Pork quality is an important issue for the whole meat chain, from producers, abattoirs, retailers through to costumers and is affected by a web of multi-factorial actions that occur throughout the pork production chain. A vast amount of information is available on how these diverse factors influence different pork quality traits. However, results derived from individual studies often vary and are in some cases even contradictory due to different experimental designs or different pork quality assessment techniques or protocols. Also, individual influencing factors are often studied in isolation, ignoring interacting effects. A suitable method is therefore required to account for a range of interacting factors, to combine the results from different experiments and to derive generic response-laws. The aim of this thesis was to use meta-analyses to produce quantitative, predictive models that describe how diverse factors affect pork quality over a range of experimental conditions.

No description available.

This study investigated the water use of lactating sows (experiment 1), suckling piglets (experiment 2), weaned piglets (experiments 3, 6 and 8) and growing pigs (experiments 4, 5, 7 and 9), according to 3 specific objectives which assessed the effects of: age, live weight, feed intake and physiological status on water demand (experiments 1 to 3); different types of drinker on water use (experiments 4 to 6); dietary mineral content on water demand (experiments 7 and 8). For all classes of pig, feed intake explained between 53 and 83% of the variation in water use (P < 0.001). The relationship between stage of lactation and live weight (experiments 3, 6 and 7) was confounded by feed intake. In sows water use increased linearly in the week before farrowing (P < 0.001) which then decreased from 12.3 ± 1.10 1 the day before, to 9.3 ± 0.84 1 the day of farrowing (P < 0.001). Water use averaged 18.9 ± 0.27 1/day in a 21 day lactation. With suckling piglets, provision of water and/or creep feed between days 8 and 21 did not influence growth ( P > 0.05). Provision of creep feed reduced water use (0.22 ± 0.019 v 0.53 ± 0.035 1/litter day; P < 0.001), but water provision did not influence feed intake (34.7 ± 3.4 g/litter day; P > 0.05). Early weaned piglets (21 d) showed a disturbed pattern of water use in week 1 and water use averaged 0.94 ± 0.050 1/piglet day between weeks 1 and 3. In growing pigs, water use per unit of feed intake decreased linearly from 17 to 81 kg W and water use averaged 5 ± 0.16 1/day. Type of drinker influenced performance immediately after weaning (P < 0.001), but results with growing pigs were less conclusive. Water use from the Mono-flo nipple drinker was about twice that from 5 other types of drinker (P < 0.001). Dietary potassium (K) increased the water use of growing pigs by 1 1/day for every 1% increase in K between 7 and 15 g/kg feed (P < 0.05) , but performance was not affected (P > 0.05). With piglets water use and performance were not affected by variations in dietary K and Cl contents between 6.7 and 15.6; 1.4 and 3.0 g/kg feed respectively (P > 0.05). Growing pigs fed liquid diets utilised a supplementary water supply even though the water added to the meal exceeded ARC (1981) recommended allowances (experiment 9). Daily weight gain and conversion of dry matter improved as the moisture content of the liquid diets was increased from 67 to 88% (P < 0.05).

Summer and winter experiments were carried out to investigate the effects of dietary supplementation with vitamin E and vitamin C of sows in hot environments on reproductive performance, placenta transfer, piglet tissue vitamin E content and some indicators of immune status of sows and their litters. In summer, sows were given the following treatment diets: control, vitamin C 1g/day, vitamin C 10g/day, vitamin E 200 mg/kg feed, vitamin E 400 mg/kg fed, and combined vitamins (vitamin E 200 mg/kg feed + vitamin C 1 g/day). In winter, sows were given the following treatment diets: control, vitamin C 10g/day, vitamin E 500 mg/kg feed, combined vitamins (vitamin E 500 mg/kg/feed + vitamin C 10g/day). Data show that vitamin E had an effect on growth, but not on reproductive performance. Placental vitamin E concentrations were low but increased with dietary vitamin E supplementation. Vitamin E supplementation resulted in an increase in vitamin E content of sow plasma, piglet serum, colostrum and milk and piglet tissues. Supplementation with vitamin E and vitamin C had no consistent effect on parvovirus titer in sows. The relationship between sow plasma vitamin C and vitamin E concentrations and lymphocyte proliferation was not clear. Total Igs and IgG concentrations in piglet serum at weaning were significantly increased by the combined vitamin treatments. However, vitamins supplementation did not appear to have any effect in IgG colostrum. IgA concentration in milk was increased by the high level of vitamin E supplemented in the summer but not in the winter experiment.

Work was undertaken to determine the efficiency of growing lambs offered a fixed amount of roughage and concentrate as; 1) a mixed diet (M), containing 500 g/kg DM roughage and 500 g/kg DM concentrate, 2) split feeds (S), roughage alone followed by concentrate alone, 3) a mixture changing from roughage to concentrate (R-C), or concentrate to roughage (C-R), or 4) half the animals offered roughage and half concentrate (R/C). Lamb growth was predicted from computer models based on current feeding standards. In experiment (1), lambs were offered 50 kg roughage DM and 50 kg concentrate DM by strategies M and S. Lambs on strategy S took longer to consume their food and maintained a higher EBW ^0.75 than those on strategy M. However, the final EBW and EB composition of the two groups was similar. This contrasted with predicted results. The higher overall efficiency of lambs on strategy S was explained partly by associative effects reducing the energy available to lambs on strategy M, and partly by a higher efficiency of energy utilisation and/or a lower maintainance requirement of lambs on strategy S. In experiment (2), the influence of associative effects on strategies R-C and C-R was investigated. The prediction of dry matter digestibility (DMD, Y) from concentrate proportion (CONCP, X1) and dry matter intake (X2) showed no curvilinearity. DMD was linearly related to CONCP. The equations derived for each strategy were similar. In experiment (3), lambs were offered 52.5 kg roughage DM and 52.5 kg concentrate DM by strategies M, R-C, C-R and R/C. Lambs on strategies R-C, C-R and R/C took a similar time to consume their food and achieved a similar final EBW and EB composition. Their energy retention (ER) was similar to that predicted. Lambs on strategy M consumed their food faster than those on all other strategies and achieved a higher (NS) EBW, which contained more (NS) fat. Their ER was higher than predicted. The higher overall efficiency of lambs on strategy M was explained by differences in the ratio of protein: fat deposited and maintained by lambs on each strategy. The EB composition of all slaughtered lambs was within the limits for published data. Non-carcass composition could be used to predict EB composition. The results highlight the importance of the factors mentioned in determining the efficiency of lambs on each strategy.

Rice bran arises as a by-product from rice milling industry. The anti-nutritional substances such as phytate, non-starch polysaccharides, protease inhibitor and lectin limit the nutritional value of this by-product. This research was directed toward the nutritional improvement of defatted rice bran (DRB) using feed enzymes to degrade these anti-nutritional factors. Three growth experiments and two tube feeding experiments were carried out to investigate the effect of phytase, carbohydrase and protease enzymes (supplied by Finnfeeds International) on broiler performance, mineral retention, nutrient digestibility, digesta viscosity and bone characteristics of chicken fed defatted rice bran based broiler diets. Enzyme supplementation of diets was conducted to assess the effects of individual and a cocktail of enzymes and/or lactobacillus culture. The data showed that inclusion of DRB at more than 150 g/kg without additional inorganic phosphate reduced feed intake, growth, bone mineralisation and produced the symptoms of rickets in broiler chickens. Experimental phytase successfully released phosphorus from DRB which counteracted the symptoms of a phosphorus deficient rickets-producing diet and improved feed intake, growth and bone mineralisation. Data presented in this study indicate that inclusion of DRB in broiler diets did not produce viscous digesta in the gut and carbohydrase supplementation did not improve bird performance, nutrient digestibility and mineral retention. The digesta viscosity was not decreased by carbohydrase; therefore, the non-starch polysaccharide (NSP) content of DRB did not play an important role in production of viscous digesta. Supplementation of DRB based broiler diets with protease improved dry matter (DM) and protein digestibility and P retention; therefore, the improvement in feed conversion ratio (FCR) was a result of better utilisation of nutrients. The data showed that there is a potential to decrease the phytate and lectin content of DRB broiler based diets by supplementing diets with phytase and protease.

No description available.

A programme of study was undertaken to assess the effect of pretreating raw soya bean and processed full fat soyabean meals with protease enzymes prior to use in liquid feed for grower and finisher pigs. A series of laboratory studies was undertaken to examine the efficacy of three microbial proteases (P2, P3 and P4) in partially hydrolysing soya protein and in reducing the levels of trypsin inhibitors in raw soyabean. Pretreatment consisted of steeping ground soyabean for 24 h at 20° C in the absence (control) or presence of 20 000 units gˉ¹ N of P2, P3 or P4. Pretreating raw soyabean (RSB) with P2, P3 and P4 significantly (P < 0.05) reduced trypsin inhibitor levels from 28.53 to 19.98, 17.17 and 18.35 (s.e.m.1.14) mg trypsin inhibited gˉ¹ soya respectively. Pretreating RSB, micronized (MIC) or autoclaved (AUT) soyabean meal with P2, P3 or P4 resulted in increases in soluble a.-amino nitrogen of 5.22, 7.08, and 6.58 (RSB), 5.11, 5.57 and 4.32 (MIC) and 3.56, 7.03 and 6.18 (s.e.d. 0.06) mg gˉ¹ soya respectively and in vitro digestibility of nitrogen of 7.6 %, 9.9 %and 6.4 % (RSB), 4.9 %, 8.3 % and 2.8 % (MIC) and 11 %, 8 % and 12.2 % (AUT) respectively compared with the appropriate controls. Feeding trials were conducted in which pretreated soya was added to a basal cereal diet. Pretreatment of RSB with P4 resulted in a significant (P < 0.05) increase in ADG of 0.08 kg pigˉ¹ dˉ¹ (s.e.d. 0.04) in grower pigs (33.5 ± 4 kg) over the 6 week duration of the trial but had no significant effect on FCR. Pretreatment of AUT with P4 did not significantly improve performance. In a feeding trial with grower/finisher pigs pretreatment of RSB with P3 resulted in significant (P < 0.05) improvements of 0.10 (s.e.d. 0.04) kg pigˉ¹ dˉ¹ in ADG and 0.476 (s.e.d. 0.19) in FCR. Pretreatment of MIC with P3 resulted in a significant reduction (P < 0.05) of 4 d (s.e.d. 1. 7) in the time taken for pigs to attain slaughter weight.

No description available.

No description available.