Effect of surgical castration,immunocastration and chicory-diet on the meat quality and palatability of boars

This study evaluates 1) carcass quality, meat quality and palatability for barrows, immunocastrates and boars and 2) the effect of chicory supplemented feed during 10 days before slaughter on boar meat quality.     

Effect of preslaughter fasting on the characteristics of pig livers

Seventy-seven pigs of about 60 kg liveweight were killed in two experiments, which examined the influence of food deprivation preslaughter on the chemical composition, physical characteristics and eating quality of liver. In the first experiment pigs were fasted for 0, 24 or 48 hr before slaughter. Livers from fasted animals were lighter in weight ( P < 0.001) and contained proportionally slightly more water ( P < 0.001), fat ( P < 0.001) and protein ( P < 0.001) but very much less glycogen ( P < 0.001) and less lactate ( P < 0.001). They had higher pH values ( P < 0.001) both just after slaughter and during storage at 2°C for up to 72 hr. They were darker in colour initially ( P < 0.05) and after chilling for 72 hr ( P < 0.01) partly due to the higher ( P < 0.05) concentrations of haem pigments. The second experiment examined how these differences influenced eating quality. It included a control group killed 2 hr after food withdrawal and groups fasted for 12, 24 and 48 hr. After frying, livers from pigs fasted longer were found to be darker in appearance ( P < 0.001), less tender ( P < 0.001), less juicy ( P < 0.001) and, overall, less acceptable ( P < 0.001). Livers from pigs fasted longer also lost less weight during cooking ( P < 0.05) and were tougher ( P < 0.05) based on instrumental measurements. Livers from half of the pigs in each fasting group were stored at 2°C prior to assessment of eating quality; the remaining livers were frozen at −20°C. Freezing had small deleterious effects on the texture ( P < 0.01) and juiciness ( P < 0.05) of livers but did not influence mean overall acceptability.     

The composition and consistency of pig backfat as it affects the quality of vacuum-packed rindless bacon rashers

Samples of adipose tissue from unsatisfactory, soft, vacuum-packs of rindless bacon rashers were compared with satisfactory harder samples to determine the factors responsible for the difference in consistency. Lipid from unsatisfactory packs contained significantly higher mean concentrations of unsaturated fatty acids, lower mean concentrations of saturated fatty acids and had a lower mean melting point and mean slip point. Discriminant analysis revealed that the samples were best differentiated according to their proportion of linoleic acid or by the ratio of stearic acid to linoleic acid. Linoleic acid was the best discriminator although stearic acid and palmitic acid were correlated best with the melting point and slip point of the lipid and with the force required to puncture the intact adipose tissue by a probe attached to an Instron materials testing machine. Samples which would give satisfactory firm packs, based on the data from discriminant analysis, required a puncture force greater than 7N. In terms of the spectrum of backfat consistency in British pigs, satisfactory bacon comes from hard backfat whereas the unsatisfactory packs come from backfat of medium consistency.     

半胱胺和酵母铬对生长猪饲粮养分消化代谢的影响

采用全收粪(尿)法,进行消化代谢试验,研究生长猪饲粮中分别或同时添加半胱胺和酵母铬对饲粮养分的消化利用率影响。结果表明:生长猪饲粮中分别或同时添加半胱胺和酵母铬在一定程度上改善了饲粮干物质、无氮浸出物、粗蛋白质、总能、粗脂肪、粗纤维、钙和总磷等养分的表观消化吸收率,提高了氮的沉积率和表观生物学价值(P>0.05);酵母铬和半胱胺二者具有一定的协同作用。     

高粱原花青素对生长育肥猪抗氧化、免疫以及养分消化率的影响

研究高粱原花青素(sorghum procyanidins,SPC)对生长育肥猪生长性能、养分消化率、消化酶活性、免疫力和抗氧化能力的影响。160头70日龄、平均体重为(31. 28±1. 12) kg的杜×长×大三元杂交猪,按照单因素完全随机设计分为4个组,分别饲喂玉米-豆粕基础日粮,以及基础日粮中添加100、150、200 mg/kg SPC。实验期为14周,生长期和育肥期各7周。在每个实验阶段开始和结束时称重,每天记录采食量,计算各阶段平均日增重(ADG)、平均日采食量(ADFI)和料重比(F/G)。在每个实验阶段的最后3 d,收集粪样测养分消化率。在每个实验阶段结束时,采血测血清抗氧化指数和免疫参数,同时,每个重复随机屠宰2头猪,取胰腺组织,测消化酶活性。结果表明,日粮添加SPC对生长育肥猪的生长性能没有显著的促进作用(P 0. 05)。在生长猪阶段,日粮添加150 mg/kg和200 mg/kg SPC显著降低了消化酶的活性,对养分消化率有降低的趋势。在育肥猪阶段,日粮添加150 mg/kg显著提高了粗蛋白的表观消化率(P 0. 05),200 mg/kg SPC显著地抑制了消化酶的活性(P 0. 05)。与对照组相比,不论是在生长期还是育肥期,添加150 mg/kg或200 mg/kg的SPC均显著地增强了猪血清谷胱甘肽过氧化物酶(GSH-Px)和超氧化物歧化酶(SOD)的活性以及血清总抗氧化能力(T-AOC)(P 0. 05),降低了血清丙二醛(MDA)浓度(P 0. 05),提高了猪血清IgG、IgM和白细胞介素2(IL-2)的浓度(P 0. 05)。总之,SPC有利于提高生长育肥猪抗氧化能力,增强免疫力,但是对于生长育肥猪的生长性能及养分消化率没有显著的促进作用,相反,高浓度的SPC甚至抑制了消化酶的活性,从而影响养分的消化利用。     

The effect of expander processing and pelleting on the nutritive value of feed for growing and finishing pigs

Two experiments were conducted to determine the effect of pelleting and/or expander processing on the nutritive value of feed when fed to growing and finishing pigs. Experiment 1 determined the effects of pelleting and/or expander processing on the apparent nutrient digestibility of the diets. In experiment 2, productive performance and carcass characteristics were determined in group‐fed pigs (n = 312) offered identical diets in raw pellet form (T1), expander‐processed pellet form (T2), raw meal form (T3) and expander‐processed meal form (T4). The expanded diets were expander processed at 105 °C for 5 s at 35 bar pressure. The pellet diets were steam pelleted at 85 °C into 3.0 mm pellets. Pelleting of the diets increased organic matter (P < 0.05), protein (P < 0.01), energy (P < 0.01) and ash (P < 0.01) digestibility as well as the digestible energy (DE) content of the diets (P < 0.01). Expander processing had no effect on the organic matter, protein and energy digestibility of the diets. There was a significant interaction (P < 0.05) between pelleting of the diet and expander processing in DE content of the diets. Expansion had no effect on the DE content of the pelleted diets; however, expansion increased the DE content of the meal diets (P < 0.05). In experiment 2 there was a significant interaction between the physical form of the diet and expansion in feed intake during the grower and finisher period (P < 0.01). Expander processing had no effect on feed intake in the pelleted diets; however, expansion decreased feed intake of the meal diets (P < 0.001). Both pelleting and expansion of the diets decreased growth rate during the grower and finisher period (P < 0.05). Pelleting of the diets improved feed conversion ratio (FCR) during the grower and finisher period (P < 0.05), while expander processing had no effect on FCR. © 2000 Society of Chemical Industry     

Breakdown of plant carbohydrates in the digestive tract of pigs fed on wheat‐ or oat‐based rolls

Cell wall materials from various cellular tissues of cereals may potentially influence the digestion and absorption processes in different ways. The objective of the present investigation was to study the breakdown of plant carbohydrates in the gastrointestinal tract of pigs fed a low‐fibre (LF; 65 g kg⁻¹ dry matter) wheat flour‐based diet and two high‐fibre diets with added insoluble fibre from wheat bran (HFWB; 112 g kg⁻¹ dry matter) or soluble fibre from oat bran (HFOB; 108 g kg⁻¹ dry matter). The diets were formulated to provide ∼0.31 energy from fat, ∼0.18 energy from protein and ∼0.51 energy from carbohydrates and were offered as baked rolls to eight ileum‐cannulated hypercholesterolemic pigs in a crossover design. Carbohydrates were the predominant ileal constituent, with most of the carbohydrates present as non‐starch polysaccharides (NSP). Starch in all diets was almost completely digested at this site of the gastrointestinal tract, with digestibility values above 0.99. The ingested amount of NSP was quantitatively recovered in ileal materials with the wheat‐based diets, while there was a significant loss of 0.27 of NSP primarily as mixed linked (1→3)(1→4)‐‐D ‐glucan with diet HFOB. The concentration and flow of lactic acid were also highest in the ileum after feeding diet HFOB, indicating that ‐glucan stimulated lactic acid formation. Any soluble components that reached the large intestine were almost completely broken down, while the digestibility of insoluble NSP constituents was significantly lower for diets LF and HFWB than for diet HFOB. The high degradation of oat bran resulted in a lower effect on faecal dry and wet bulking than was found with wheat bran. In conclusion, cereal starch was practically completely degraded in the small intestine, while the site and extent of NSP degradation, lactic acid formation and bulking properties were influenced by the fibre source. © 2000 Society of Chemical Industry     

Supplementary α‐tocopherol acetate in full‐fat rapeseed‐based diets for pigs: effect on performance,plasma enzymes and meat drip loss

Twenty‐four Large White × Landrace pigs were individually fed, from 50 to 90 kg live weight, either a control (CONT) diet containing palm oil or one of three diets based on full‐fat rapeseed (250 g kg⁻¹) (diets RD). The RD diets were supplemented with 0, 200 or 500 mg DL ‐α‐tocopherol acetate (ATA) kg⁻¹ diet (diets RD0, RD200 and RD500 respectively). Diets were formulated to be isonitrogenous and isocaloric. Daily live weight gain was significantly increased (p < 0.01) in pigs fed diet RD500. Plasma AT concentration was significantly increased by dietary supplementation with 200 mg ATA kg⁻¹ but showed no further significant increase by supplementation with 500 mg ATA kg⁻¹. At slaughter, after 45 days, carcass weights were increased for the RD500 group but dressing percentage was unaffected. ATA supplementation significantly reduced drip loss on days 4 and 5–7 in fresh muscle and on days 1 and 4 in frozen muscle. The concentrations of calcium, sodium and potassium in drip loss fluid collected on days 1 and 4 from fresh muscle were not significantly affected by treatment or by time of collection and did not suggest any change in the relative contribution of intra‐ and extracellular fluid to total drip loss. Plasma enzyme activities related to tissue damage (creatine kinase, alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase) were not influenced by dietary treatments. © 2000 Society of Chemical Industry     

Integration of ileum cannulated pigs and in vitro fermentation to quantify the effect of diet composition on the amount of short‐chain fatty acids available from fermentation in the large intestine

Using cannulated pigs and a standardised in vitro fermentation system the effect of diet and non‐starch polysaccharides (NSP) on the amount of energy available from microbial fermentation in the large intestine could be predicted. The available energy was calculated from the amounts of short‐chain fatty acids (SCFA) produced. Three diets were investigated: a low fibre diet based essentially on wheat flour (56 g NSP kg⁻¹ feed) and two high fibre diets with added oat bran (93 g NSP kg⁻¹ feed) or wheat bran (102 g NSP kg⁻¹ feed). Colonic fermentation was estimated by in vitro fermentation of freeze‐dried ileal effluent collected from cannulated pigs. The in vitro fermentation method was optimised to use 10 g ileum content litre⁻¹ incubated at pH 6.0 in a fermentor containing faecal slurry consisting of anaerobic mineral salts medium and 50 g litre ⁻¹ faeces from pigs fed the same diets as the cannulated pigs. The results demonstrate that it is very important to compensate for the faecal SCFA contribution when calculating the amount of SCFA produced from ileal digesta during in vitro fermentation. The amount of NSP digested in vitro was compared with data obtained from in vivo studies and there was a good agreement between in vivo and in vitro data. We concluded that the integrated in vivo–in vitro method is a valuable technique to estimate the effect of diet and NSP on the amount of SCFA produced in the large intestine and when fed the three diets the microbial fermentation in the large intestine provided between 2.4–6.4% of the total available energy. © 1999 Society of Chemical Industry