Effects of concentrate‐to‐forage ratios and 2‐methylbutyrate supplementation on ruminal fermentation,bacteria abundance and urinary excretion of purine derivatives in Chinese Simmental steers

This study evaluated the effects of dietary concentrate levels and 2‐methylbutyrate (2MB ) supplementation on performance, ruminal fermentation, bacteria abundance, microbial enzyme activity and urinary excretion of purine derivatives (PD ) in steers. Eight ruminally cannulated Simmental steers (12 months of age; 389 ± 3.7 kg of body weight) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement. Moderate‐concentrate (400 g/kg diet [MC ]) or high‐concentrate (600 g/kg diet [HC ]) diets were fed with or without 2MB (0 g/day [2MB ?] or 15.0 g/day [2MB +]). Dry matter intake and average daily gain increased, but feed conversion ratio decreased with the HC diet or 2MB supplementation. Ruminal pH decreased, but total volatile fatty acid increased with the HC diet or 2MB supplementation. Molar proportion of acetate and acetate‐to‐propionate ratio decreased with the HC diet, but increased with 2MB supplementation. Propionate molar proportion and ruminal NH ₃‐N content increased with the HC diet, but decreased with 2MB supplementation. Neutral detergent fibre degradability decreased with the HC diet, but increased with 2MB supplementation. Crude protein degradability increased with the HC diet or 2MB supplementation. Abundance of Ruminococcus albus , Ruminococcus flavefaciens , Fibrobacter succinogenes and Bufyrivibrio fibrisolvens as well as activities of carboxymethyl cellulase, cellobiase, xylanase and pectinase decreased with the HC diet, but increased with 2MB supplementation. However, abundance of Prevotella ruminicola and Ruminobacter amylophilus as well as activities of α‐amylase and protease increased with the HC diet or 2MB supplementation. Total PD excretion also increased with the HC diet or 2MB supplementation. The results suggested that growth performance, ruminal fermentation, CP degradability and total PD excretion increased with increasing dietary concentrate level from 40% to 60% or 2MB supplementation. The observed diet × 2MB interaction indicated that supplementation of 2MB was more efficacious for improving growth performance, ruminal fermentation and total PD excretion with promoted ruminal bacteria abundance and enzyme activity in the MC diet than in the HC diet.     

异戊酸对西门塔尔牛瘤胃发酵及尿嘌呤衍生物的影响

选用4头体重(420±8.6)kg,年龄2.5岁装有永久性瘤胃瘘管的中国西门塔尔牛阉牛,采用4×4拉丁方设计,以混合精料和玉米秸秆为基础日粮,研究异戊酸(0、0.02、0.04和0.06 g/kgW)对瘤胃pH、NH3-N、VFA、营养物质降解率及尿嘌呤衍生物浓度的影响。结果表明:0.06 g/kgW组显著降低瘤胃pH(P<0.05),饲喂后3-6 h,0.04 g/kgW组和0.06 g/kgW组NH3-N浓度显著低于对照和0.02 g/kgW组(P<0.05);0.04 g/kgW组和0.06 g/kgW组,豆粕干物质、有机物质和粗蛋白质有效降解率显著低于对照(P<0.05);0.04 g/kgW组玉米秸秆干物质、有机物质、中性洗涤纤维和酸性洗涤纤维的有效降解率显著提高(P<0.05),0.04 g/kgW组瘤胃乙酸、丁酸、乙酸/丙酸比例、总挥发性脂肪酸和尿嘌呤衍生物显著增加(P<0.05)。异戊酸的适宜添加水平为0.04g/kgW。     

不同饲养水平下瘤胃微生物蛋白合成效率的研究

用6头装有瘤胃、十二指肠、回肠瘘管的西门塔尔杂交阉牛,以Cr2O3为指示剂测定食糜流量,用嘌呤氧化法测定RNA当量,研究不同饲养水平下,西门塔尔杂交阉牛瘤胃微生物蛋白的合成效率。结果表明,瘤胃微生物蛋白的合成效率随饲养水平的变化呈规律性变化趋势。其中低饲养水平、中饲养水平较高,高饲养水平较低。在低、中、高3种饲养水平下,瘤胃微生物对瘤胃降解氮(RDN)的转化效率(MN/RDN,g/g)分别为0.64±0.08,0.52±0.16,0.23±0.03,对瘤胃可利用能(RDOM,瘤胃可消化有机物)的利用效率(MN/RDOM,g/kg)分别为24.66±4.96,27.17±15.18,11.92±1.86。     

埋植Revalor对秦川阉牛肉用性能的作用

 将40头约13月龄的秦川阉牛按体重分为10个单位组，每组4头，其中1头作对照，3头埋植Pevalor，经过89天肥育试验后进行屠宰和肉脂品质测定。结果表明，Revalor显著降低了血清脲氮含量，极显著提高了血清谷草转氨酶活性；使得秦川阉牛日增重和饲料报酬分别提高19.2%和17.8%，增加了胴体瘦肉量，减少了脂肪沉积；提高了胴体蛋白含量，明显改变了脂肪组织的脂肪酸组成，但对肌肉中17种水解氨基酸含量无明显影响。Revalor对秦川阉牛行为有一定的不良影响，使得争斗和爬跨活动频繁，逃跑距离增大，但并不严重，不足以构成饲养管理上的困难。     

Fat depot‐specific differences in leptin mRNA expression and its relation to adipocyte size in steers

ABSTRACT This experiment was conducted to investigate leptin mRNA expression, adipocyte size, and their relationship in several adipose tissues of fattening steers. Subcutaneous, perirenal, intermuscular and intramuscular adipose tissues were collected from three crossbred steers (Japanese Black cattle X Holstein) aged 21 months. The mRNA level and adipocyte diameter were determined in these adipose tissues. The intramuscular adipose tissue had a lower leptin mRNA level than the intermuscular and perirenal adipose tissues (P < 0.05). Leptin mRNA level was lower in the subcutaneous depot than in the intermuscular depot (P < 0.05). Adipocyte diameter was larger in the intermuscular adipose tissue than in the subcutaneous and intramuscular adipose tissues (P < 0.05). Leptin mRNA level was positively correlated with adipocyte diameter (r² = 0.81, P < 0.05). These results suggest that the cattle have fat depot‐specific differences in leptin gene expression, which are a result of a difference in adipocyte size.     

日粮添加不同水平蛋氨酸硒对肉牛营养物质代谢的影响

选用4头安装永久瘤胃瘘管的西门塔尔阉牛(体重为420kg、年龄2.5岁),采用4×4拉丁方设计,以混合精料和风干玉米秸秆作为基础日粮,研究1.3倍维持需要水平下,日粮添加不同水平蛋氨酸硒(0、0.3、0.6、0.9mg/kg,以干物质为基础)对营养物质代谢的影响。结果表明:0.3和0.6mg/kg组日粮OM、CP、EE、NFE、NDF、ADF表观消化率显著高于对照组(P<0.05);0.6和0.9mg/kg组DN、RN和RN/DN显著高于对照组(P<0.05);0.6mg/kg组与对照组相比Se、Ca、P、Cu、Fe、Mn的存留率显著提高,Zn、Mo和S的存留率无显著差异;0.6mg/kg组血清TG、GLU、ALB、TP、ALT、AST、SOD、GSH-px、GSH均显著高于对照组(P<0.05);0.6mg/kg组血清Se、Cu含量显著高于对照组(P<0.05)。     

Changes in Activities of Enzymes Related to Energy Metabolism in Peripheral Leukocytes of Fattening Steers

Glucose, triglyceride, cholesterol and immunoreactive insulin (IRI) concentrations, some enzyme activities in plasma, and activities of enzymes related to energy metabolism in peripheral leukocytes were measured in fattening Japanese Black Wagyu x Holstein steers fed on different diets at 8, 12, 16, 20 and 24 months of age. The plasma IRI concentrations at 20 and 24 months of age were significantly higher than those at 8 months of age. Activities of hexokinase (HK), glucose-6-phosphate dehydrogenase (G6PD), aspartate aminotransferase (AST), and malate dehydrogenase (MDH) in cytosolic fractions, and glutamate dehydrogenase (GLDH), MDH and AST in mitochondrial fractions in peripheral leukocytes of steers at 24 months of age were significantly higher than those at 8 months. Increasing plasma insulin concentration was considered to induce acceleration of glucose utilization in leukocytes of fattening steers. The cytosolic ratio of MDH/lactate dehydrogenase (LDH) activity in leukocytes increased significantly in the fattening process and was considered to be a useful indicator for evaluating changes in energy metabolism in steers.     

蛋氨酸硒对牛营养物质代谢和生化指标的影响

选用16头体重420kg、年龄2.5岁西门塔尔牛阉牛,采用随机区组设计分为4组,以蛋氨酸硒为硒源,在基础日粮中分别添加硒0、0.3、0.6和0.9mg/kg,研究蛋氨酸硒对西门塔尔牛营养物质消化代谢和理化指标的影响。结果表明,0.3和0.6mg/kg组日粮的有机物质、粗蛋白质、粗脂肪、中性洗涤纤维、酸性洗涤纤维消化率显著高于对照(P<0.05);0.6和0.9mg/kg组的消化氮、沉积氮和氮利用率显著高于对照(P<0.05);0.6mg/kg组的硒、钙、磷、锰、铜、钼的存留率显著提高(P<0.05),锌和硫的存留率无显著差异;0.6mg/kg组的血清甘油三酯、血糖、白蛋白、总蛋白、GPT、GOT、GSH-px和GSH均显著高于对照(P<0.05)。0.6和0.9mg/kg组丙二醛含量显著低于对照(P<0.05);0.6mg/kg组血清硒含量显著高于对照(P<0.05)。日粮加硒0.6mg/kg显著改善日粮营养物质消化代谢,提高了机体抗氧化能力,建议以蛋氨酸硒为硒源时日粮加硒0.60mg/kg。     

Effect of niacin supplementation in long‐distance transported steer calves

Long‐distance transportation has negative impacts on production and health in cattle. Feed and water are routinely deprived from cattle during transportation. We investigated whether niacin supplementation could improve niacin nutrition and mitigate the adverse effect of transportation with feed and water deprivation in steer calves. We also studied the adverse effect of feed and water deprivation in nontransported steer calves. Twelve calves were assigned to feed and water deprivation for 2 days, or full access to feed and water in experiment 1. Ten calves were assigned to 2‐day transportation with feed and water deprivation, or the transportation with feed and water deprivation, but with supplementation of rumen‐protected niacin at 100 g/day per head in experiment 2. Bodyweight was measured and blood was collected for 32 days in each experiment. Feed and water deprivation temporarily decreased serum glucose concentrations and bodyweight gain. Transportation with deprivation of feed and water caused a temporal decrease in bodyweight gain and serum albumin concentration, and a continuous decrease in serum glucose and total cholesterol concentrations, which was suppressed by niacin supplementation. Niacin supplementation increased blood niacin concentration. These results suggest that niacin supplementation mitigates adverse effects of transportation with feed and water deprivation in steer calves.     

日粮添加赛乐硒对西门塔尔牛瘤胃发酵和尿嘌呤衍生物含量的影响

选用7头体重420 kg,2.5岁装有永久性瘤胃瘘管的西门塔尔牛,采用7×7拉丁方设计,研究日粮添加赛乐硒(7.5,15.0和22.5 mg/d)和Na2SeO3(7.5,15.0和22.5 mg/d)对瘤胃发酵和尿嘌呤衍生物含量的影响。结果表明,15.0和22.5 mg/d赛乐硒组瘤胃pH值显著低于Na2SeO3组(P<0.05)。各处理组瘤胃氨态氮浓度显著低于对照组,但赛乐硒与Na2SeO3处理之间无显著差异(P>0.05)。22.5 mg/d赛乐硒组瘤胃乙酸浓度显著高于Na2SeO3组,赛乐硒各组丙酸浓度显著高于Na2SeO3各组及对照组,15.0和22.5 mg/d赛乐硒组瘤胃丁酸和总挥发性脂肪酸浓度显著高于Na2SeO3组,赛乐硒各组乙酸/丙酸显著低于Na2SeO3各组及对照组(P<0.05)。15.0mg/d赛乐硒组玉米秸秆干物质、有机物质、中性洗涤纤维和酸性洗涤纤维有效降解率显著高于其他处理(P<0.05)。15.0 mg/d赛乐硒组豆粕干物质有效降解率显著高于对照组,15.0 mg/d赛乐硒组豆粕粗蛋白质有效降解率显著高于7.5 mg/d赛乐硒组(P<0.05)。15.0 mg/d赛乐硒组尿嘌呤衍生物含量显著高于Na2SeO3组(P<0.05)。赛乐硒较Na2SeO3显著促进瘤胃发酵,促进瘤胃纤维等营养物质的分解,促进蛋白质的合成,适宜补充量为7.5~15.0 mg/d。