The importance of a high feed intake during lactation of primiparous sows nursing large litters

The objective of this study was to investigate whether nursing a large number of piglets has negative effects on lactation and postweaning performance of primiparous sows and whether a greater lactation feed intake can prevent possible negative effects. Data were recorded on 268 ad libitum-fed sows of three genotypes (G1, G2, and G3) in an experiment where litter size was standardized to 8, 11, or 14 piglets during a 4-wk lactation. Compared to G1 and G2, G3 sows were heavier (P < 0.05) and leaner (P < 0.05) at weaning of their litters, lost similar amounts of BW and backfat, and their piglets grew faster (P < 0.05). Compared to G1, feed intake during lactation was higher for G3 sows (P < 0.05), and their risk of a prolonged weaning-to-estrus interval was lower (P < 0.01). Daily feed intake by sows was not affected by litter size in G1 and G3, but it was quadratically affected in G2 (P < 0.05), with a maximum at 10.8 piglets. Backfat loss of the sows increased linearly with litter size (P < 0.05) in G1 and G3. In G2, backfat loss increased only at litter sizes > 9.8 piglets (P < 0.01). Body weight loss of the sow and litter weight gain increased linearly with litter size (P < 0.001). Per extra piglet nursed, sows had a 23% (P < 0.01) higher probability of a prolonged weaning-to-estrus interval. A higher daily feed intake during lactation reduced tissue loss of the sow, increased litter weight gain (P < 0.01), and reduced the probability of a prolonged weaning-to-estrus interval (by 42% per extra kilogram; P < 0.01). Sows with a lower daily body weight loss during first lactation had a larger second litter (1.28 piglets/kg; P < 0.01), and their probability of a prolonged weaning-to-estrus interval was reduced by 61% per kilogram (P < 0.001). With increasing litter size, it is therefore recommended to reduce body weight loss during lactation by stimulating daily feed intake and by genetic selection.     

大豆对不同猪种有关器官形态的影响

将 1 5头长白仔公猪和 1 5头民猪仔公猪分别随机分成 5组 ,每组 3头 ,平均初始体重 ,长白仔猪 2 2 .9kg,民猪仔猪 2 2 .0 kg。试验仔猪单独饲养在水泥圈内。试验饲粮 5种 ,分别含有 2 0 %的阿根廷生大豆、阿根廷熟大豆、东北生大豆、东北熟大豆及不含大豆制品 (对照饲粮 )。每组仔猪饲喂试验饲粮 1种 ,日喂 3次 ,按料水比为 1∶ 1浸泡。预饲期 3d,试验期 1 4 d。试验结束时 ,将所有仔猪屠宰 ,立即对小肠、大肠采样 ,以备光镜和电镜观察 ,然后测定相关组织的重量和长度。结果表明 ,长白仔猪与民猪仔猪相比 ,小肠较重、较长 ,肾脏较重 ,但脾脏则较轻 ( P<0 .0 5)。饲喂含熟化处理的全脂大豆饲粮的仔猪 ,其胰脏比饲喂对照饲粮 ( P<0 .0 5)和含生全脂大豆饲粮的仔猪要轻 ,但在生、熟全脂大豆饲粮间差异不显著。小肠重在饲粮与猪种间存在显著互作 ( P<0 .0 5)。长白仔猪在饲喂含全脂大豆饲粮时 ,其小肠较重。在光镜和扫描电镜下观察 ,饲喂含东北生大豆饲粮的仔猪 ,其小肠上皮绒毛 (特别是长白仔猪 )遭到严重损害 ;在透射电镜下观察 ,这些猪的小肠上皮细胞微绒毛间存在气泡。组织学检查表明 ,饲喂对照饲粮的仔猪 ,其绒毛和腺窝中的杯状细胞的比例明显低于饲喂含生、熟全脂大豆饲粮的仔猪 (分别为 P<0 .0 1 ,P<     

Body composition in non-reproductive adult males and females in a long-term selection experiment for litter size in mice

Earlier studies have shown that adult mice from a line selected for high litter size (S-line), in particular females, had higher residual food intake (RFI) than mice from a non-selected control line (C-line). It was suggested that this increase in RFI, in particular the mature selected females, may anticipate the metabolically stressful periods of pregnancy and lactation. The present study investigated whether body composition at maturity has been changed as a correlated response to selection, in order to support the offspring during pregnancy and lactation. Furthermore, part of the observed differences between individuals in RFI may be attributable to differing proportions of body protein and lipid. For these reasons, differences in body composition at maturity between males and females of the S-line and the C-line were investigated. Lipid percentage was similar for C-line animals and S-line females; S-line males had a significantly lower lipid percentage. Males had a higher protein percentage than females, in particular S-line males. The results show that body composition in adult non-reproductive females has not been affected as a correlated effect of selection for high litter size. Furthermore, the results suggest that the high lean content in S-line males may explain part of the high RFI compared with C-line animals. Body composition in S-line females probably does not explain the high RFI compared with S-line males and C-line animals. Factors other than protein and lipid levels must be responsible for the differences found between the lines and sexes in RFI.     

Changes in oestrogen,progesterone and epidermal growth factor receptor concentrations and affinities during the oestrous cycle in the normal mammary gland and uterus of dogs

Changes in the concentrations and affinities of receptors for oestrogen (ER), progesterone (PR) and epidermal growth factor (EGF-R) were studied in mammary glands of healthy bitches with regard to age, the location in the mammary chain and the stage of the oestrous cycle. Uterus was used as the reference tissue for the evaluation of steroid receptors. Mammary and uterine samples from 7 healthy bitches were taken at five stages of the oestrous cycle in such a way that all the locations in the mammary chain were represented at each stage of the cycle (10 samples/dog). ER, PR and EGF-R were detected by biochemical assays using increasing concentrations of tritiated (steroids) or iodinated (EGF) ligands. A significant direct correlation was found between the ER and PR concentrations for mammary and uterine samples. No significant correlation was found between the steroid receptors and EGF-R concentrations. Mammary ER concentrations were significantly higher in bitches of 5 years of age or older than in younger ones; in posterior glands (4th and 5th pairs) than in anterior glands; and in the mid-luteal phase. Mammary PR did not vary significantly with age or location but was significantly lower in the early luteal phase than in other phases. A similar decrease in PR concentrations was observed in the uterus during the early luteal phase and uterine ER and PR concentrations were very low in the mid-luteal phase. Mammary EGF-R were not significantly higher in the early or mid-luteal phase than in pro-oestrus or anoestrus.The differences observed between the uterine and mammary steroid receptor concentrations during the oestrous cycle could be due to different mechanisms for regulating steroid receptor expression in the two tissues. Mammary EGF-R concentrations may be linked, as in other species, to cellular proliferation and/or to the serum progesterone concentrations.Abbreviations BSA bovine serum albumin - EGF epidermal growth factor - EGF-R receptor for epidermal growth factor - ER oestrogen receptor - K _d dissociation constant - LH luteinizing hormone - p probability of error - PR progesterone receptor     

Difference in energy metabolism and protein retention of limit-fed growing pigs of several breeds

Energy metabolism and protein retention of four pig breeds were studied in three experiments comparing Norwegian (N) landrace with either Finnish (F) landrace (Exp. 1), Great Yorkshire (Y, Exp. 2) or Dutch landrace (D, Exp. 3). An increasing or decreasing temperature regimen (11 to 26 degrees C) was used. The animals were kept at a constant feeding level (about 93 g.kg -.75.d -1). Energy and protein balances were measured at increasing and decreasing temperature conditions separately. The three landrace breeds utilized their dietary energy and protein with similar efficiencies. However, large differences were observed between Y and N pigs in Exp.2. The Y pigs had a higher growth rate, lower feed/gain, lower heat production, and higher protein deposition than the N pigs. These differences were related to a lower level of activity of the Y pigs. This lower activity level resulted in lower maintenance requirements of the Y pigs compared with the N pigs. Growth rate and feed conversion differed between balance periods. When the temperature within a period was being increased, growth rate was higher and feed/gain was lower compared with periods in which the temperature was being decreased. Breeds differ with respect to energy and protein utilization.     

Alteration of energy metabolism of calves fed below maintenance during 6 to 14 days of age.

A study was conducted with seven groups of five to six Holstein-Friesian male calves to evaluate the effect of feeding level during 6 to 14 d of age on energy metabolism of unadapted young calves. Calves were transported at 2 to 3 d of age to their new environment. At 6 d of age measurements of heat production (HP) and ME intake started and continued over a period of 8 d. Calves were fed below (four groups) or near (three groups) the maintenance requirement (19 or 30 g of milk replacer powder.kg-.75.d-1). In contrast to ME intake, HP decreased throughout the experimental period. This decrease was larger at the low than at the high feeding level (3.1 vs .9 kcal.kg-.75.d-2; P less than .001). The relationship between HP and ME intake was estimated as HP = 91 + .318 x ME intake (kilocalories.kilogram-.75.day-1). The decrease in HP, together with the constant ME intake with time, resulted in a time-dependent relationship between HP and ME intake. Estimated basal metabolic rate and efficiency of ME utilization below maintenance decreased with time, whereas the maintenance requirement remained virtually unchanged (134 kcal.kg-.75.d-1). The influence of feeding level on energy metabolism in young calves increased with time. For at least 12 d after transportation the energy metabolism of young calves had not reached steady-state levels.     

Metabolism of bromhexine in pig hepatocyte cultures

The metabolism of bromhexine [N-cyclohexyl-N-methyl-2-(2-amino-3,5-di-bromo-benzyl)-amine] was studied using pig hepatocyte cultures and LC/MS/MS techniques. Phase I 'single-step' reactions, i.e. hydroxylation and demethylation occurred the fastest whereas the formation of hydroxylated/demethylated and aminal hydroxylated metabolites, which can be considered as multiple-step reactions, occurred more slowly. Phase II conjugates were detected for all hydroxylated metabolites. The glucuronides of the hydroxylated/demethylated components tended to accumulate. In addition to metabolites known to be formed in vivo, three unknown components related to bromhexine were detected. Two of these metabolites accumulated during incubation. Based on the fragmentation patterns, a possible molecular structure is proposed for these components.     

Rapid chilling cannot prevent inferior pork quality caused by high preslaughter stress

The present experiment investigated whether increasing chilling rate could improve meat quality in pigs exposed to either minimal or high stress immediately preslaughter. Pigs (n = 192) were offspring of halothane-free lines. On various days, four groups of 48 pigs were processed at a commercial plant. Within each group, half the pigs were exposed to either minimal or high preslaughter stress. Before entering the cooler at 45 min postmortem, carcasses of both minimal and high preslaughter stress treatments were allocated randomly to either conventional (+4 degrees C for 22 h) or rapid (three-phase chilling tunnel: -15, -10, and -1 degrees C for 15, 38, and 38 min, respectively, followed by storage at 4 degrees C until 22 h postmortem) chilling. Temperature and pH were measured in the blood at exsanguination and in the longissimus lumborum (LL) and semimembranosus (SM) muscle at 0.5, 2.5, 4.5, 6.5, and 22 h postmortem. Meat quality attributes (water-holding capacity and objective color measurements) were assessed on the LL. Preslaughter stress level affected pH and temperature in both blood and muscle, with lower (P < 0.001) pH values and higher (P < 0.001) temperatures for pigs exposed to high vs. minimal stress. Rapid chilling led to a faster (P < 0.001) temperature decline regardless of preslaughter stress level. Rapid chilling did not (P > 0.05) influence the rate of pH decline in the LL muscle, but reduced (P = 0.061) pH decline in the SM. Rapid chilling, as opposed to conventional chilling, decreased (P < 0.05) electrical conductivity in the LL, regardless of preslaughter stress; however, it could not compensate for the detrimental effect (P < 0.05) of stress on drip loss, filter paper moisture absorption, and meat color (L* value). Results from the present study indicated that increasing chilling rate is not a suitable method to resolve pork quality problems caused by inadequate preslaughter handling.