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31.
1前言历史上,人们一直把水看成是充裕而廉价的资源,所以缺乏确定猪需水量或对影响水利用情况因素进行研究(Fraser等,1990)的积极性。现在,人类社会正越来越意识到水是有限的资源,而家畜生产行业却又是一个主 相似文献
32.
Effect of nutrient intake in lactation on sow performance: determining the threonine requirement of the high-producing lactating sow 总被引：2，自引：0，他引：2
Reproductive performance is steadily increasing within the pork industry; logically, amino acid requirements need to be redefined for sows producing larger litters. The objective of this study was to determine the threonine requirement of the high-producing lactating sow and to determine the effect of lysine on this requirement. A total of 419 PIC C-15 sows were assigned randomly to treatment within parity groups (1, 2, and 3+) and gestation treatment at d 110 of gestation. Lactation diets were formulated to contain 0.80% total lysine (tLYS) with 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, or 0.65% total threonine (tTHR) or 1.06% tLYS with 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, or 0.70% tTHR. Litters were standardized to a minimum of 11 piglets within 48 h after farrowing, and sows had free access to feed throughout lactation (lactation length = 20.1 +/- 0.1 d). Sow ADFI exceeded expectation, averaging 6.90, 7.40, and 7.20 kg/d for Parities 1, 2, and 3+, respectively. Daily tLYS intake was 58 g/d (47 g of apparent ileal digestible lysine [dLYS] per day) and 74 g/d (59 g dLYS/d) for the low- and high-lysine group, respectively. Lysine intake did not affect sow or litter performance (P > 0.10). Sows gained an average of 4.8 kg in lactation. Using regression analysis, BW gain was maximized at 0.54% tTHR for all parity groups (quadratic; P < 0.05). Litter weaning weight (67.1, 67.9, and 66.2 kg for Parities 1, 2, and 3+, respectively) and litter weight gain (2.49, 2.53, and 2.44 kg/d for Parities 1, 2, and 3+, respectively) were maximized at 0.53% tTHR using regression analysis, for all parity groups (quadratic; P < 0.05). Based on regression analysis, plasma urea nitrogen on d 10 and 18 was minimized at 0.54% tTHR (P < 0.05). Lysine levels in excess of 58 g of tLYS/d did not benefit sow or litter performance. The requirement for threonine to minimize sow tissue mobilization was 37, 40, and 38 g tTHR/d (28, 30, and 30 g of apparent ileal digestible threonine [dTHR] per day) for Parities 1, 2, and 3+ sows, respectively. The threonine required to maximize litter performance was 36, 39, and 38 g of tTHR/d (28, 30, and 29 g of dTHR/d) for Parities 1, 2, and 3+ sows, respectively. Alternatively, the requirement can be expressed as 14.3 g tTHR (11.8 g dTHR) per kilogram of litter gain. 相似文献
33.
Currently, the pork industry attempts to formulate energy levels in swine diets to within a tolerance of 1.5%. This is difficult to achieve in practice when the energy content of primary ingredients fluctuates by up to 15%. This experiment was carried out to define the sources of variation in the energy content of barley and to develop a practical method to accurately estimate the DE and ME content of individual barley samples. Four samples of each of five covered barley varieties (AC Lacombe, B-1602, Bedford, Harrington, and Manley) were collected to obtain a range of quality within each variety. Five measurements were collected on each barley sample using 60 crossbred barrows in an apparent total tract digestibility study. The barrows, average BW of 35.3 kg, were housed in individual metabolism crates to facilitate separate collection of urine and feces. Five-day collection periods followed 5-d diet acclimation periods. Levels of total beta-glucan, ADF, CP, and starch (90% DM) in the 20 barley samples ranged from 2.7 to 4.5%, 4.5 to 9.2%, 10.8 to 15.1%, and 42.3 to 53.4%, respectively. The mean DE and ME content of the 20 samples were 2,934 and 2,857 kcal/kg (90% DM), respectively, and varied among samples by 15.2% (447 kcal). The complex structural cell wall carbohydrates seemed to have the greatest influence on the energy content of individual barley samples. The ADF fraction alone accounted for 85% of the total variation in energy content of the 20 samples. Converted into a prediction equation, DE = 3,526 - 92.8 x ADF (90% DM), the ADF content was used to estimate the DE content of barley with 85% accuracy. This experiment confirms the large variation in the energy content of barley, describes the factors that influence this variation, and presents equations based on chemical and(or) physical measurements that may be used to predict the DE and ME content of individual barley samples. 相似文献