Archives of Animal Nutrition最新文献

The objective of this study was to investigate the effect of variation in wheat-derived phytase activity on myo-inositol 1,2,3,4,5,6-hexakis (dihydrogen phosphate) (InsP₆) degradation, inositol phosphate (InsP) isomer concentration and phosphorus (P) digestibility in pigs fed wheat-based diets. Additional effects of a microbial phytase supplementation were also studied. Three wheat genotypes (W1-W3) with an analysed phytase activity between 2760 and 3700 FTU/kg were used to formulate four experimental diets that included soybean meal and rapeseed meal but did not contain a mineral P supplement. DietW1-DietW3 only differed in the included wheat genotypes (W1-W3) at an inclusion level of 400 g/kg. DietW3+ contained W3 and a commercial 6-phytase supplementation at 500 FTU/kg diet. Eight barrows with an initial body weight of 27 kg were fitted with a simple T-cannula at the distal ileum and assigned to the four dietary treatments in a completely randomised row column design. The experiment included four periods of 12 d each. The first 5 d of each period were for diet adaptation, followed by collection of faeces (4 d), ileal digesta (2 d), and blood (last day). In DietW1-DietW3, the mean precaecal (pc) InsP₆ disappearance was 48% and the mean pc P digestibility was 37% without a significant effect of the wheat genotype. The InsP₆ disappearance measured in the faeces was close to complete in all treatments, and faecal P digestibility was not significantly affected by the wheat genotype (36% overall). The addition of microbial phytase caused a significant increase in pc InsP₆ degradation (to 79%) and pc and total tract P digestibility (to 53% and 52%, respectively). The concentration of InsP₆ degradation products in ileal digesta was not significantly affected by the wheat genotype, except for that of Ins(1,2,3,4,6)P₅ and myo-inositol, which were higher in DietW3 than in DietW1 and DietW2. The added microbial phytase significantly reduced the concentration of InsP₅ isomers in the ileal digesta and increased the concentrations of lower InsP isomers and myo-inositol. There were no significant effects of the added microbial phytase on pc amino acid digestibility; however, the wheat genotype exerted significant effects on the pc digestibility of Cys, Gly and Val. It was concluded that an increase in the intrinsic phytase activity of wheat achieved by crossbreeding was not reflected in InsP₆ degradation and P digestibility in pigs fed wheat-based diets.

Thirteen pea grain samples from different origins were used to examine the variation in in situ ruminal degradation of crude protein (CP) and starch as well as in vitro gas production (GP) kinetics. In vitro GP was used to estimate the digestibility of organic matter (dOM), metabolisable energy (ME) and utilisable CP at the duodenum (uCP). Protein fractions were also determined according to the Cornell Net Carbohydrate and Protein System. Degradation of CP and starch from all pea grains in the rumen was almost complete, with a high proportion of the instantly disappearing fraction. The variation in the degradation constants among pea grain variants was high, and degradation of CP and starch showed a significant initial lag phase in the rumen. The mean effective degradation (ED) calculated for a rumen outflow of k = 8%/h of CP (EDCP8) was higher than ED of starch (EDST8), averaging 77.0 and 71.5%, respectively, with low variation among variants. A correlation analysis between GP parameters and in situ degradation constants showed no clear relationship, but the rates of in vitro GP and in situ starch degradation were similar. Most of the protein in the pea grains was buffer-soluble with fast and intermediate degradation. Variation in the protein fractions among the pea grain variants was low and not suitable for predicting differences in in situ degradation characteristics. The mean in vitro uCP of pea grains was 198 g/kg dry matter (k = 8%/h) and variation was low and consistent with that of GP kinetics and in situ rumen undegradable crude protein values. The estimation of dOM and ME from 24 h GP led to very high values indicating that the existing prediction equations may not be suitable for pea grains as a single feed.

Zinc (Zn), an important microelement in ruminant diet, plays a critical role in various enzymes, hormones and functional proteins involved in nutrient metabolism. The present study was conducted to assess the effect of zinc hydroxychloride (Zn₅(OH)₈Cl₂·H₂O [ZnOHCl] and zinc sulphate (ZnSO₄) on nutrient utilisation, mineral metabolism and biomarkers pertaining to growth performance in pre-ruminant crossbred calves. Twenty-four crossbred calves [body weight (BW); 31.03 ± 4.30 kg; age 10 d] were randomly allocated to four treatment groups (n = 6), i.e. no supplementation of Zn (0 mg/kg dry matter [DM]), 80 mg/kg DM Zn as ZnSO₄(ZnS-80), 40 mg/kg DM Zn as ZnOHCl (ZnH-40) and 80 mg/kg DM Zn as ZnOHCl (ZnH-80) for 90 d experimental period. Results showed that dietary Zn supplementation improved (p < 0.05) feed intake, BW, average daily gain, heart girth, body length, plasma growth hormone, insulin-like growth factor and thyroxin concentration; however, nutrient digestibility remained unaffected among the groups. Addition of Zn increased (p < 0.05) Zn retention and plasma Zn concentration without affecting  retention and plasma concentration of other minerals. Retention of Zn was the highest in ZnH-80 group followed by ZnH-40, ZnS-80 and lowest in control group. Overall results of the present study indicate that regardless of sources and levels, Zn supplementation increased growth performance, plasma Zn concentration and hormones levels in pre-ruminant crossbred calves. However, supplementation of hydroxy Zn at 40 mg/kg DM had similar effect as produced by ZnSO₄ or ZnOHCl at a supplementation level of 80 mg/kg DM. Therefore, from the present study it can be concluded that ZnOHCl can be used as a Zn source for pre-ruminant calves at a lower dose compared to ZnSO₄.

The feeding of high-concentrate diets commonly results in lowered pH and ruminal dysbiosis which cause shifts in uptake dynamics of short-chain fatty acids (SCFA) and altered epithelial function. Therefore, the current study evaluated the effect of dietary polyunsaturated fatty acids (PUFA) on ruminal fermentation products, gene expression in the ruminal epithelium and the associated changes in ruminal microorganisms in lambs fed a high-concentrate diet. Twenty-six Afshari lambs adapted to a high-concentrate diet during a completely randomised design were fed with a basal diet supplemented with 100 g oil supplement (OS; 60 g sunflower oil and 40 g fish oil) for 10 (OS10), 20 (OS20) and 30 (OS30) d, respectively (n = 6). Lambs with no oil supplementation (OS0, n = 8) were considered as control and slaughtered at d 0 of the experiment, and the remaining lambs were slaughtered at 10, 20 and 30 d on feed. After slaughter, ruminal digesta was collected for evaluating fermentation and microbial community. Ruminal papillae were taken for assessment of epithelial gene expression. Compared with OS0 lambs, supplemental PUFA in OS30 lambs tended to decrease total SCFA concentration with decreased acetic and increased propionic acid concentrations. Acetate:propionate ratios were decreased and ruminal pH was increased in OS20 and OS30 lambs compared to OS0. All groups with included OS had decreased concentrations of iso-valeric and valeric acids compared to OS0. Relative mRNA abundance of monocarboxylate transporter isoforms 1 and 4, insulin-like growth factor binding protein 3, sterol regulatory element-binding proteins 1 and 2 decreased with increasing OS duration. The relative abundance of 3-hydroxy-3-methylglutaryl-CoA synthase 1 mRNA transcript was higher for OS10 and OS20 lambs relative to OS0 lambs. OS20 and OS30 showed a decrease of lipopolysaccharide binding protein mRNA expression compared with OS0. Feeding supplemental PUFA decreased Ciliate protozoa and increased Butyrivibrio fibrisolvens in OS20 and OS30 lambs, whereas Megasphaera elsdenii was increased in OS30 lambs. In conclusion, combined supplementation of sunflower and fish oil to a high-concentrate diet affects the ruminal microbial community with prominent decreases in ruminal ciliate protozoa and increases in B. fibrisolvens and M. elsdenii. These results lead to a more stabilised ruminal pH and a fermentation shift towards more propionate generation. Consideration of nutrients digestion will help to fully understand the benefits of feeding PUFA with a high-concentrate diet.