Simulation modeling is an active part of animal nutrition. These complex programs rely on mathematical functions to predict the performance of an animal. The Gompertz equation is a simple, but accurate function that fits animal growth data well. In conjunction with allometry, the growth of a specific genotype can be predicted. Only three parameters are needed to sufficiently describe a genotype, viz. protein weight at maturity (Pm), the Gompertz growth rate parameter (B) and the lipid to protein ratio at maturity (LPRm), These descriptors are lacking for commercial pig genotypes in South Africa, and this hinders the use of models in simulating nutrient requirements. It is the aim of this thesis to estimate these parameters in six South African pig genotypes. Thirty pigs from each of six commercial genotypes were analysed using a serial slaughter method in which pigs were slaughtered at 4 and 14 days of age, and at 30, 40, 70, 80, 90 and 100kg live weight. The animals were choice fed and were housed in conventional housing facilities. Analyses for protein, lipid, water, and ash contents of the empty body at the respective weights were performed. The results indicated that there were no significant differences between the six genotypes in terms of mature weights or B of the various body chemical components, or between the B values estimated for all components across genotypes. The mean of the estimated values for Pm, B and LPRm were 38,8 ± 2.1 kg, 0.012 ± 0.004 day(-1), and 1.16 kg/kg respectively and can therefore be used to adequately describe all six genotypes. The assumption made that all body components have a similar B value is supported. To investigate the possible effects of the environment on growth, a comparative trial was performed on 20 pigs each from genotypes 4, 5 and 6 using chambers in which the temperature could be controlled to within 1 degree C of the setting. All other experimental methodologies were similar to those adopted in the first experiment. No significant differences were found between the two housing facilities, in terms of the genetic parameters, within the respective genotypes supporting the findings of the previous trial. It may therefore be possible to estimate B using the live weight and estimating Pm and lipid at maturity using allometry, instead of going to the expense of a full serial slaughter trial. The allometric coefficients relating lipid, water and ash to protein were 1.18, 0.88 and 0.97 respectively. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.

The broad objective of the study was to determine feeding behaviour and gut health of pigs fed different fibres at varying inclusion levels. Maize cob, maize stover, sunflower hulls, veld grass, sawdust, lucerne and dried citrus pulp were used in growing and finishing pig diets to provide a wide range of physicochemical properties. Time spent eating, drinking, lying down, sitting/standing and other activities was observed using video cameras. Blood samples were collected at the end of the trial for both growing and finishing pigs for analysis of glycated haemoglobin, albumin, globulin, total protein, creatine kinase, urea and uric acid. Intestinal segments were collected at the end of trial for growing pigs to determine mucosal architecture of the intestines. Digestible energy (DE), bulk density (BD), acid detergent fibre (ADF) and water holding capacity (WHC) were the most important variables predicting time spent on different behavioural activities in growing pigs (P < 0.001). Water holding capacity, neutral detergent fibre (NDF) and ADF were the most important variables involved in predicting time spent on different behavioural activities in finishing pigs (P < 0.001). Physicochemical properties influenced time spent on different behavioural activities and they provided relationships with time spent on different behavioural activities in both growing and finishing pigs. Glycated haemoglobin, albumin, globulin, total protein and uric acid were factors that influenced time spent eating in growing pigs (P < 0.05). In finishing pigs, only serum total protein was selected as the best predictor variable influencing time spent eating (P < 0.05). The blood metabolites were correlated with time spent eating and drinking. They provided threshold values with time spent eating and drinking by pig. Hence, they can also be used as potential biomarkers that modulate neuronal pathways which reduce time spent eating and drinking. In this study, bulk density (BD) and NDF were the best predictor variables influencing villi height (VH) and apparent villi surface area (AVSA) in pigs (P < 0.05). Grouped pigs fed fibrous diet spent more time eating, lying down, standing, walking and fighting (P < 0.05). Skin lesions appeared the most on neck and shoulder region followed by chest, stomach and hind leg region, and finally head region (P < 0.05). Fibrous diet did not reduce aggressive behaviours, rather aggressive behaviours emanated out of frustration when queuing at the feeder. It was concluded that physicochemical properties of fibrous diets and nutritionally-related blood metabolites influence feeding behaviour. Mucosal architecture was also influenced by physicochemical properties of the fibrous diets. / Ph.D. University of KwaZulu-Natal, Pietermaritzburg 2013.

A study was conducted to test the effects that different high fibre sources and their varying inclusion levels had on the characteristics of the excreta (faeces, urine and the slurry), and on odour from the slurry of growing pigs. Faeces and urine characteristics were tested from 52 pigs fed rations containing grass hay (GH), lucerne hay (LH), maize cobs (MC), maize stover (MS) and sunflower husk (SH) diets at inclusion levels up to 400 g/kg as fed basis. Faecal output, faecal consistency and nitrogen were influenced by fibre type (P <0.01) and inclusion level (P <0.01). Nitrogen content in faeces and urine was also affected by dietary fibre inclusion. Increasing fibre inclusion levelled to a reduction in urinary nitrogen content, indicating nitrogen repartitioning from urine to faeces, thereby minimizing nitrogen volatilization. The slurry from pigs fed on LH, MC and SH at levels up to 160 g/kg was tested for chemical composition and odour offensiveness. The slurry was incubated for 16 days. The pH and nitrogen content varied among fibre types and incubation period (P <0.05). Isobutyrate and butyrate concentrations varied with fibre type and the incubation period tested (P <0.01). Using panellists, the SH containing rations resulted in low odour offensiveness score. Maize cob-containing diets resulted in the largest odour scores, with (mean rank of 2.2 and 4.3 for SH and MC, respectively). To reduce odour offensiveness from piggeries, sunflower husk was recommended as an alternative feed ingredient for growing pigs. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

The broad objective of the current study was to determine the response of pigs fed on incremental levels of Acacia tortilis leaf meal-based diet. Eight trees of each of the following five dominant leguminous leaf meals; A. tortilis, A. robusta, A. nilotica, A. nigrescens and A. xanthophloea, were individually hand harvested from the same grazing camp at Makhathini Research Station, Jozini, South Africa. The leaf meals were harvested between April and May 2013 after the rainy season at advance stage of maturity. Following the nutritive evaluation of Acacia species, A. tortilis was selected for the feeding experiment. Thirty finishing male F1 hybrid (Landrace × Large White) pigs with an initial weight of 60.6 (s.d. = 0.94) kg were randomly allotted to six dietary treatments containing 0, 50, 100, 150, 200, 250 g/kg DM inclusion levels of A. tortilis leaf meal. Each treatment diet was offered ad libitum to five pigs in individual pens for 21 days. Average daily feed intake (ADFI), body weight, average daily gain (ADG) and gain: feed ratio was measured every week. Blood was collected at the end of the experimental period for the determination of nutritionally-related blood metabolites and activity of Aspartate aminotransferase (AST), alanine amino transferase (ALT) and alkaline phosphatase (ALP). Following a feed withdrawal period of 12 hours, pigs with a mean body weight of 80 ± 15 kg were slaughtered, eviscerated for the collection of livers, kidneys, lungs and heart from each pig and weighed individually using a digital scale. Acacia tortilis and A. xanthophloea leaf meals had the highest CP and fat content (P < 0.01) among all the Acacia species. The NDF and ADF varied significantly across Acacia species (P < 0.05). Acacia robusta had significantly the highest levels of non-structural carbohydrates, whilst A. tortilis had the lowest. The concentration of proanthocynidins varied across the species. Acacia tortilis had significantly high levels (23 g/kg DM) of phosphorus compared to the other species. Acacia nilotica had the highest (P < 0.001) concentration of iron, but it had the lowest (P < 0.01) level of manganese. There was a quadratic decrease in both ADFI and ADG (P < 0.001) with as A. tortilis leaf meal increased. The gain: feed ratio was linearly reduced (P < 0.001) with incremental levels of A. tortilis leaf meal in the diets. Serum concentrations of Fe, AST and ALP increased quadratically (P < 0.01) as A. tortilis leaf meal increased. There was a linear increase in ALT activity with increased leaf meal inclusion. Hepatosomatic index (HSI: liver weight/ body weight x 100), scaled kidney weight and scaled heart weight increased linearly (P < 0.001) as A. tortilis leaf meal increased. There was, however, a quadratic increase in the relative weight of lungs (P < 0.001) as leaf meal increased. In conclusion, the piecewise regression (brocken-stick) NLIN procedure (SAS, 2008; SASA institute Inc.) showed that A. tortilis leaf meal can be included in finisher pig diet up to 150 g/kg DM of feed without negatively affecting growth performance, nutritionally-related blood metabolites, liver enzymes and internal organs of pigs. / M.Sc.Agric. University of KwaZulu-Natal, Pietermaritzburg 2013.

MSCAGR (Animal Science) / Department of Animal Science / The study evaluated the nutritive value of orange pulp- buffalo grass (OPBG) silage as a po-tential pig feed. In experiment 1, OPBG was ensiled in 58 one-litre jars, split into Reno-zyme® enzymes (containing α-amylases and β-endo 1, 3; 1, 4 beta glucanase) (denoted OPBGE) and 18 without enzyme (denoted OPBG). Samples were collected from the lab on days 7, 15 and 30 in a three by two factorial design (period by treatment). In Experiment 2, 12 South African Windsnyer-type (SAWIP) (27.2±3.9 kg) and 12 Large White- Landrace crosses (LW x LR) (28±9.8 kg) were fed diets containing different levels of bulk-ensiled OPBG ad libitum for 30 days, in a 2 X 3 (breed by level of OPBG (control, low (15% OPBG) and high (30% OPBG))) factorial arrangement. The apparent total tract digestibility (ATTD) of the pigs was measured during week 3 of feeding. The average body gain ABG average daily feed intake (ADFI), average daily gain (ADG), average gain to feed ratio (AG: F) were measured weekly. Serum glucose (GLU) , blood urea nitrogen (BUN), creatinine (CREAT), cholesterol, (CHOL) and triglycerides (TG) were measured during week 4 of the experiment. The levels of CP, EE, NDF, water soluble carbohydrates (WSC), lactic acid (LA) and pH were different (P<0.05) for OPBGE and OPBG on day 7. However the OPBGE concentra-tions of DM, ASH, CP, NDF, HEMI, WSC, LA and pH were higher (P<0.05) compared to OPBG. The OPBGE was lower (P<0.05) on EE and ADF, compared to OPBG on day 7. The levels of DM, ASH, CP, NDF, ADF, HEMI, LA and WSC were different (P<0.05) for OPBGE and OPBG on day 30. However the OPBGE levels of DM, CP, NDF, ADF, LA and WSC were higher (P<0.05) compared to OPBG. ASH, EE and HEMI were lower (P<0.05) on day 30. There were significant diets x day interactions (P<0.05) for DM, ASH, CP, EE, NDF, ADF, HEMI, WSC, and LA, but not for pH. The aerobic stability study was inconclusive. The digestibility levels of OM and NDF were different (P<0.05) for LW x LR and SAWIP, where LW x LR ATTD on OM and NDF was higher (P<0.05) compared to SAWIP for all diets. The LW x LR ADG was higher (P<0.05) compared to SAWIP for all diets. There was a diet x breed interaction effect (P <0.05) on ADG whereby the BUN and CREAT were different (P <0.05) for LW x LR and SAWIP. The SAWIP BUN was higher (P<0.05), but the CREAT and TG were lower (P<0.05) compared to LW x LR for all diets fed. In conclusion, OPBG inclu-sion in pig feed enhanced the quality of feed, digestibility, performance and blood metabo-lites profile. / NRF

This study was conducted to compare the availability of Zn from two Zn sources, an amino acid chelate and ZnSO₄. In three experiments, 78 Zn depleted and 24 Zn adequate pigs were used. Pigs were depleted of Zn by feeding an isolated soy protein, semi purified diet containing 17 ppm Zn. Of the 78 depleted pigs, 60 pigs were Zn repleted. During Zn repletion in Exp. 1, depleted pigs were fed the low Zn diet supplemented with 5, 15, or 45 ppm Zn either as ZnSO₄ or as Zn amino acid chelate (ZnAAC). In Exp. 2 and 3, low Zn diets were only supplemented with 45 ppm Zn. Zinc adequate pigs, used in Exp. 1 and 2, were fed the 45 ppm supplemental Zn diets. To evaluate differences in site and rate of apparent Zn absorption, chromic oxide was added to the diets of depleted pigs in Exp. 1 and 3. In all experiments, a 24-d period was sufficient to severely deplete the porcine body Zn stores, and to cause parakeratosis and growth retardation. Serum Zn concentrations and serum ALP-activities of depleted pigs dramatically decreased (P < .01) during the first 14 d of Zn depletion. At the end of Zn depletion, Zn contents in liver, kidney, pancreas, brain, and small intestine tissues of pigs fed the low Zn diet were reduced (P < .01) by 10 to 40 % compared with the adequate pigs fed the ZnSO₄ and ZnAAC diets. In Exp. 2, the growth retardation was associated with a low (P < .05) serum mitogenic activity and pituitary RNA content of depleted pigs compared with pair-fed adequate pigs. Moreover, the growth hormone mRNA fraction tended to be reduced (P < .10) for the Zn depleted pigs. In Exp. 1, the apparent absorption of Zn was higher (P < .01) for pigs fed ZnAAC compared with the ZnSO₄ group; however, this was not confirmed in Exp. 3 unless coefficients were corrected for Cr recovery. Furthermore, absorption of Zn occurred primarily within jejunal and distal segments of the small intestine. In the balance of Exp. 3, disappearance rates of Zn, Cu, Fe and DM were higher (P < .01) in depleted pigs fed ZnAAC compared with ZnSO₄. The recovery of Cr also was different (P < .01) between pigs fed the ZnSO₄ (87 %) and ZnAAC (70 %) diets. Moreover, the moisture content of the fecal matter was 11 % higher (P < .01) for the ZnAAC group compared with pigs fed ZnSO₄. In Exp. 1, depleted pigs fed the 15 ppm ZnSO₄ and ZnAAC diets regained their ability to grow, however, replenishment of body fluid and tissue Zn pools did not occur within the 24-d Zn repletion period. Both the 5 ppm ZnSO₄ and ZnAAC groups did not respond to Zn repletion within a 12-d period. In all experiments, the rate and degree of repletion of body fluid and tissue Zn stores was not different between pigs fed the 45 ppm ZnSOq and ZnAAC diets, although a higher (P < .05) serum mitogenic activity was observed for the adequate pigs fed ZnAAC compared with ZnSO4. In conclusion, an amino acid chelate did not improve growth, or rate and degree of replenishment of body fluid and tissue levels of Zn compared with pigs fed ZnSO₄. However, ZnAAC may have influenced intestinal luminal conditions since a higher rate of disappearance of Zn, Cu, Fe, Cr, and DM was measured. / Ph. D.

This study was done in the rural areas of uThukela District in KwaZulu-Natal. The objectives were to determine pig production and management practices used by farmers in rearing pigs in rural areas; to establish the role of pigs in social and economic lives of the people; and to characterize and determine constrains and opportunities of pig farming in rural areas. A farming systems approach was used in conjunction with a cross-sectional survey method using a structured questionnaire in face-to-face interviews with farmers for the collection of data. The study involved 4 local rural municipalities with a population of 4205 people who owned 2555 pigs. The sample size was 533 pig farmers/respondents. The data included the demographic characteristics of pig farmers, pig production and management practices, the role of pigs in both the social and economic lives of people and the constraints and opportunities of pig farming. The data were analyzed to determine simple means and frequencies. The results showed that 20% of pigs were reared in intensive systems and 80% in extensive systems in the district. Each village owned an average of 5 pigs. There were more female respondents (60%) than males, and also female respondents owned more (65%) pigs than males. Most of respondents (99%) were Zulu speaking people and only 1% was from other cultural groups. Majority of the respondents (74%) were unemployed, 16% were pensioners and only 10% were employed. Those who were employed kept more pigs than the other groups. Over one third of the respondents had primary (34.5%) and secondary (35.3%) education; and 2.7% had college education, while 27.5% had no formal education at all. Sixty-two percent of the older respondents between the age of 46 and 65 years kept more pigs than younger farmers. The collective incomes of the communities from salaries, pensions, and sales of livestock and crops per annum were substantial. The average land size per household ranged from 0.01 ha to 56 ha. Male respondents owned more land (1.68 ha) than female respondents (0.96 ha). Similarly, employed people owned more land (2.49 ha) than pensioners (1.26 ha) and the unemployed people (1.04 ha). Respondents kept other livestock species such as cattle, sheep, goats and chickens. Ninety percent of households kept chickens in addition to cattle (53%) and goats (49.3%). They also grew crops such as maize, potatoes, vegetables (cabbage, spinach, tomatoes, carrots, beetroots and onions) and fruits (peaches, apples and grapes). They kept pigs for home consumption (63%), source of income (33%), source of manure (3%) and for other reasons (1%). More employed people (68%) sold pigs for extra income, while 91% pensioners and 81% unemployed people used pigs for home consumption. Marketing channels included pension pay points, abattoirs, butcheries and neighbourhoods. Abattoir sales accounted for 10% and the most common venues were Amblecyte (40%) and Cato Ridge (27%). Selling of pigs occurred throughout the year, with the peak in winter (May/July). Majority of farmers (59%) used their own transport to deliver pigs to the selling points or they used contractors (41%). Pigs were sold at the age of 5 to 18 months old. Farmers sold live pigs and pork to the communities. Some farmers sold live pigs only, while others sold pork only or both pork and live pigs. Religion and culture had little influence on pig farming. Most farmers (88%) had no religious or cultural influences, while 7% were influenced by religion and 1% was influenced by culture. The most preferred meat among the communities was chicken meat, followed by beef, pork, mutton and chevon. Half of the respondents had >6 years of experience in pig farming, 34.9% had 2 – 5 years of experience and 14.8% were beginners. The breeds of pigs kept in the district included indigenous breeds, Large White, Landrace, Duroc and crosses of indigenous breeds with Large White and Landrace. Farmers bought breeding stock within their communities or they selected breeding stock from their own herds. Very few farmers have ever received any type of training in pig farming. The training was provided by the KZN Provincial Government, Zakhe Agricultural College and private farms. The training took 2-3 days of workshops, 2-3 weeks of short courses or 3-6 months of hands-on training on private farms. The training improved the performance of sows within the communities. Only 41% of farmers practised controlled stock breeding, which improved the farrowing rate and litter size. About one third (32%) of farmers bred their gilts at 6 – 8 months, while 21.2% bred them at 8-12 months, and 29% bred them after 12 months. The farrowing rate of indigenous sows was one litter per annum compared with the majority of Landrace and Duroc sows that farrowed twice a year. Some farmers (28%) reported that they routinely observed farrowing, while 72% of them said they never knew when the sows farrowed until they saw sows and new litters coming back to their pens after grazing in the veld. The litter sizes varied from ≤ 7 to ≥ 10. Half of the indigenous sows farrowed ≤ 7 piglets per litter, while 41% had 8-10 piglets; compared with 49% Large White and 44% Duroc that farrowed 8-10 and ≥ 10 per litter, respectively. Majority of farmers (66.1%) did not wean their piglets at all, which was associated with low farrowing rate. However, farmers who sold weaners for income weaned their piglets between 3 weeks and 3 months. This was associated with higher farrowing rate of sows. Piglet mortality was mainly due to worm infestation (26%), loss of hair (13%), lice and mange infestation (16.4%) and diarrhoea (5.6%). Despite that only 10% of farmers consulted the local Department of Veterinary Services. Some farmers (44.2%) said that they did not know that they could make use of Veterinary services, and 28% of them said it was a waste of time. Majority of farmers (80%) used home kitchen swill and brewer’s grains to feed their pigs. Only 16% of farmers bought commercial feeds and 2% fed them on maize grains and vegetables. Commercial feeds were bought from Farm Save (48%), Afgri (19%) and Epol (7%). Some farmers (65.4%) weighed feed before feeding, while 35% did not weigh feed at all. Water was provided at feeding time, ad libitum or several times a day. Farmers disposed of carcasses by eating them, feeding to their dogs, or throwing them away. Over half of the farmers (52%) did not take carcasses for post mortem, while 26% did not know that they could send carcasses for post mortem and 20% said they could not afford the cost. The study concluded that pigs have a vital social and economic role in the lives of the rural people of KZN for income generation and household consumption. The main constraints are wide spread poverty and lack of management skills in pig production, nutrition, health,housing and management. Government intervention is necessary to help farmers to improve pig production and management as a means of poverty alleviation and household food security. / Agriculture and  Animal Health / M.Sc. (Agriculture)

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2005. / The demand for protein for human and animal nutrition in South Africa is increasing and it will continuously increase. The effect of replacing soybean oilcake meal as protein source for broilers and full-fat soybean meal for weaner pigs, with different levels of sweet lupins (Lupinus angustifolius), canola oilcake and full-fat canola was examined. A basal diet with soybean oilcake as protein source was mixed with a diet using either sweet lupins or canola oilcake or full-fat canola in ratios of 100%, 67% and 33% respectively. In the broiler trial the test diets were fed for a period of six weeks with or without the enzyme Vegpro (Alltech). Pigs were fed the test diets, with and without Roxazyme® enzyme, ad libitum from 8.5 to 25 kg live weight. The fatty acid content of the fat pads of the broilers raised on the different diets was determined. The pigs were kept in the trial up to the grower- finisher phase. The fatty acid content of the carcass fat and muscle of pigs raised on the different diets was determined. The inclusion of enzymes had no effect on the growth, feed intake or feed conversion ratio of broilers fed the test diets. The provision of external dietary enzymes to the weaner pig diets failed to improve either dry matter intake or growth rate, but improved the feed conversion ratio. Broiler weights at six weeks of age were significantly higher for the control diet compared to the 20% lupin diet. There was no significant difference in the feed intake as the lupin content of the diets increased. The feed conversion ratio did not differ significantly between the control diet and the 6.6% lupin diet but became significantly poorer as the lupin content increased to 13.2% and 20% of the test diet. There were no significant differences in production performance of the control diet and the canola oilcake containing diet. The broiler weights at six weeks decreased significantly with each increase in the canola oilcake content of the diets. The feed intake of the 20% canola oilcake diet at week six was significantly less than the intake of the control diet, but not significantly less than the 6.6% and 13.2% canola oilcake diets. The feed conversion ratio of the control diet was significantly better than the 13.2% and 20% canola oilcake diets. No significant differences were found in week six between the 6.6% full-fat canola diet and the control diet for broiler weights and feed intake. The feed conversion ratio of the broilers fed the 13.2% and 20% full-fat canola diets was significantly poorer than the control diet. The final body weights of the weaner piglets fed the control diet were significantly higher than the final body weights of weaner piglets fed the lupin containing diets. The average daily gain of the weaner piglets fed the control diet was significantly higher than the gain of the weaner piglets fed the lupin containing diets. No significant differences in the feed intake and feed conversion ratio between the different lupin inclusion levels were detected. There were no significant differences in body weight, feed intake, average daily gain and the feed conversion ratio, between the various full-fat canola containing diets and the control diet. A significant difference in body weight was found between the weaner piglets fed the 20% canola oilcake diet and the weaner piglets fed the control diet. There were no significant differences in feed intake between the various inclusion levels of canola oilcake. The control and 6.6% canola oilcake containing diets had significantly higher average daily gains than the 20% canola oilcake containing diet. In the final trial the finisher pigs fed the test diet containing 25.00% lupins, had a final body weight significantly lighter than the final body weight of the finisher pigs fed the other test diets. The finisher pigs fed the test diet containing 25.00% lupins, also had a significantly reduced average daily gain and feed intake. The feed intake of the 25.00% canola oilcake diet was significantly lees than the feed intake of the 16.75% full-fat canola containing diet. The feed conversion ratio of the 25.00% lupin containing diet was significantly poorer than the feed conversion ratio of the 16.75% lupin containing diet, 8.25% lupin containing diet, 16.75% full-fat canola containing diet, 25.00% canola oilcake containing diet and the control diet. In a choice feeding trial growing pigs were offered four diets with four different protein sources: sweet lupins (25% inclusion level), canola oilcake (25% inclusion level), full-fat canola (25% inclusion level) and soybean oilcake (25% inclusion level), while their daily intakes were recorded. In a second choice feeding trial pigs were offered ten different diets with increasing levels (6.6%, 13.2%, 20%) of either sweet lupins, canola oilcake meal or full-fat canola meal. The pigs consumed significantly more of the soybean oilcake containing diet compared to diets containing the alternative protein sources. Pigs consumed significantly less of the full-fat canola diet compared to the sweet lupin and canola oilcake diets. Ten different canola cultivars were collected from two different locations in the Mediterranean rainfall area of South Africa namely the Western Cape (Swartland) and Southern Cape (Rûens) grain producing areas. The sinapine and glucosinolate content of various canola cultivars was compared and the influence of locality on the sinapine and glucosinolate content of the canola cultivars was determined. There were no significant differences (P < 0.05) in sinapine content when the canola produced in the Western and Southern Cape were compared. Varola 54 and Rainbow cultivars had significantly higher (P < 0.05) sinapine contents compared to the Varola 50 cultivar. Samples of lupins, field peas, faba beans and narbon beans were collected and analysed for amino acids, alkaloids, non-starch polysaccharides, tannin and starch. The digestible energy value of these alternative protein sources for pigs was determined. Significant differences were found in the amino acid content of the various crops. The alkaloid content of the lupins varied significantly between the sweet and bitter lupin varieties. Sweet L. angustifolius cultivars contained ca 50mg/kg and the bitter L. angustifolius cultivars ca 15000mg/kg alkaloids. The mean alkaloid content of L. albus cultivars was ca 1300mg/kg. The faba beans, narbon beans and peas had significantly higher values for tannins and starch, compared to lupins.

Two experiments were conducted for this thesis, to determine whether an animal should be fed to its genetic potential in spite of this not being achievable due to an on-farm constraint. The first experiment was designed to compare the response of pigs housed either individually or in groups to a range of feeds limiting in lysine between 40 and 85 kg live weight. Two hundred and eighty-eight entire male Large White x Landrace pigs were used. The experiment was divided into two growth periods, i.e. from 40 to 60 kg and from 60 to 85 kg. In each period, pigs were subjected to feed containing one of four dietary lysine concentrations. In Period 1, the lysine concentrations were 11.03 (L1); 9.54 (L2); 8.00 (L3) and 6.51 (L4) g/kg, while in Period 2 these were 7.82 (T1); 6.71 (T2); 5.55 (T3) and 4.40 (T4) g/kg. Pigs fed an L1, L2, L3 or L4 diet in Period 1 were fed a T1, T2, T3 and T4 diet in Period 2, respectively. Three buildings provided the following group sizes and floor-space allowances: House 1 contained eight pigs per pen at 1.94 m2/pig; House 2 contained four or eight pigs per pen at 1.72 or 0.86 m2/pig; and House 3 contained one pig per pen at 1.72 m2/pig. The individually-housed pigs were divided into three feeding levels, i.e. ad libitum, or pair-fed so that feed intakes would match those of ad libitum-fed pigs housed in groups of either 4 (restricted-4) or 8 (restricted-8) pigs per pen in House 2. For all group sizes, feed intake increased linearly as the dietary lysine content increased. However, this increase was significantly lower for 8, when compared with 1 and 4 pigs per pen. The linear increase in feed conversion efficiency with dietary lysine content was similar for all group sizes. However, at any dietary lysine concentration, pigs housed in groups of 8 had significantly higher efficiencies than the pigs housed individually or in groups of 4. Average daily gain increased linearly as lysine intake increased, this increase being the same for all group sizes. However, pigs in smaller groups grew significantly faster than those in larger group sizes for any lysine intake. Protein and lysine retention were unaffected by group size, increasing linearly as lysine intake increased. The efficiency of lysine utilisation (0.45) was not impaired by group size. The pair-fed pigs housed individually (restricted-4 and -8) consumed significantly less feed than the individually-housed pigs fed ad libitum, and this was reflected in their average daily gains, which increased linearly as lysine intake increased, but with the restricted-8 growing significantly slower than the ad libitum or restricted-4 pigs. In all three treatments feed conversion efficiency increased linearly with dietary lysine content, although the restricted-4 and -8 had significantly higher efficiencies than the ad libitum-fed pigs at any dietary lysine content. Protein and lysine retentions were unaffected by feeding level and increased significantly with lysine intake. However, at any lysine intake the restricted-8 pigs had a significantly lower efficiency of lysine utilisation than the ad libitum or restricted-4 pigs. The pigs with floor-space allowances of 0.86 and 1.94 m2/pig consumed significantly less and grew slower than the pigs with floor-space allowances of 1.72 m2/pig at any dietary lysine content. Feed conversion efficiency was unaffected by floor-space allowance and increased significantly with dietary lysine content. Similarly, protein and lysine retentions were unaffected by floor-space allowance and increased linearly as lysine intake increased. The efficiency of lysine utilisation (0.45) remained unaffected by floorspace allowance. It was concluded that when animals are socially stressed, feeding according to the requirement for maximum protein growth produces the best biological performance and carcass composition, with the corollary that, if profitability and biological efficiency is to be maximised, pigs housed in stressful conditions, or those whose future performance is predicted to be below potential because of external stressors, should not be given feed of an inferior quality. The second experiment was designed to determine the extent to which grouping or floorspace allowance would alter the nutrient content of feed chosen by pigs given a choice of two feeds differing in protein: energy ratio between 40 to 85 kg live weight. Three hundred and eighteen entire male Large White x Landrace pigs were used. Two buildings provided the following group sizes and floor-space allowances: House 1 contained nine and eighteen pigs per pen at 1.72 or 0.86 m2/pig; House 2 contained four, nine and fourteen pigs per pen at 1.72; 0.86 or 0.49 m2/pig. Animals were given simultaneous ad libitum access to a high (236 g protein/kg as fed) and a low crude protein feed (115 g protein/kg as fed) in two hardened plastic self-feeder bins placed side-by-side. A training period of six days was used prior to the start of the trial, during which the two feeds were alternated daily. The reduction in the proportion of high protein feed chosen over time was significantly higher for the groups of four and eight, in comparison to the groups of nine and eighteen, contrasting with the steady increase for the groups of fourteen pigs. Similarly, the significant increase for pigs with floor-space allowances of 0.49 m2/pig differed from the significant decrease for pigs with floor-space allowances of 0.86 and 1.72m2/pig. Pigs housed in larger group sizes and smaller floor-space allowances consumed significantly less and grew slower than pigs housed in smaller group sizes and larger floorspace allowances. However, the feed conversion efficiency remained unaffected by group size and floor-space allowance. The non-significant effect on protein retention with increasing group size contrasted with the significant increase associated with increasing floor-space allowance. The results of the two studies were compared to determine whether pigs chose differently depending on the degree of stress and the implication of this choice. Average daily gain was significantly reduced as the group size increased for pigs fed a fixed lysine content and choice-fed. However, this reduction was less severe with choice-feeding than when feeding a fixed lysine content. Increasing the group size significantly reduced the feed intake in pigs fed a fixed lysine content only. The efficiency of protein utilisation remained unaffected as the group size increased for the pigs fed a fixed lysine content. However, at any group size pigs fed lower lysine contents had higher efficiencies than pigs fed higher lysine contents. On the contrary, increasing the group size significantly increased the efficiency of protein utilisation in choice-fed pigs. The average daily gain and feed intake was significantly improved as the floor-space allowance increased but was similar for pigs fed a fixed lysine content and choice-fed. Although the efficiency of protein utilisation remained unaffected by increasing the floor-space allowance for the pigs fed a fixed lysine content and pair-fed, at any floor-space allowance pigs fed higher lysine contents had higher efficiencies than pigs fed lower lysine contents. The results indicate that providing socially stressed pigs a choice between an appropriate pair of feeds differing in protein: energy ratio, does not overcome the reduction in potential growth, but does result in performance similar to that of pigs fed a fixed lysine content. It was concluded that the social stress of grouping or floor-space allowance has no influence on the ability of the animal to select an appropriate dietary combination allowing the expression of potential growth within the constraint(s) of the production system. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

The broad objective of the study was to determine the economic value of local pigs in marketand subsistence-oriented production systems in communal areas of Southern Africa. Data were collected from 288 households to investigate farmer perceptions, effects on pig production and handling of disease outbreaks such as classical swine fever (CSF) in market- and subsistenceoriented production systems. The utilisation of local pigs in these market- and subsistenceoriented production systems in improving people‟s welfare was evaluated. Climate change was identified by farmers in these production systems as a major constraint to pig production hence an experiment was carried out in the hottest season to determine diurnal heat-related physiological and behavioural responses in Large White (LW) and South African local pigs. The same genotypes were used to determine effects of diurnal heat-related stress on their growth performance. Choice experiment was done to determine farmer preferences for local pig traits and implicit prices for these traits in CSF-affected and unaffected areas that were under subsistence- and market-oriented production systems. In this experiment, the importance of heat tolerance was assessed relative to other productive and climate change adaptation traits. Significantly more pigs were culled in the CSF-affected areas that were market-oriented (8.0 ± 1.76) than subsistence-oriented (4.1 ± 1.00) production system. The risk of parasites and disease challenges was high in subsistence-oriented production system and coastal areas. In both production systems, CSF was perceived as destructive since the culling of pigs affected pork availability and income generation. The high risk of disease outbreaks and threat of climate change caused farmers in subsistence-oriented production system to select local pigs for their adaptive traits while those in the market-oriented production system focused on productive imported pigs. Farmers (83 %) indicated that they wanted pig genotypes that were adapted to climate change effects such as hot conditions. Local pigs were found to have superior heat tolerance over LW pigs (P < 0.05) in terms of lower heart rate and skin surface temperature. Frequency per day and duration for behavioural heat loss activities such as wallowing, sleeping in a prostrate posture and sprawling in slurry were also lower (P < 0.05) for local than LW pigs. The superiority of heat tolerance of local over LW pigs was further confirmed by their uncompromised growth performance under high diurnal temperatures. The Pearson‟s product moment correlation coefficient between temperature and feed conversion ratio for LW pigs was strongly positive (r = 0.50; P < 0.001) unlike the weak and positive correlation for local pigs (r = 0.20; P < 0.05). There was a quadratic relationship between temperature and average daily gain (ADG) for both pig genotypes. The regression coefficients for ADG were higher (P < 0.001) for LW than local pigs. It was concluded that at high ambient temperatures, performance of local pigs was less compromised than for LW pigs. Although local pigs were found to be heat tolerant, results of choice experiment showed that this trait was not selected for relative to other traits. Keeping pigs that required bought-in feeds, fell sick often and produced low pork quality (eating quality based on farmer perceptions) negatively affected farmers‟ livelihoods more in subsistence- than market-oriented production system. Farmers in market-oriented production system derived more benefit from productive traits such as heavier slaughter weights and large litter size than subsistence-oriented farmers. Under the subsistence-oriented production system, farmers in CSF-affected areas placed high prices on adaptive traits than the unaffected areas. Subsistence-oriented farmers who were affected by CSF wanted a total compensation price of R10 944.00 (USD1563.43) for keeping a pig genotype with unfavourable traits when compared to R4235.00 (USD605.00) for their CSF-unaffected counterparts. Implicit prices for traits could not be determined for market-oriented production system. It was concluded that farmers in CSFaffected areas placed high economic values on pig traits than farmers from the CSF-unaffected areas. The findings suggest that adapted local pigs can be promoted in subsistence-oriented production systems while productive imported pigs and their crosses with local pigs can be kept in market-oriented production systems.