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The relationship between porcine growth hormone (pGH) and insulin-like growth factor-I (IGF-I) in swine was investigated. IGF-I levels were measured by radioimmunoassay (RIA) with an antisera specific for human IGF-I after ultrafiltration of acidified samples. Ultrafiltration quantitatively separated carrier proteins and IGF-I. Failure to separate these species interfered with the RIA. Using this assay, swine chronically treated with pGH had 2.6-fold higher sera levels of IGF-I than controls, whereas, serum IGF-I from a hypophysectomized animal was only 4% that of normal animals. The ultrafiltration procedure was incorporated into a protocol to measure IGF-I in sera from neonatal swine treated with pGH (5O ug •kg BWt⁻¹•d⁻¹). Treatment of neonatal pigs with pGH for one or two weeks elevated pGH in sera, but did not significantly affect either growth or serum IGF-I concentrations. Preliminary studies were performed to determine if neonatal swine hepatocytes secreted IGF-I in vitro. Results indicated that neonatal hepatocytes synthesized limited quantities of IGF-I that approached the detection limits of the RIA. Furthermore, pGH did not stimulate hepatocyte IGF-I synthesis in vitro or in vivo. Neonatal hepatocytes synthesized a protein species that bound labeled IGF-I and had a molecular weight similar to a carrier protein in swine serum. Estimation of the rate of carrier protein synthesis suggested that IGF-I and carrier proteins are coordinately regulated in isolated neonatal hepatocytes. These results suggest that IGF-I is not inducible in the neonatal pig by GH therapy and that growth in neonatal swine is either maximal or GR-independent. / M.S.

The purpose of this study was to investigate the effect of intrauterine position and its possibly resultant steroid differential on conceptus growth and steroid content in allantoic and amniotic fluid of pigs. six conceptus variables (placental weight, placental length, fetal weight, fetal length, allantoic fluid volume and amniotic fluid volume) and seven steroids (progesterone, androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate, testosterone, estrone and estrone sulfate) were evaluated. Four fetal positions were studied: females between females (f2F), females between males (fOF) , males between females (m2F) and males between males (mOF). Fetuses examined from ovariectomized (OVX) pregnenolone (PS)-treated gilts showed differences in placental weight, allantoic fluid estrone and androstenedione content and amniotic fluid androstenedione content as a result of intrauterine position. Fetuses from OVX gilts treated with either medroxyprogesterone acetate (MPA) I or progesterone (P4) showed differences in placental length due to intrauterine position. Allantoic and amniotic fluid content of any of the steroids studied from OVX MPA- and P4-treated gilts was not altered as a result of intrauterine position. Intrauterine position appears to have a definite influence on conceptus development and possibly on steroid content. However, discrepancies' of results among trials possibly as a result of differences in type and amount of exogenous precursor enable us to draw stronger conclusions on the intrauterine position effect. / Master of Science

The impact of within-litter weight variation on the productivity of pig enterprises is poorly understood. The objective of the study was to determine the effect of within-litter birth weight variation on litter performance at three weeks of age and at weaning. The study was conducted using records from 1 788 litters, collected between January 1998 and September 2010, from a pig herd at the Agricultural Research Council (ARC), Irene. The records consisted of piglet identity, breed of sow, breed of boar, parity number, date of farrowing, number of piglets born alive (NBA), individual piglet weight at birth, three weeks and at weaning. From these records, mean birth weight (MBWT), litter weight at birth (TBWT), within-litter birth weight coefficient of variation (CVB), minimum birth weight (MinB) and maximum birth weight (MaxB) were calculated. Mean weight at three weeks (MWTT), litter weight at three weeks (LWTT), within-litter weight coefficient of variation at three weeks (CVT), percent survival to three weeks (SURVT), mean litter weaning weight (MWWT), litter weight at weaning (LWWT), within-litter weaning weight coefficient of variation (CVW) and percent survival at weaning (SURVW) were computed as derivatives. The factors affecting CVB were analysed using the General Linear Model procedures (SAS, 2008). For the relationships between CVB and litter performance at three weeks and weaning, PROC STEPWISE was used. The PROC REG (SAS, 2008) was then used to test whether the relationships between CVB and CVT, SURVT, MWTT, LWTT, CVW, SURVW, MWWT, LWWT and LWWT. Multiparous sows farrowed litters with higher (P<0.05) CVB than gilts. The litter weight (TBWT) and NBA, fitted as covariates, also affected (P<0.05) CVB. The correlation between CVB and NBA was 0.30. The CVB had a linear relationship (P<0.05) with SURVT (SURVT = 83.21 - 0.20 CVB), CVT (CVT = 16.71 + 0.50 CVB), SURV (SURW = 87.9 – 0.04CVB) and CVW (CVW= 15.8 + 0.5CVB). An increase of CVT with CVB depended on parity (P<0.05). The rate of increase of CVT with CVB was highest in Parity 1 (b=0.41) followed by Parity 2 (b=0.36) then middle aged (Parity 3-5) sows (b=0.32). The CVB had no effect on MWTT, LWTT, MWWT and LWWT (P>0.05). The CVB was shown to be an important determinant of SURVT and SURVW. A uniform litter at birth is likely to lead to a homogenous litter at three weeks and weaning, thereby reducing costs of production. Pig producers should, therefore aim at producing homogenous litters at birth. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

The present studies were conducted to gain a better understanding of the effects of pregnenolone (P₅), human chorionic gonadotropin (hCG) and 3' 5', cyclic adenosine monophosphate ( cAMP) on porcine placental and endometrial production of progesterone (P₄), testosterone (T) and estrone (E₁) at 30, 60 and 90 days of gestation. Duplicate 300 mg samples of placenta, endometrium or both (co-incubation) were incubated in medium199 containing either no P₅, P₅, P₅ + hCG or P₅ + cAMP for either zero (control), .5, 1 or 2 h. The first study compared P₄ and E₁ production with or without addition of P₅. At d 30, 60 and 90, respectively, P₄ production (ng/g) increased significantly in the presence (vs absence) of P₅ in the incubation medium of placental (13.2 vs 7.5, 73.9 vs 42.7, 137.4 vs 113.5, respectively) coincubation (14.5 vs 10.0, 33.6 vs 22.3, 77.9 vs 49.4, respectively) and endometrial (16.0 vs 13.3, 23.0 vs 16.0, 17.1 vs 6.7, respectively) tissue. Presence of P₅ increased E₁ production in d 60 (1.3 vs .7 ng/g) and d 90 (51.7 vs 34.6 ng/g) placental tissue and d 90 endometrial tissue (9.8 vs 8.0 ng/g). In a second study, P₅ + cAMP increased (vs P₅ alone) P₄ in placental tissue at d 30 (11.6 vs 8.7 ng/g) and coincubation tissue at d 90 (103.7 vs 75.3 ng/g). Cyclic AMP stimulated increased P₄ synthesis ( vs P₅ alone), throughout the incubation period in d 60 and d 90 tissue. E₁ production by endometrial tissue at d 30 (4.1 vs 2.9 ng/g), and placental tissue at d 60 ( 1. 2 vs . 9 ng/g). Presence of hCG in the incubation medium had no overall effect on either P₄ or E₁ accumulation. Only trace amounts of T were detected in either study, suggesting rapid aromatization of C₁₉ steroids to estrogens. / M.S.

Three balance experiments were conducted to determine the effects of dietary fiber on mineral balance and intestinal.morphology of growing pigs. Fiber sources were added to corn-soybean meal diets at levels which increased neutral-detergent fiber levels by 6 to 8%. In experiment 1, 10% oat hulls (OH) decreased Ca (P<.06) and Zn (P<.01) balances of pigs after a 7 d feeding period. Wheat bran (20%) increased Mg intake and balance (P<.02), but did not affect Ca and Zn balances. In experiment 2, pigs were fed diets (with or without supplements of Zn, Fe and Mg) containing 15% OH or soybean hulls (SH) for 5 d or 26 d. SH increased Fe intake and balance (P<.01) and ( Mg absorption (P<.01). Compared with balances at 5 d, Zn balance was similar, while Fe and Mg balances were higher at 26 d for pigs fed the basal (P<.05) or SH (P<.01) diets. However, Zn balance was lower (P<.05) at 26 d 1 but Fe balance did not change over time for pigs fed the OH diets. At each time period, Zn balance was not different between pigs fed the basal or high-fiber diets. In experiment 3, Ca, Zn and Mg absorption were not affected by 15% OH or SH or 20% alfalfa meal (AM) after 67 d or 39 d, although SH and AM increased Fe balance (P<.01). Intestinal surface morphology of 12 pigs fed in experiment 3 was examined by scanning electron microscopy. Villus morphology was variable in jejunum, ileum and colon, although evidence of villus blunting and folding accompanied by erosion of microvilli and loss of epithelial cells was observed in small intestine of some pigs fed the SH and AM diets. Damage was not consistent in all sites examined in individual pigs, and did not occur in all pigs fed any specific diets. Although Ca and Zn balances were decreased by OH in two of the balance trials, the inability of OH to consistently decrease mineral balance suggests that the ability of the pig to adapt to different diets may be sufficient to overcome the mild inhibitory effect on mineral absorption of some fiber sources. When viewed together, the results of the balance trials indicate that moderate amounts of dietary fiber have a minimal negative impact on mineral balance of pigs fed practical corn-soybean meal diets. However, the results also indicate that fiber sources such as SH and AM, are rich sources of some minerals for the pig, particularly Fe. Evidence of intestinal damage was evident in pigs fed the high-fiber diets. However, not all animals fed a particular diet were affected, which suggests that some pigs within a given population may be susceptible to detrimental effects of dietary fiber on intestinal structure or function. / Ph. D.

Methods were developed to isolate and culture the predominant cell types from porcine liver to investigate hepatic accumulation, distribution and intracellular metabolism of supplemental iron. Hepatocytes were prepared from collagenase perfused livers by differential centrifugation, while Kupffer cells and endothelial cells were isolated by centrifugal elutriation. One day old piglets were injected with iron-dextran (Fe-dextran) and the concentration of accumulated iron was determined in all three cell types 1, 5, and 10 days later. The concentration of iron increased markedly in all three cell types when compared to cells isolated from untreated piglets (Kupffer cells > endothelial cells >> hepatocytes). Accumulated iron was subsequently mobilized from all three cell types. The role of ferritin in metabolism and storage of accumulated iron was investigated. An antiserum was prepared against porcine liver ferritin and the quantity of cellular ferritin was measured by immunoelectrophoresis. The amount of cellular iron associated with ferritin was assessed by ion exchange chromatography. All three types of liver cells accumulated ferritin in response to Fe-dextran treatment. Higher concentrations of ferritin-iron and ferritin-protein were present in Kupffer and endothelial cells than in hepatocytes at all times after iron treatment. However, at 1 day after treatment 48% of the total iron within hepatocytes was associated with ferritin; ferritin-iron accounted for only 10% of total cell iron by day 10. In contrast, ferritin-iron represented only approximately 9% of the total iron in sinusoidal cells throughout the study period. The possibility that accumulation of Fe-dextran enhanced peroxidation of membrane lipids was evaluated. Lipids extracted from heart and liver of iron-treated piglets contained increased levels of conjugated dienes. High levels of conjugated dienes were present in endothelial cells and hepatocytes 1 day after treatment and only in endothelial cells by day 5. Although Kupffer cells accumulated substantial quantities of Fe-dextran, conjugated dienes were not detectable. These studies indicate that treatment of piglets with Fe-dextran may selectively impair function of hepatic endothelial cells and perhaps hepatocytes, and define new criteria for evaluating compounds that are used for iron supplementation. / Ph. D. / incomplete_metadata

Physicochemical properties of fibre-based diets were used to determine the influence of feed bulk on physicochemical properties of digesta within each segment of the gastrointestinal tract and digesta in pigs. In the first experiment, three pigs (14 ± 1.2 kg body weight (BW) were allocated to each of six diets containing maize cob levels at 0, 80, 160, 240, 320 and 400 g/kg DM inclusion levels for four weeks. All pigs were fed ad libitum. They were slaughtered, eviscerated and weights of the gut compartments were recorded, then contents of digesta from each segment were sampled for the determination of water concentration, water holding capacity (WHC) and swelling capacity (SWC). The WHC of digesta in the stomach, ileum and caecum decreased (P < 0.05) with maize cob inclusion level. The SWC in the stomach decreased with the inclusion level of maize cob meal. The SWC of caecal digesta increased with maize cob inclusion (P < 0.05). Physicochemical properties of digesta increased (P < 0.05) from the stomach to ileum then decreased as the digesta moved through the hindgut. In the second experiment, four fibres namely maize cob, lucerne hay, sunflower husk and citrus pulp were used. These fibres were used in formulating diets for finishing pigs. Twenty-one complete diets were formulated by dilution of a conventional feed with increment levels of each fibre source at 0, 80, 160, 240, 320 and 400 g/kg. Each of the diets was offered ad libitum to four of 84 pigs weighing 80.8 ± 8.15 kg body weight, in individual pens, for 30 days. Stomach weights increased linearly with an increase in neutral detergent fibre (NDF) but increased with quadratic functions with an increase in SWC of the diet (P <0.05). An increase in WHC of the fibrous diets increased linearly the WHC of the proximal colon (P <0.01) at a faster rate compared to the WHC of the distal colon (P <0.001). As the SWC of the diets increased, linear increases in SWC of the digesta in the stomach (P <0.01) and caecum (P <0.001) were observed. The WHC of the digesta was negatively correlated to SWC (P < 0.001) in the stomach. Scaled feed intake (SFI) decreased linearly with an increase in SWC of the diet (P < 0.001). There was no relationship between WHC of the diet and SFI (P > 0.05). There was a linear decrease (P < 0.01) in SFI of finishing pigs as the SWC of the digesta. It can be concluded that the swelling capacity of the diets and stomach digesta in stomach are accurate predictors of scaled feed intake. Swelling capacity had great influence in the stomach weights whilst other bulking properties, such as WHC and neutral detergent fibre, affected the weight and digesta properties in the caecum, proximal and distal colon. / M.Sc.Agric. University of KwaZulu-Natal, Pietermaritzburg 2013.

This study was conducted to determine the influence of factors on the efficiency of protein utilization and the rate of lipid deposition and withdrawal in growing pigs. Two experiments were conducted in total. The first experiment involved fifty-two crossbred entire Large White x Landrace male pigs, individually penned, which were used to test the proposition that the efficiency of protein utilisation is influenced by the body composition of the pig at the start of the trial. The experiment was divided into two phases: in the first period, starting at 20kg liveweight, when 3 pigs were slaughtered to determine the initial body composition of the pigs on the trial, the remaining 48 pigs were divided into three groups, two of which were fed ad libitum, with 11 pigs being offered a feed high in crude protein (HP, 1979 CP/kg) and 19 pigs being offered a low CP (LP, 166g/kg) feed. The remaining 19 pigs were fed HP on a restricted basis; the daily allowance being 0.7 of the mean intake of those pigs fed HP ad libitum. The objective of this initial period was to create three groups of pigs differing in body lipid content. As each pig achieved a protein weight of approximately 5.9kg, predicted to occur when the pigs on the three treatments reached live weights of 35, 39 and 34kg respectively, the pig entered phase 2 of the trial. At this stage three pigs from each treatment (a total of 9 pigs) were slaughtered for carcass analysis, the protein contents being approximately 5.9kg, and lipid contents being 85,98 and 87g/kg for the 3 treatments respectively. During phase 2, the 8 pigs fed HP in phase 1 continued to be fed HP in phase 2; 8 pigs were chosen at random from those fed LP in phase 1 and were allocated the high CP basal feed, while the remaining 8 were given LP; and 8 of the pigs feed-restricted in phase 1 were randomly chosen and fed HP, while the remaining 8 were given LP. All pigs were fed ad libitum during phase 2. Four pigs from each treatment in phase 2 were slaughtered after 1 week and the remaining 4 a week later for analysis of body composition In the first week of the second phase of the trial protein gain was highest (264g/d) on the pigs previously restricted and then fed HP, followed by those previously fed LP and then HP (242g/d), with pigs previously restricted and then fed LP depositing the least amount of protein (192g/d). Pigs fed LP or HP throughout, had protein gains of 217 and 210g/d, respectively. Efficiencies of utilization of dietary protein did not differ significantly between treatments, however, the highest being measured in pigs fed LP throughout (461g/kg), followed in order by those fed LP and then HP (457g/kg), those fed HP throughout (404g/kg), those previously restricted and then fed LP (394g/kg), with those previously restricted and then fed HP being the least efficient (372g/kg). The second experiment involved twenty-six male and twenty-six female crossbred Large White x Landrace pigs, individually penned, which were used to determine the maximum rate at which growing pigs can gain lipid. The experiment was divided into three phases: In the first, starting at 20kg live weight (56 days old), when two males and 2 females were slaughtered to determine the initial body composition of the pigs on the trial, the remaining 24 males and 24 females were randomly allocated to their various treatments. The treatments consisted of a feed high in crude protein (H, 197g/kg), a feed low in CP (L, 166g/kg) and three blends, namely 5OH/5OL (180g/kg) (male diet), 30H/70L (167g/kg) (both male and female diets) and 20H/80L (162g/kg) (female diet). Six pigs from each sex were allocated to each treatment. The EFG Pig Growth Model was used to determine the fat contents (lipid index) on the two feeds available and the three blends, to estimate the best times to sample pigs. It was estimated that phase 1 would terminate at 63 d, phase 2 at 70 d and phase 3 at 77 d of age. At the end of each phase two pigs from each sex and treatment were slaughtered. The lipid contents differed significantly between treatments at the end of phase 2 for the male pigs, with the highest being measured in pigs fed L (108g/kg), followed in order by those fed 70L/30H (86g/kg), those fed 5OL/5OH (74g/kg), and those fed H (68g/kg) with the least lipid content. The lipid contents of the female pigs were highly significantly different at the end of phase 3, with the highest being measured in pigs fed L (147g/kg), followed in order by those fed 80L/20H (124g/kg), those fed 70L/3OH (116g/kg) and the least lipid content from those fed H (115g/kg). As estimated by the EFG Pig Growth Model, the male and female pigs fed L treatment had the highest lipid content and those fed H treatment, achieving their target rate of lipid deposition, with the lowest lipid content. This study indicates that the response in protein gain and in efficiency of utilization of protein of pigs to a given feed is dependent on the amount and quality of the feed given to the animals previously. Also, the maximum rate of lipid deposition can be achieved by monitoring the changes in lipid deposition over a period of time, which enables an enhanced understanding of the theory of food intake regulation in a growing pig. As a result, accurate changes can be made when designing a phase-feeding program for growing pigs. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

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.