A Simulative Study on Effects of Climate Warming on Nutrient Contents and In Vitro Digestibility of Herbage Grown in Qinghai-Xizang Plateau

The increasing trend of air temperature along with the climate warming has been accepted gradually by scientists and by the general public. Qinghai_Xizang Plateau, a unique geographic unit due to high_altitude climate, is one of the most susceptible regions to climate warming. Its ecosystem is very fragile and sensitive to climate change. In order to get a better understanding of the impacts of climate warming on the nutrient contents of herbage grown in Qinghai_Xizang Plateau, a simulative study was implemented at Daban Moutain by using temperature differences resulted from sites selected at different altitudes and nutrient contents and in vitro digestibility were determined for assessing the quality of the grown herbage. There were significant downtrends in crude protein (CP), ether extract (EE) and nitrogen free extract (NFE) contents of herbage along with the increase of temperature. It had a positive correlation between temperature and content of acid detergent fibre (ADF), acid detergent lignin (ADL) in herbage. In vitro digestibility of herbage decreased along with the increase of temperature. The results of this study indicated that climate warming significantly influence nutrient contents and in vitro digestibility of herbage grown in Qinghai_Xizang Plateau. It is suggested that the future climate warming especially the gradual rise of the night temperature could cause negative effect on herbage quality grown in Qinghai_Xizang Plateau by decreasing CP, EE, and NFE contents and increasing some indigestible ingredients such as crude fibre (CF), neutral detergent fibre (NDF), ADF, and ADL. This, consequently, decreases the ruminant assimilation ability.

Performance and Ruminal Characteristics of Beef Cattle Fed Four Different Hybrids Sorghum Silages

This study was conducted to evaluate the intake, total and partial digestibility of nutrient, ruminal pH and ammonia concentration, microbial protein synthesis and performance in crossbred Holstein × Zebu cattle fed four different hybrids sorghum silages （1F305, XBF60329, BRS610, Volumax）. In Experiment 1, four rumen and abomasum fistulated steers, 400 ± 80 kg, distributed in a 4 × 4 Latin Square, were used. In Experiment 2, 28 crossbred Holstein × Zebu steers, 350 ± 50 kg, distributed in a randomized block design with four treatments and seven replicates, were used. In Experiment 1, it was observed that nutrient intake, as well as total, ruminal and intestinal digestibility of nutrient, were not affected （P 〉 0.05） by diets, except for total apparent digestibility of neutral detergent fiber （NDFap）, which was lower for the BRS610 hybrid. There was lower NDFap ingestion in animals that received a diet containing silage from the BRS610 hybrid, however, the lowest intake non-fibrous carbohydrates （NFC） was observed for the diet containing silage from the Volumax hybrid. In Experiment 2, nutrient intake were not affected by the diets （P 〉 0.05）, whereas, NDFap intake was lesser for hybrid BRS610. It was found that daily weight gain and feed conversion were not affected by different silages diets. Therefore, it may be concluded that the diets used were nutritionally equivalent, as they promoted similar animal performance without affecting ruminal parameters.

Impacts of High Fiber Diet on Digestion and Absorption of Minerals in Growing Pigs

The study was conducted to investigate the effects of feeding high-fiber diet （HFD） on apparent total tract digestibility （ATTD） and absorption of minerals in growing pigs. Sixteen barrows averaging 16.39 kg were randomly assigned to one of four diets after metabolic crate assignment with individual pig serving as experimental unit. Diets include： a corn-soybean meal based low-fiber diet （LFD）, as the control （CON） and 3 HFD （D1, D2 and D3）, each containing 5% sugar beet pulps and a 1：2, 1：1 and 2：1 oats to barley ratios, respectively, replacing 47% of the corn in the diet. Diets were formulated to meet nutrient requirements, however, the fiber content of the LFD was substantially lower than the average of the HFD （8.38% vs. 22.40%）. Feed allowance was limited to 10% of average body weight and fed twice/d. The study period was divided into 10 d of adjustment and 5 d of feces collection. Data collected were analyzed using SAS, GLIMMIX procedure where animals were considered random effects, and minerals were fixed. Results of the study show that digestibility of Ca in pigs fed HFD was lower （P 〈 0.05） than in pigs fed LFD. On the other hand, the apparent digestibility of P, K, Na, S and Zn in pigs fed D2 and D3 were higher （P 〈 0.05） than in pigs fed CON diet. It was also observed that digestibility of Ca, P, K, Na, S and Zn in pigs fed D1 were lower （P 〈 0.05） than in CON, D2 or D3 fed pigs. Therefore, it was concluded that while feeding HFD reduced availability of Ca, the availability of P, K, Na and S to pigs improved as the oat to barley ratio in the diet increased.

噬纤维菌和生孢噬纤维菌作为饲用蛋白质的综合评价

探索噬纤维菌(Cytophaga)和生孢噬纤维菌(Sporocytophaga)作为单细胞蛋白的潜力,旨在开发非常规蛋白质饲料。通过大量收集哈氏噬纤维菌和生孢噬纤维菌的菌体,检测蛋白质和氨基酸含量,并采用胃蛋白酶-胰蛋白酶体外两步消化法测定菌体蛋白消化率。研究结果显示:哈氏噬纤维菌和生孢噬纤维菌的菌体蛋白质含量50%左右,必需氨基酸含量与酵母菌相当;用其发酵液喂养昆明小鼠30 d,没有表现出毒性;哈氏噬纤维菌菌体的消化率在90%以上,生孢噬纤维菌的消化率也在65%左右,均远远高于对照酵母菌,为最突出的特点。希望从高消化率方面为单细胞蛋白的开发打开新思路。