ciacciariello, Mariana.; Tyler, Nicola Claire.
The aim of this study was to evaluate the effects of broiler maternal dietary lysine intake on progeny performance. Three experiments were conducted with chicks hatched from Cobb 500 breeders at 38, 48, and 60 weeks of age. Breeder hens received six dietary treatments (T1-T6) from 26 to 60 weeks of age, which allowed an intake of 800, 930, 1070, and 1200 mg lysine/bird/d (T1-T4) respectively. An intake of 800 mg/bird/d at 26 weeks was increased by 25 mg every two weeks to provide 1225 mg lysine/bird/d at 60 weeks (T5). An intake of 1200 mg/bird/d at 26 weeks was reduced by 25 mg every two weeks to supply 775 mg lysine/bird/d at 60 weeks (T6). A total of 320, 401, and 390 chicks were hatched from breeder hens at 38, 48, and 60 weeks of age respectively. Immediately after hatching, 270, 384, and 384 unsexed chicks from breeder hens at 38, 48 and 60 weeks of age respectively, were placed in an environmentally controlled room and randomly allocated (within a treatment) to single-tier cages (80 × 50 cm). Nine chicks from breeders at 38 weeks of age and 8 chicks from breeders at 48 and 60 weeks of age were placed in each pen, keeping chicks from the same treatment group together for 21 d. Chicks were fed ad libitum with a commercial broiler starter crumble for 21 d and water was provided ad libitum throughout the duration of each trial. Feed intakes (FI), body weight gain (BWG) and feed conversion ratio (FCR) were measured weekly. Data were subjected to analysis of variance using a generalized linear model of GenStat 12th edition. Simple linear regression model of GenStat 12th edition was used where appropriate. Significant improvements in offspring feed intake and body weight gain from 7-21 d were observed in chicks hatched from young breeder flocks (38 weeks) with low dietary lysine intakes (800, 930 and 950 mg/bird/d). The effect of maternal dietary lysine intake on offspring performance disappeared with the aging of the breeder flock (60 weeks). It was concluded that lower maternal dietary lysine intakes (800, 930 and 950 mg/bird/d) may improve feed intake and body weight gain from 7-21 d of broiler chicks hatched from younger breeder flocks (38 weeks).
An investigation of MSC Agric completion times at the University of KwaZulu-Natal.
(2014) Tyler, Nicola Claire.; Searle, Ruth Lesley.
There is a pipeline of production of PhD graduates, and any blockages in the pipeline will result in delays in the country achieving the target of about a 5-fold increase in the number of PhD’s, suggested by the Department of Science in Technology in their ten year plan to drive South Africa’s transformation towards a knowledge-based economy. To increase the pool of students capable of PhD studies, the pipeline issues, such as time taken to graduate by master’s students, need to be addressed. Therefore this thesis sought to review literature associated with throughput, dropout and completion times, determine whether any of the available information from graduated MScAgric students could identify factors that promoted or impeded timeto- completion, and determine the views of supervisors of MScAgric students on their role in the supervisory process. While this thesis did not assess “quality” of MscAgric students in any way, it is acknowledged that this is sometimes in tension with time-tocompletion and that in order for students to acquire the necessary skills, especially if they are to continue with doctoral studies, time-to-completion may need to be extended. Results showed that between 2000 and 2012, 67% of full time and 56% of part time students took longer than the minimum to complete. The only variable that significantly affected time-to-completion was full time versus part time registration, where, on a full-time equivalent basis, full time students took longer. Cum Laude passes were obtained by those who had significantly higher matric score, undergraduate weighted average and final year of undergraduate weighted average, and significantly more White students passed cum laude, however they tended to take longer to complete. Supervisors views related well to the guidelines suggested by the University and supervisors appeared to acknowledge responsibility for roles allocated to them Irrespective of post level, experience in supervising MScAgric or PhD students, or whether they had attended seminars or workshops relating to supervision, supervisors viewed their roles in the process relating to the topic, the thesis and the supervisor-student relationship, in a similar way, with no differences in opinion on whether particular responsibilities within these categories were those of the student or supervisor. The exception to this was observed where lack of supervision experience resulted in differing perceptions on the role of terminating the candidature and initiation of frequent meetings, both of which could result in longer times to completion of MScAgric students.
The photoperiodic response of male broiler breeders.
(2010) Tyler, Nicola Claire.; Gous, Robert Mervyn.
The expression of photorefractoriness, a feature of seasonal breeding in birds, is important in production species, where egg production and fertility are affected by the photoperiod. Years of selection in meat-type birds have reduced the potential reproductive function, and the environmental manipulation of such genotypes is essential to maximise productivity. While it is known that egg-type pullets no longer exhibit photorefractoriness, and that female broiler breeders do, there is not much information about the response of male broiler breeders to photoperiod. Such information is important when designing lighting programmes for breeding stock, and this study aimed to gain more insight into the male response to photoperiod. A series of experiments was designed in order to achieve this. In the first the response of male broiler breeders to rearing on constant photoperiods was measured, and in the second the effects of age at photostimulation on age at sexual maturity were assessed. The response to an increase in photoperiod during the production cycle was investigated in the third trial. Evidence of photorefractoriness in males was observed, but this was not the case in all birds, possibly due to high variation in some of the fertility traits measured. It seems possible that males do not respond to photoperiod to the same extent as females. Unexpected observations of a response in some birds to early photostimulation, and the high variation observed prompted another experiment in which the heritability of the response to early photostimulation was measured as a potentially revolutionary method of selection, whilst checking that this response is not negatively linked to broiler growth rates. Left and right testis weight data, collected in the above experiments, were analysed for asymmetry. There was no consistent response in testes asymmetry to photoperiod, or evidence that asymmetry in testis weights is as a result of the imposition of genetic or environmental stress. The strong correlation found between testes dimensions and weight suggests that predictions of testis weights could be made through ultrasonics or laparoscopy.
The response of broiler breeder hens to dietary lysine : hatchability, embryo growth and subsequent offspring performance.
(2011) Ruck, Shaun Bernard.; Tyler, Nicola Claire.; Ciacciariello, Mariana.
This study was conducted to determine the effects of breeder hen dietary lysine on offspring performance. In trial 1, Cobb 500 broiler breeder hens were fed 1200, 1070, 930 and 800 mg lysine/bird/d from 26 to 60 weeks of age or provided a gradual decrease from 1200 to 800 mg lysine/bird/d or a gradual increase from 800 to 1200 mg lysine/bird/d. Feed allocation was constant for all treatments at 160 g/bird/d. From each of these treatments 84 eggs were collected at 38,48 and 60 weeks of age and incubated. The different lysine treatments did not have a significant effect on the percentage hatch of the eggs at any of the recorded ages. However, hatchability, unexpectedly, decreased linearly with increasing dietary lysine, although the R2 for this was low. In trial 2, the effect of the maternal dietary lysine intake on the egg weight, yolk and albumen weights, embryo heat production and embryo growth rates of three genotypes (broiler, broiler x layer, and layer) and growth rates were assessed. The hens were fed either 920 mg lysine/bird/d (medium) or 816 mg lysine/bird/d (low). From each group 60 eggs were collected, weighed and then incubated. During the incubation from d 2 to d 18, 3 eggs were removed from each group every 2 d for eggshell temperature measurement and embryo weight measurement. There was a significant effect of lysine level on the embryo heat production of the broiler genotype with the birds from the high lysine treatment producing more heat and attaining a higher d 18 embryo weight. In trial 3, once the chicks had hatched, chick weight was recorded at 1, 7, 14, 21, 28 and 35 d. The chicks received a commercial starter and grower feed ad libitum. The broiler progeny from the birds on the high lysine treatment remained significantly heavier until d 14. The results indicate that an increased maternal lysine level improves the performance of a faster growing genotype up to 14 d of age.
A retrospective study of in situ and in vitro considerations in horse nutrition management.
(2017) Wiid, Catherine Lorna.; Tyler, Nicola Claire.
The current changes occurring in equine feeding management to meet performance demands, do not take into consideration the repercussions on the digestive tract. The aim of this investigation was to determine the linkage between nutrient intake, gastro-intestinal pH and gut mucosa, the impact on digestibility with changes in nutrient intake, age and mucosal damage and whether the current IVGPT protocol is an accurate reflection of in vivo digestibility. Post mortem work was carried out on samples of 27 sport and leisure horses shot for mechanical failure and financial reasons for an in silico analysis of nutrient intake and digestibility. A relationship was found between stomach ulceration and gut pH. There is no correlation between ulceration and digestibility but rather between nutrient density and digestibility. This shows that by increasing the concentrate portion of the feed may improve performance but has health impacts on the horse. IVGPT experiments were also conducted with faecal inoculum of race and idle horses over 3 buffer pH levels using maize and Lucerne as substrates. The results showed the significance (P<0.001) of buffer pH levels across treatments which indicates that fermentation protocols in equine IVGPT need to adjust buffer pH from 7.2 to 6.5.
The effect of dietary crude protein, organic selenium and vitamin E on fertility and semen quality of broiler breeder males.
(2008) Bekker, Hester Aletta.; Tyler, Nicola Claire.; Gous, Robert Mervyn.
There are negative influences of selection for broiler growth on the reproductive ability of broiler breeder parents. This is mostly due to problems related to excessive body weight, such as an inability to achieve successful cloacal contact during natural mating. There is also an age-related decline in fertility of broiler breeders. In attempts to prolong the fertile period of the breeders, various forms of management techniques have been employed. These include tools such as feed restriction, photoperiod management, spiking, and possibly even using artificial insemination. The first objective of this thesis was to investigate the possible benefits of feeding broiler breeder males diets containing lower crude protein levels, than given to the females, as a means of possibly tempering growth rate or improving semen quality and fertility. There was a definite improvement in the ability of the spermatozoa of the males on a lower crude protein diet to survive in the female reproductive tract. Males that received higher levels of crude protein were at a disadvantage in that fewer males yielded semen in response to abdominal massage. The second objective of this thesis was to assess the possible benefits in semen quality and fertility, when supplementing the male diets with additional vitamin E or Se in the form of Sel-Plex®. No significant effect of treatment was observed on egg fertility or semen quality.
To determine the impact of dietary calcium from dairy, and/or total dairy intake on the body mass index of Grade 2 leaners in Pietermaritzburg.
(2018) Galliers, Joanne Louise.; Wiles, Nicola Laurelle.; Tyler, Nicola Claire.
Introduction: International and local figures show a steep rise in the incidence of overweight and obesity in both adults and children, with more children suffering from overweight, obesity and their associated diseases of lifestyle than ever before. The aetiology of overweight and obesity is complex, with many interrelated factors involved. The South African government implemented the Food Based Dietary Guidelines in an attempt to guide the public on making healthy food choices. One of the guidelines encourages the public to “have milk, maas or yoghurt every day” due to the beneficial health effects of these dairy products. South African studies investigating the calcium intake of different age groups have shown children to consume inadequate amounts of calcium. A recent national survey showed the age group of 7 to 8 years old in particular, to have the lowest calcium intake of all age groups studied. Several international studies have shown dairy products, and specifically milk, to have an inverse relationship with Body Mass Index (BMI) in both adult and paediatric subjects. However, other international studies have provided conflicting results. No such study has been conducted in South Africa, and so the need arose to investigate a possible association between dairy products and childrens’ BMI. Aim: To determine the impact of dietary calcium from dairy and/or total dairy intake, on the body mass index of Grade 2 learners in Pietermaritzburg. Objectives: To determine the following regarding Grade 2 learners: the prevalence of overweight and obesity by interpreting their BMI; their calcium intake from dairy, and their total dairy intake; the contribution of dairy products to meeting their calcium requirements; whether a relationship exists between their dietary calcium (from dairy), and/or total dairy intake and their BMI; and possible barriers to dairy intake. Method: A cross sectional study was conducted on 91 Grade 2 learners from quintile 5 (fee-paying) schools in Pietermaritzburg. A three-part questionnaire, comprised of an anthropometric section, demographic questions, and a semi-quantitative food frequency questionnaire (FFQ) were administered to the parents/guardians of the Grade 2 learners. The BMI of the learners was compared to both the World Health Organization (WHO) and International Obesity Task Force (IOTF) classifications for overweight and obesity. The calcium intake was obtained from the FFQ, and compared to the Estimated Average Requirement (EAR) for calcium for 4 to 8 year olds. The dairy intake was also determined, and compared to the recommended national guidelines. Results: The study population comprised 57% female and 43% male learners, of whom 40.7% were Black African, 27.5% were White, 17% were Indian and 13.2% were Coloured. Of these learners, 28.6% (WHO) and 24.2% (IOTF) were overweight and 19.8% (WHO) and 15.4% (IOTF) were obese. More female learners were overweight than male learners, but a greater percentage of male learners were obese than female learners. Calcium intake from dairy was significantly below the EAR of 800 mg per day for 75.8% (n=69) of learners, with the average intake from the FFQ recorded as 615.2 mg. The mean number of dairy servings per day was 2.03, also below the recommended number of 3 servings of dairy per day. No relationship between BMI and calcium, or BMI and total dairy intake was established. Despite the low intake of dairy, no significant barriers to the consumption of dairy were identified. Conclusion: Grade 2 learners do not consume enough dairy products in their diet, and are therefore unable to meet the calcium requirements for their age. Greater effort is required by government, schools, health professionals and parents/guardians to promote, and encourage children to consume more dairy products. Further research on this topic is recommended, where the impact of lower fat and sugar containing dairy products on body fat (as opposed to BMI) can be investigated.