1982 experiments were conducted to examine several aspects of forage quality in relation to animal nutrition, including the differences in quality between forage types (legumes or grasses), species and varieties; between years; between two hay mixes; and between three harvest dates. In addition, the importance of quality relative to yield is examined. In the first experiment, acid detergent fibre, neutral detergent fibre, crude protein, and nylon bag dry matter disappearance determinations were used to assess the variation in quality between forage types, species and varieties, and between years. In the second, voluntary dry matter intake and digestibility results were used to assess the variation in quality between hay mixes and harvest dates. The results of the first experiment indicate that the legumes were of higher quality than the grasses; red and alsike clover were of higher quality than alfalfa, and orchardgrass was of higher quality than timothy. With the exception of red clovers, where Lakeland and Pacific varieties were of higher quality than Altaswede, there was little difference in quality between varieties within a species. Neutral detergent fibre analysis results suggest a difference in intake between forages grown in different years while acid detergent fibre analysis results indicate no difference in digestibility would be expected between years. The results of the second experiment indicate there was a difference in quality between forage mixtures (the early maturing mixture was best), and harvests (early and mid bloom harvests were better than the late bloom harvest). The parameter with the largest variability was yield. Differences were greater between years than between types and species (the clovers highest, alfalfa and timothy intermediate, and orchardgrass lowest) with the least variation occurring between varieties within species. The red clover-timothy (late maturing) forage mixture was the highest yielding. Within forage mixtures the full bloom harvest (100% bloom of the legume component) had the highest yields. Since yield was more variable than the quality parameters studied, it was concluded that the most important consideration when selecting a forage mixture was yield. Since there tended to be little difference in quality parameters between varieties within a species, selecting the highest yielding combination would provide the largest amount of useable nutrients per hectare of land base. / Land and Food Systems, Faculty of / Graduate

The biological activity or availability or feedstuff selenium was determined by comparing the effectiveness of the feedstuff with that of dietary sodium selenite in preventing the incidence of exudative diathesis in the chick. The available selenium in ten wheat samples varied from 62 to 178 percent with a mean of 105 percent. The selenium availability in rapeseed meal ranged from 27 to 89 percent with a mean of 61 percent. Selenium metabolism in the chick was investigated by adding graded levels of sodium selenite to the basal selenium deficient diet and comparing the dietary selenium concentration to the selenium concentration in the tissues (l.e. Blood, liver, kidney, and muscle of the chicks). The selenium content in the tissues examined increased proportionately to an increase in dietary selenium supplementation from 0 to 0.2 ppm. Blood and liver selenium concentration remain relatively constant (a slightly increasing plateau) from 0.2 to 1.0 ppm of dietary selenium. Above 1.0 ppm dietary selenium, blood and liver selenium levels increase steadily. These results show that either blood or liver selenium levels represent the selenium status of the bird. A similar response in tissue selenium levels of the chick was observed when selenium was supplied either as sodium selenite Or a feedstuff (brewers yeast). Furthermore, selenium levels birds fed wheat diets were similar to those fed equivalent selenium (sodium selenite) supplied in the basal diet. / Land and Food Systems, Faculty of / Graduate

Please read the abstract in the section 00front of this document. / Dissertation (MSc (Agric) Animal Nutrition)--University of Pretoria, 2006. / Animal and Wildlife Sciences / unrestricted

<p>Porcine reproductive and respiratory syndrome virus (PRRSV) is estimated to cost the US swine industry $664 million in annual production losses. Therefore, the objective of this project was to evaluate the effect of MCFA on PRRSV replication using in vitro and in-vivo studies. The overarching hypothesis was that MCFA would inhibit or reduce viral replication of PRRSV infection in vitro and reduce viral load in-vivo. In the first experiment (Chapter 2), MARC-145 cells were used to determine the effects of individual MCFA (C6, C8, C10, and C12) exposure at concentrations ranging from 1-1000 µg/mL prior to and following inoculation of North American Type II (P-129) or European Type I (Lelystad) PRRSV. Viral replication was determined using FITC labeled IgG anti-PRRSV monoclonal antibody and TCID₅₀was calculated for each concentration. Data were analyzed using the Proc Mixed procedure of SAS. Incubation of MARC-145 cells with caproic acid (C6) at concentrations of 1-1000 µg/mL prior to and after inoculation with Type II North American (P129) or Type I European (Lelystad) PRRSV did not alter viral replication (<i>P</i> > 0.10). However, incubation of MARC-145 cells with caprylic (C8), capric (C10), and lauric (C12) acid prior to and after inoculation with Type I and Type II PRRSV did reduce viral replication at concentrations ranging from 100-1000 µg/mL. In general, the effective dose required to reduce (<i>P </i>< 0.05) viral replication (Log₁₀TCID₅₀/mL)decreased as MCFA chain length increased. In experiment 2 (Chapter 3), the use of MCFA combinations (C8:C10; C8:C12; C10:C12; and C8:C10:C12) to reduce viral replication of PRRSV in MARC-145 cells was investigated. The MCFA combinations were analyzed at six different concentrations ranging from 50-500 µg/mL with North American Type II (P-129) and European Type I (Lelystad) PRRSV. Viral replication was determined as described in experiment 1 (Chapter 2) using FITC labeled IgG anti-PRRSV monoclonal antibody and Log₁₀TCID₅₀/mL was calculated for each concentration. Data were analyzed using the Proc Mixed procedure of SAS. Incubation of MARC-145 cells with MCFA combinations prior to and after inoculation with Type II North American (P129) and Type I European (Lelystad) PRRSV resulted in reduced viral replication at MCFA concentrations of 200-500 µg/mL and was concentration dependent. Reduction of viral replication with MCFA was further evaluated by independently incubating MARC-145 cells or PRRSV. Results indicated that viral replication was reduced when MARC-145 cells were incubated with MCFA and not when PRRSV was incubated with MCFA. In experiment 3 (Chapter 4), 112 mixed sex pigs (PIC 1050 females x PIC 359 sire), weaned at 21 d of age, weighing 7.5 ± 0.68 kg, were used in a 33d PRRSV challenge study. Pigs were blocked by body weight and sex and randomly assigned to one of four treatments in a 2x2 factorial design with pigs receiving 0 or 0.30% MCFA in the diet and placebo or PRRSV inoculation. Following a 5 d adjustment to diets and rooms, pigs were inoculated with either a placebo (sterile PBS) or Type II North American (P129) PRRSV (1 x 10⁵,TCID₅₀/mL) given in 1 mL each intranasal and IM injection. Each room contained 4 pens with 7 pigs per pen and an equal ratio of barrows to gilts within treatment. Diets were formulated to meet or exceed all nutritional requirements (NRC, 2012) and were fed in 4 nursery phases. Feed budgets by phase were 1.13 kg/pig in phase 1, 2.72 kg/pig in phase 2, 6.35 kg/pig in phase 3, and phase 4 fed until the end of the experiment. MCFA (C8:C12) were mixed in a 1:1 ratio (wt:wt), and then mixed with finely ground corn to prepare a premix added to diets at 0.60% to provide 0.30% total MCFA. Control diets used soybean oil mixed with finely ground corn at the same 0.60% inclusion to keep ME levels constant across treatments. Body weights, feed intakes, blood samples, and temperatures were determined or collected on d 0, 3, 7, 10, 14, 21, and 28 post inoculation. Sections of tonsil, lung, and intestines were collected at d 10 post-inoculation from 1 pig per pen and at d 28 from all remaining pigs. Data were analyzed using the PROC Mixed procedure of SAS with pen as the experimental unit for growth and performance measurements and pig as the experimental unit for viral load analysis. Serum viral load confirmed PRRSV was only detectable in challenged pigs. Body weights were not different (<i>P</i> > 0.05) between treatments prior to d 14 post inoculation. Body weights from d 14 to 28 post inoculation were reduced (<i>P</i> < 0.05) in PRRSV infected pigs compared to non-infected pigs. Overall ADG and ADFI were reduced (<i>P </i>< 0.05) for PRRSV infected pigs compared to non-infected pigs by an average of 18 and 28%, respectively. Body temperatures were not different between treatments. Viral load measured in the lung was not different (<i>P </i>> 0.05) between PRRSV infected treatments. Tonsil viral load was not different (<i>P</i> > 0.10) between PRRSV treatments. However, there was a trend (<i>P</i> ≤ 0.10) for an effect of day post inoculation with control-fed, PRRSV-infected pigs having higher viral loads at d 10 post inoculation compared to d 28 post inoculation. Overall, no effects of MCFA on PRRSV viral load or performance were observed during the in-vivo trial. MCFA was effective at reducing viral replication of PRRSV in MARC-145 cells in vitro. However, the results could not be confirmed in the in-vivo experiment. Porcine alveolar macrophages should be used to confirm the in vitro inhibition of PRRSV replication observed in MARC-145 cells. In order to fully understand the application of MCFA to inhibit PRRSV infection in pigs, more studies should be conducted to evaluate the form of MCFA as well as viral inoculation with field strains of PRRSV. </p>

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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>

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