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<p>  </p> <p>We have a need to increase protein production as the world population continues to increase. Seeing that land and resources are a limited commodity, the need to raise pigs as efficiently as possible will continue to increase. Similarly, as the industry switches further away from antibiotics and growth performance technologies, the need for wholistic alternatives continues to increase. Therefore, the focus of this dissertation primarily focuses on technologies to improve pig growth performance both in the nursery (Chapter 3 and 4) as well as the finisher (Chapter 2 and 3). In chapter two, two experiments were conducted to evaluate the effect of β-mannanase and lysine level as well as β-glucanase and β-mannanase in combination during ractopamine feeding prior to market. In Exp. 1, 343 crossbred pigs were blocked by ancestry, sex, and initial BW (97.3 ± 1.36 kg) and allocated to mixed gender pens (5 or 6 pigs/pen) to 5 treatments with 10 or 12 pens/treatment. Dietary treatments included: 1) low lysine (0.80% SID Lys; LL); 2) LL+mannanase (0.08 MU/kg); 3) high lysine (0.95% SID Lys; HL); 4) HL+mannanase (0.08 MU/kg); 5) As treatment 3 + 4% choice white grease (CWG). Diets were corn-soy based (LL and HL=3335 and CWG=3517 kcal ME/kg) and contained 7.5 ppm ractopamine. One pig/pen was harvested on d 7 and 21, with remaining pigs harvested on d 35. For d 7-21 and 0-35 pigs fed the HL diets tended (<em>P</em><0.06) to have improved G:F compared to pigs fed LL diets. For d 21-28 (<em>P</em><0.03) and 0-35 (<em>P</em><0.03) pigs fed LL diets had greater ADFI than pigs fed HL diets. Pigs fed mannanase tended to have increased ADFI (<em>P<</em>0.06) d 21-28 and improved (<em>P<</em>0.10) ADG (984 vs 937 g/d) from d 21-35. Pigs fed the CWG diet had improved ADG (<em>P</em><0.04) from d 21-35 and 0-35 and for periods d 7-21 (<em>P</em><0.01) and 0-35 (<em>P</em><0.07) had reduced ADFI compared to pigs fed the HL diet. This resulted in improved G:F (<em>P<</em>0.01) from d 14-21, 21-28, 7-21, 21-35, and 0-35. Pigs harvested on d 7 fed mannanase diets had increased (<em>P<</em>0.01) carcass yield and tended to have increased (<em>P<</em> 0.06) loin depth, but reduced yield (<em>P<</em>0.06) on d 21. Pigs fed LL diets had increased (<em>P<</em>0.05) backfat (BF) depth compared to pigs fed HL diets on d 7. Pigs fed HL diets harvested on d 21 had reduced (<em>P<</em>0.01) BF depth and increased (<em>P<</em>0.03) percent lean versus pigs fed LL diets. Pigs fed CWG had increased (<em>P<</em>0.02) BF depth d 21 and d 35 and reduced (<em>P<</em>0.03) percent lean d 21 compared to pigs fed the HL diet. Overall, pigs fed HL diets had reduced (<em>P<</em>0.04) BF depth and tended to have increased (<em>P<</em>0.08) percent lean when compared to pigs fed LL and CWG diets. </p> <p>A second experiment was then designed to evaluate β-mannanase with and without β-glucanase in combination with ractopamine feeding. One-hundred eighty pigs (initial BW=105.4 ± 1.29 kg) were used to evaluate the effects of two enzymes individually and in combination in a corn-soybean meal-cDDGS based diet on pig growth performance and feed efficiency during late finishing. Pigs were allocated in a randomized complete block design of mixed gender pens, stratified by ancestry, gender, and initial BW to 5 treatments with 6 pens/treatment and 6 pigs/pen. Dietary treatments included: 1) negative control (0.75% SID Lys; NC); 2) NC plus ractopamine (RAC); 3) RAC+mannanase (0.08 MU/kg β-mannanase; RENZ1); 4) RAC+enzymes (0.08 MU/kg β-glucanase + 0.10 MU/kg β-mannanase; RENZ2); 5) RAC+enzymes (0.08 MU/kg β-glucanase, 0.18 MU/kg β-mannanase; RENZ1+2). Treatments 2-5 contained 5 ppm ractopamine from d 0-14 and 10 ppm ractopamine from d 14-28. For d 0-14, pigs fed the RAC diet had increased (<em>P</em><0.003) ADG, improved feed efficiency and tended (<em>P</em><0.06) to have increased ADFI when compared to pigs fed the NC diet. Pigs fed RENZ1 had increased (<em>P</em><0.05) ADG, and improved (<em>P</em><0.02) G:F, while pigs fed RENZ2 tended (<em>P</em><0.08) to have reduced G:F compared to pigs fed RAC. Pigs fed RAC from d 14-28 had increased (<em>P</em><0.05) ADG, ADFI, and improved G:F compared to NC. Feeding RENZ1, RENZ2, or RENZ1+2 had no impact (<em>P></em>0.22) on ADG, ADFI, or G:F from d 14-28 compared to RAC fed pigs. For the overall period d 0-28, pigs fed RAC diets had increased (<em>P</em><0.04) ADG and ADFI with improved (<em>P</em><0.001) feed efficiency compared to NC. Pigs fed RENZ1 had increased (<em>P</em><0.02) ADG and improved (<em>P</em><0.01) feed efficiency while pigs fed RENZ2 had no improvement (<em>P></em>0.21) in measured response criteria compared to pigs fed RAC. Pigs fed RAC had increased (<em>P<</em>0.01) final live BW, carcass weight, loin depth, fat free lean, and value per pig. In conclusion, pigs fed the RAC diet had increased ADG and ADFI with improved feed efficiency throughout the trial. Pigs fed RAC + mannanase had increased ADG resulting in improved feed efficiency compared to pigs fed RAC. </p> <p>Chapter 3 focused on one experiment split over two growth periods was conducted to evaluate the effect of saccharomyces cerevisiae or lactobacillus acidophilus fermentation products (SCFP and LAFP, respectively) and vaccination for <em>Mycoplasma hyopneumoniae</em> and Porcine circovirus type 2 on growth performance, serum immune markers, and intestinal villi height. In period 1, 135 pigs [Duroc × (Yorkshire × Chester); initially 5.75 ± 0.51 kg BW] were blocked by ancestry, sex, and initial BW (6 blocks) and assigned to mixed gender pens (4 or 5 pigs/pen) to 5 treatments with 6 pens/treatment. Treatments included: 1) Negative control (NC), control diets, non-vaccinated no added fermentation products; 2) Positive control (PC), control diets, vaccinated, no added fermentation products; 3) PC + SCFP (0.2% d 0-21, 0.1% d 21-56); 4) PC + LAFP (0.1% d 0-21, 0.05% d 21-56; LAFP-Low); 5) PC + LAFP (0.2% d 0-21, 0.1% d 21-56; LAFP-High). Diets were corn-soy based. Two gilts and one barrow per pen were repeatedly bled every 7 days from d 0-35. One of the identified bleeding gilts per pen was selected to be sacrificed on d 33 of the trial for intestinal tissue sample collection. For d 7-14 NC (<em>P<</em>0.05) pigs had improved G:F compared to all other vaccinated pigs. For d 14-21 (<em>P<</em>0.03), d 21-28 (<em>P<</em>0.05, d 28-35 (<em>P<</em>0.09), and d 0-35 (<em>P<</em>0.02) vaccinated pigs had increased ADFI and tended to have improved ADG (<em>P<</em>0.09) from d 14-21 compared to NC pigs. Similarly, from d 0-35 PC pigs tended (<em>P<</em>0.09) to have increased ADFI when compared to NC pigs. Villus height d 33 tended (<em>P<</em>0.07) to be reduced when pigs were vaccinated vs the NC. For d 35 all vaccinated pigs tended (<em>P<</em>0.10) to have increased TNF-α vs NC. On d 28 a larger percentage of LAFP-High pigs tested positive (<em>P<</em>0.01) for circovirus. On d 35 a higher percentage of NC pigs tested negative (<em>P<</em>0.001) for circovirus. During the nursery period mycoplasma optical density (MOD) was lower (<em>P<</em>0.05) for LAFP-Low and High than vaccinated PC while mycoplasma sample to positive (S/P) ratio tended (<em>P<</em>0.08) to be lower in LAFP-Low and High vs vaccinated PC. During the nursery period MOD and S/P ratio increased (<em>P<</em>0.001) more on d 14 than d 21, d 28, or d 35. During the nursery period circovirus titers were significantly increased (<em>P<</em>0.03) for all vaccinated pigs vs NC. Both LAFP-Low and LAFP-High pigs had increased (<em>P<</em>0.001) circovirus titer compared to PC and SCFP. During the nursery period circovirus titers were lower (<em>P<</em>0.05) on d 14 and d 28 vs d 21 and d 35. Circovirus titer results during the nursery period were reduced for NC (<em>P<</em>0.004) when compared to all other vaccinated groups. During the nursery period circovirus titer results were higher (<em>P<</em>0.001) on d 21 than d 14 & d 28, and higher (<em>P<</em>0.01) on d 35 than on d 21. </p> <p>In period 2 of the trial, 90 remaining pigs (initially 18.63 ± 1.50 kg BW) were combined by nursery treatment and assigned to mixed gender pens (6 pigs/pen) with 3 pens/treatment. During this grow-finish period, nursery treatments continued from d 35 to 56 post-weaning. After d 56 the control treatments continued, and the fermentation product treatments were fed SCFP: 3) SCFP (0.1% SCFP d 56-market); 4) LAFP-Low (0.1% SCFP d56-market); 5) LAFP-High (0.2% SCFP d 56-market). Diets were corn-soy based during this grow-finish period. From d 56-77 the main effect of vaccination tended (<em>P<</em>0.08) to increase ADFI while worsening G:F (<em>P<</em>0.06). As a result, overall (d35-market) ADFI tended (<em>P<</em>0.07) to be increased when pigs were vaccinated. During the grow-finish period MOD, mycoplasma S/P ratio, mycoplasma sample result, circovirus titer, and circovirus titer result all were reduced (<em>P<</em>0.0001) when pigs were not vaccinated. Similarly, the main effect of day had significant impact on all blood criteria measured throughout the grow-finish portion of the trial, however there were interactive effects for mycoplasma titer result (<em>P<</em>0.005) were non vaccinated pigs showed lower titer results from d 56 to 98 when compared to vaccinated pigs, then had 100% positives, the same as vaccinated pigs. Similarly, there was a treatmentxday interaction in the grow-finish period for circovirus titer, where non vaccinated pigs started negative and remained negative throughout the trial, while vaccinated pigs started with 100% having a titer then declined by day 119 and 140 to 50-75% positive.</p> <p><br></p> <p><br></p>

Crossbred pigs (n=144, avg age and weight - 28 ± 3 d, 7.5 kg) were used in two 6 wk trials to assess the effects of dietary pH and phosphorus source on performance, gastrointestinal digesta pH and chloride ion concentration (Cl⁻), bone characteristics and body composition. Pigs were blocked according to weight within sex and litters were balanced across groups. Treatments were randomly allotted within blocks to a 3 x 2 factorial arrangement with three dietary pH levels (5.4, 6.0 and 6.7) and two phosphorus sources: dicalcium phosphate (DCP) and defluorinated phosphate (DFP). Pigs fed the pH 6.7 diet had reduced average daily gain (ADG, P < .01) and average daily feed intake (ADFI, P < .001) during wk 1-3 and overall compared with pigs fed the pH 6.0 diet, but ADG and ADFI were not effected when the pH 5.4 diet was fed. There was a dietary pH by phosphorus source interaction (P < .05) for ADFI. DCP fed pigs had increased ADFI as dietary pH was reduced from 6.7 to 5.4, but DFP fed pigs had similar ADFI as dietary pH decreased from 6.0 to 5.4, and decreased ADFI as dietary pH increased from 6.0 to 6.7. Dietary pH had little influence on F:G, and phosphorus source had little effect on either ADG, ADFI or F:G. Dietary pH did not influence the pH and Cl⁻ of the digesta for any gastro-intestinal section measured, except the Cl⁻ in the stomach; both pH 5.4 and 6.7 fed pigs had a higher (P < .01) Cl⁻ than the pH 6.0 fed pigs. Only shear force of the fourth metacarpal and specific gravity of the fourth metatarsal were increased (P < .01) for pigs fed the DCP compared with DFP diets. Neither dietary pH nor phosphorus source influenced backfat or loin muscle area. These results suggest that maintaining the acidifity of the diet during the first 3 wk after weaning at 28 d of age is important with the primary response seen in ADFI. Varying dietary pH from 5.4 to 6.7 had little or no effect on gastrointestinal digesta characteristics, bone development and body composition. / Master of Science

Pigs can consume a wide range of feeds to meet their nutritional needs and there is a renewed interest in the use of cheaper nutrient resources for animal feeding. Forages have been proved to be a substantial source of nutrients for pigs, however, the bulk of the existing work has focused on sows and grower-finisher pigs above 50 kg. This study was conducted during May-June 2009 at the Agricultural Research Council (Irene, Pretoria) to determine the voluntary forage intake and nutrient digestibility in growing pigs fed a mixed diet (concentrate + Kikuyu grass). Twenty five 8 weeks old Large White x Landrace crossbred pigs (27 ± 3.8 kg) were blocked by weight into 5 groups of 5 pigs each. One of 5 treatments (A, B, C, D and E), corresponding to 100, 90, 80, 70 and 80 % of a basal concentrate ration, respectively, was randomly assigned to a pig within each block. Indoor treatments were either fed the concentrate only (A) or also received freshly cut Kikuyu grass (Pennissetum clandestinum) ad libitum (B, C and D). Only treatment E animals were housed outdoors in Kikuyu grass paddocks while all other treatments were housed indoors. Forage intake was recorded daily and also estimated using a pair of n-alkanes as markers. Nutrient and diet digestibility were calculated using acid-insoluble ash (AIA) and dotriacontane (C32) as markers. The results showed that the concentrate intake (CI) in treatments A, B and C was significantly different from treatments C and E (P < 0.05) and there was positive correlation between the concentrate level and its intake (P < 0.01). The recorded intake of Kikuyu grass (RKI) and the animal’s average daily gain (ADG) were similar between treatments (P > 0.05). The estimated (EKI) and recorded (RKI) Kikuyu grass intakes were not influenced by CI or the level of concentrate allowance (CL) and RKI was higher (P < 0.05) than EKI. Digestibility estimates with AIA were higher than C32 Keywords: Dotriacontane; Kikuyu; growth performance; forage; monogastrics estimates (P < 0.05). It was concluded that Kikuyu grass intake was not affected by the reduction of the concentrate level allowance. It was proposed that forage intake in a mixed diet (forage + concentrate) was more dependant on its own characteristics than the concentrate’s nutritional value. / Agriculture, Animal Health and Human Ecology / M. Sc. (Agriculture)

Pigs can consume a wide range of feeds to meet their nutritional needs and there is a renewed interest in the use of cheaper nutrient resources for animal feeding. Forages have been proved to be a substantial source of nutrients for pigs, however, the bulk of the existing work has focused on sows and grower-finisher pigs above 50 kg. This study was conducted during May-June 2009 at the Agricultural Research Council (Irene, Pretoria) to determine the voluntary forage intake and nutrient digestibility in growing pigs fed a mixed diet (concentrate + Kikuyu grass). Twenty five 8 weeks old Large White x Landrace crossbred pigs (27 ± 3.8 kg) were blocked by weight into 5 groups of 5 pigs each. One of 5 treatments (A, B, C, D and E), corresponding to 100, 90, 80, 70 and 80 % of a basal concentrate ration, respectively, was randomly assigned to a pig within each block. Indoor treatments were either fed the concentrate only (A) or also received freshly cut Kikuyu grass (Pennissetum clandestinum) ad libitum (B, C and D). Only treatment E animals were housed outdoors in Kikuyu grass paddocks while all other treatments were housed indoors. Forage intake was recorded daily and also estimated using a pair of n-alkanes as markers. Nutrient and diet digestibility were calculated using acid-insoluble ash (AIA) and dotriacontane (C32) as markers. The results showed that the concentrate intake (CI) in treatments A, B and C was significantly different from treatments C and E (P < 0.05) and there was positive correlation between the concentrate level and its intake (P < 0.01). The recorded intake of Kikuyu grass (RKI) and the animal’s average daily gain (ADG) were similar between treatments (P > 0.05). The estimated (EKI) and recorded (RKI) Kikuyu grass intakes were not influenced by CI or the level of concentrate allowance (CL) and RKI was higher (P < 0.05) than EKI. Digestibility estimates with AIA were higher than C32 Keywords: Dotriacontane; Kikuyu; growth performance; forage; monogastrics estimates (P < 0.05). It was concluded that Kikuyu grass intake was not affected by the reduction of the concentrate level allowance. It was proposed that forage intake in a mixed diet (forage + concentrate) was more dependant on its own characteristics than the concentrate’s nutritional value. / Agriculture, Animal Health and Human Ecology / M. Sc. (Agriculture)

Two trials were conducted in order to assess the efficacy of microbial phytase supplementation in improving the bioavailability of certain nutrients in the diet of early weaned piglets. In trial I, a low-phosphorus, corn-soybean meal diet supplemented with phytase significantly improved the apparent digestibilities of phosphorus (P, p = 0.0004) and calcium (Ca, p = 0.04). The average daily gain (ADG) and feed conversion ratio (FCR) were also improved by supplemental phytase. In trial II, addition of acetic acid to the low-P plus phytase diet further improved the apparent digestibilities of P and Ca (gp = 0.01, p = 0.02, respectively). Furthermore, the apparent digestibility of copper was also significantly improved by acetic acid addition. As a consequence, the piglets fed this treatment showed the best growth performance. Acidification of a diet which provided the NRC recommended levels of available P significantly improved the apparent digestibilities of protein and most of the minerals (P, Fe, Zn, Cu and Mn) but it was not reflected in improved growth performance. These results indicate that microbial phytase not only released P from the phytic acid molecule but it also cleaved other minerals bound to this complex.

A set of experiments were conducted to evaluate the antibody response, serum vitamin E level, cortisol concentration and performance of pigs weaned at three ages (21, 28 or 35 d) and fed diet containing either 11 or 220 IU/kg diet recommended level of vitamin E. Supplemental dietary vitamin E (220 IU) increased the concentration of serum vitamin E but, did not affect performance, cortisol concentrations or the antibody response. As weaning age increased, weekly performance increased linearly as did cortisol levels. Animals weaned at 35 d age had the largest primary antibody response, but this difference was not observed for the secondary response. A second set of experiments evaluated effects of four dietary vitamin E levels (11, 110, 220 and 550 IU/kg feed) on the humoral and cell-mediated immune response and performance of 4 wk old weanling pigs housed at one of two nursery temperatures (19 or 30°C). Performance was greater for pigs housed at 19°C compared with pigs housed at 30°C, but mitogen stimulation indices of white blood cells, plasma cortisol levels, and antibody titers were similar. Serum and liver vitamin E levels linearly increased with increasing dietary vitamin E level, but performance, cortisol, antibody levels and mitogen induced stimulation indexes were not affected by supplemental vitamin E levels. In the third experiment, sows fed a NRC level of vitamin E demonstrated little fluctuation in serum vitamin E concentration during a 5 wk lactation period. There was a high concentration of vitamin E in colostrum, followed by a sharp decrease in milk vitamin E concentration after the first week of lactation and remained constant for the next four weeks. Piglet serum was initially low in vitamin Eat 1 d of age but increased with time peaking about week 3. These experiments suggest that supplementing dietary vitamin E above the levels recommended by the NRC to baby pigs (which nursed sows fed NRC recommended levels of vitamin E) will not influence cell-mediated or humeral immune response, performance parameters or cortisol levels when pigs were weaned at various ages or exposed to environmental temperature changes. / Doctor of Philosophy

No description available.

Three experiments were conducted using crossbred weanling pigs (n=462) to determine the effect of yeast culture (YC) additions to starter diets containing dried whey or a fiber source on performance and nutrient digestibility. An 18% CP corn-soybean meal basal diet was used in all experiments. In Exp. I (n=192), YC (O or .75%) was used in diets with dried whey (0 or 15%) in two 5-wk trials (1 and 2). In Exp. II (n=174), YC (0 or .75%) was used in diets containing no added fiber, 8% soybean hulls (SH), or 8% peanut hulls (PH) in two 5-wk trials (3 and 4). Fifty-four of the pigs in Trial 4 were continued on test for three additional weeks in a grower phase. In Exp. II (n=96), YC (0 or .75%) was used in diets containing three levels of PH (0, 8, and 16%) in one 6-wk trial. In Exp. II, .05% chromic oxide was added to all six diets, and six grab samples were taken (twice daily every other day) during wk 4 and 6 for determination of the digestibility of DM, N, P, and fibrous components using the indirect method. Pigs in all experiments had ad libitum access to feed and water, and body weight and feed consumption were measured weekly. Results from all experiments showed that there was no overall effect of treatments on ADFI. In Exp. I, there was no significant overall effect of YC on ADG or G:F in either trial. In Trial 2 of Exp. I, whey depressed overall ADG (P < .10) and G:F (P < .005). In the nursery phases of Exp. I, there were no significant dietary treatment effects on ADG. Gain to feed ratios tended to be increased (P < .10) by YC additions, but only in diets which also contained fiber. In the grower phase of Trial 4 (Exp. II), fiber additions depressed ADG (P < .005), whereas YC additions improved ADG (P < .01), particularly in pigs fed diets which also contained SH (P < .05). In Exp. III, pigs fed diets containing YC and 8% PH had an overall ADG similar to controls, whereas pigs fed diets containing YC alone or both YC and 16% PH had a lower overall ADG than control pigs (P < .10). Overall G:F ratios were decreased by PH inclusion (P < .01) and by supplemental YC (P < .05). Apparent digestibilities were not influenced by the inclusion of YC. The addition of PH linearly decreased the digestibilities of DM (P < .001), N (P< .05), NDF (P < .001), and ADF (P < .05), and increased the absorption of P (P < .05). These results suggest that YC additions had no effect on ADG or ADFI, variable effects on G:F, and no effect on digestibilities of DM, N, NDF, or ADF, or the apparent absorption of P. Fiber additions, particularly PH at the 16% level, appear to depress ADG and G:F, and the digestibilities of DM, N, NDF, and ADF, but increase apparent absorption of phosphorus. / Master of Science

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.