Effect of raw soya bean particle size on productive performance and digestion of dairy cows

Differing soya bean particle sizes may affect productive performance and ruminal fermentation due to the level of fatty acid (FA) exposure of the cotyledon in soya bean grain and because the protein in small particles is more rapidly degraded than the protein in large particles, which influence ruminal fibre digestion and the amounts of ruminally undegradable nutrients. The objective of this experiment was to investigate the effects of raw soya bean particle size on productive performance, digestion and milk FA profile of dairy cows. Twelve Holstein cows were assigned to three 4 × 4 Latin squares with 21‐day periods. At the start of the experiment, cows were 121 days in milk (DIM) and yielded 30.2 kg/day of milk. Cows were fed 4 diets: (i) control diet (CO), without raw soya bean; (ii) whole raw soya bean (WRS); (iii) cracked raw soya bean in Wiley mill 4‐mm screen (CS4); and (iv) cracked raw soya bean in Wiley mill 2‐mm screen (CS2). The inclusion of soya beans (whole or cracked) was 200 g/kg on dry matter (DM) basis and partially replaced ground corn and soya bean meal. Uncorrected milk yield and composition were not influenced by experimental diets; however, fat‐corrected milk (FCM) decreased when cows were fed soya bean treatments. Soya bean diets increased the intake of ether extract (EE) and net energy of lactation (NE_L), and decreased the intake of DM and non‐fibre carbohydrate (NFC). Ruminal propionate concentration was lower in cows fed WRS than cows fed CS2 or CS4. Cows fed cracked raw soya bean presented lower nitrogen in faeces than cows fed WRS. The milk of cows fed WRS, CS2 and CS4 presented higher unsaturated FA than cows fed CO. The addition of raw soya bean in cow diets, regardless of the particle size, did not impair uncorrected milk yield and nutrient digestion, and increased the concentration of unsaturated FA in milk. Cows fed cracked raw soya bean presented similar productive performance to cows fed whole raw soya bean.     

氨基酸在紫花苜蓿干草品质评定中的作用

试验旨在探究紫花苜蓿氨基酸在营养品质评定中的作用,以不同品种紫花苜蓿(皇后、WL319HQ和Bara310SC)为研究对象,测定并综合分析其产量(CL)、营养品质以及17种氨基酸含量.结果 显示:皇后的干草产量、粗脂肪含量显著高于WL319HQ和Bara310SC (P＜0.05);WL319HQ和Bara310SC的...     

Effects of guanidinoacetic acid on growth performance,creatine metabolism and plasma amino acid profile in broilers

The objective of this study was to assess the effects of guanidinoacetic acid (GAA) on growth performance, creatine deposition and blood amino acid (AA) profile on broiler chickens. In Exp. 1, a total of 540 one‐day‐old Arbor Acres male broilers (average initial body weight, 45.23 ± 0.35 g) were divided randomly into five treatments with six replicates of 18 chicks each. Broilers were fed corn–soybean meal‐basal diets supplemented with 0, 600, 800, 1,000 or 1,200 mg/kg GAA for 42 days respectively. Results showed that dietary GAA inclusion increased average daily gain (ADG) and improved gain‐to‐feed ratio (G:F) from 1 to 42 days (p < 0.01). However, average daily feed intake was unaffected by dietary supplementation of GAA. As GAA inclusion increased, the contents of creatine in plasma and kidney were increased (linear, p < 0.01), while the contents of GAA and creatine in liver were decreased (linear, p < 0.01). Similarly, GAA supplementation was inversely related to concentrations of most essential AA in plasma. In Exp. 2, a total of 432 one‐day‐old Arbor Acres male broilers (average initial body weight, 39.78 ± 0.58 g) were divided randomly into four treatments with six replicates of 18 chicks each. Birds were fed a corn–soybean meal‐basal diet supplemented with 0, 200, 400 or 600 mg/kg GAA for 42 days respectively. Dietary inclusion of 600 mg/kg GAA significantly increased ADG and G:F of broilers (p < 0.05). In conclusion, dietary supplementation of 600–1,200 mg/kg GAA can effectively improve the growth performance in broiler chickens by affecting creatine metabolism and utilization efficiency of essential AA, and 600 mg/kg GAA is the minimum dose for improving performance.     

苜蓿青贮料替代苜蓿青干草对奶牛生产性能及乳品质的影响

试验旨在探讨苜蓿青贮料替代不同比例苜蓿青干草对奶牛生产性能、乳品质、营养物质表观消化率、血液生化指标及经济效益的影响。选取体重、产奶量、胎次相近的健康泌乳中期中高产中国荷斯坦奶牛15头,随机分为3组,每组5个重复,每个重复1头牛。对照组饲喂4.0 kg苜蓿青干草,试验A、B组分别用4.4,8.8 kg苜蓿青贮料代替2.0和4.0 kg等干物质的苜蓿青干草,正试期64 d。结果表明,1)各组间干物质采食量差异不显著(P>0.05),B组产奶量显著低于对照组(P<0.05),A组与对照组、B组间差异不显著(P>0.05); 2)用50%,100%的苜蓿青贮料替代等干物质的苜蓿青干草,其乳蛋白、乳脂率、乳糖均有所改善,但只有B组的乳脂率显著高于对照组(P<0.05),其余指标各组间差异均不显著(P>0.05);3)A、B组与对照组的中性洗涤纤维表观消化率、钙表观消化率无显著性差异(P>0.05),A、B组间粗蛋白和磷表观消化率差异不显著(P>0.05),但是粗蛋白表观消化率均显著低于对照组、磷表观消化率均显著高于对照组(P<0.05);4)苜蓿青贮料替代苜蓿青干草其血清总蛋白、白蛋白、血尿素氮、血糖、二氧化碳结合力等指标没有显著性改变(P>0.05);5)试验A、B组经济效益均有所增加,其中A组的净增收益最高,为0.61元/(头·d)。综上,用4.4 kg苜蓿青贮料代替2.0 kg苜蓿青干草对中高产奶牛是适宜的,能提高其生产性能,改善乳品质,增加收益。     

亚急性瘤胃酸中毒耐受性不同的奶牛血浆和乳中脂肪酸及代谢物组成分析

The present study aimed to explore the differences in plasma and milk metabolism of dairy cows with different subacute rumen acidosis (SARA) tolerance. Twelve fistulated Holstein dairy cows in mid lactation[days in milk=(114±22) d] were selected and fed the same diet consisting of 60% forage and 40% concentrate mixture. On days 20 and 21 of the trial period, the rumen pH was monitored at 0, 2, 4, 6, 8, and 12 h after morning feeding. Milk samples were collected before feeding in the morning and evening. Blood samples were collected from the jugular vein 6 h after morning feeding. All the milk and blood samples were stored in liquid nitrogen for subsequent fatty acid composition and metabolome analysis. Cows with the lowest and highest ruminal pH were assigned into the susceptible (SUS, n=4) and tolerant (TOL, n=4) groups, respectively. The fatty acid composition results showed that the proportions of ≤C16 fatty acids in the blood and milk were significantly increased in the SUS group (P< 0.05), while the proportions of > C16 fatty acids were significantly decreased (P< 0.05). The levels of the saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) in the milk were significantly decreased in the SUS group (P< 0.05). The LC-MS metabolomics results revealed that the L-phenylpyruvate was significantly reduced, while the levels of remaining MG (18: 0/0: 0/0: 0), 9-HODE, niacinamide, isovalerylcarnitine, phosphocreatine, L-glutamic acid, and 12(13) Ep-9-KODE were substantially increased in the SUS group. The results of milk metabolome analysis indicated that the levels of 1-stearoylphosphoglycerolserine and sphingosine were significantly increased, while the levels of 14 different metabolites were significantly decreased in the SUS group (P< 0.05), including glyceryl-phosphoryl-ethanolamine, glycerol 3-phosphate, and orotic acid. These differential metabolites were mainly involved in glycerophospholipid metabolism (P< 0.05), glycerolipid metabolism, and pantothenate and CoA biosynthesis. In conclusion, the fatty acids and metabolic profiles in the plasma and milk of cows with different tolerance to SARA were different. For the SUS group, the amino acid metabolism and the de novo synthesis ability of milk fat was enhanced in the plasma, while the ability to absorb long chain fatty acids from blood was weakened. At the same time, the levels of phospholipid, orotic acid and other nutrients were decreased in the milk, which indicated that the quality of milk was reduced for the SUS cows. © 2021, Editorial Office of Acta Prataculturae Sinica. All rights reserved.     

低蛋白氨基酸平衡日粮对产奶牛的生产性能和粪尿氮含量的影响

研究了低蛋白氨基酸平衡日粮对奶牛生产性能及氮排放的影响,探讨在不影响生产性能的前提下减少奶牛粪尿中氮的排放量。选择30头年龄、胎次、泌乳期和产奶量相近的荷斯坦奶牛,随机分为3组,每组10头,分别为对照组(饲喂基础日粮配方),试验Ⅰ组和Ⅱ组在基础日粮配方上分别减少0.80%和1.66%的氮(粗蛋白质),分别添加过瘤胃赖氨酸(RPLys)24.6 g/d+过瘤胃蛋氨酸(RPMet)10.4 g/d、RPLys 25.7 g/d+RPMet 9.4 g/d平衡日粮中的氨基酸。预饲期7 d,正试期42 d。测定产奶量、乳成分、表观消化率及粪尿氮含量。结果显示:与对照组相比,试验Ⅰ、Ⅱ组的采食量、4%的标准奶产量、乳成分和日粮表观消化率无显著变化(P0.05);试验Ⅰ组和试验Ⅱ组的粪尿氮排放量较对照组分别降低了7.67%和15.19%(P0.05);奶牛经济效益与对照组相比,每天分别增加了0.45元/头和3.17元/头。上述结果表明,在氨基酸平衡的基础上适当降低日粮蛋白不影响奶牛生产性能,同时还减轻氮排泄对环境的污染,为低蛋白氨基酸平衡日粮的实际应用提供依据。     

Effect of monensin and vitamin E on milk production and composition of lactating dairy cows

Feeding unsaturated oils to lactating dairy cows impair ruminal biohydrogenation (BH) of unsaturated fatty acids (USFA) and increase ruminal outflow of BH intermediates such as trans‐10, cis‐12 CLA that are considered to be potent inhibitors of milk fat synthesis. Supplementing lactating dairy cow’s rations containing plant origin oils with monensin and/or vitamin E may minimise the formation of trans‐10 isomers in the rumen, thereby preventing milk fat depression. Therefore, this study was conducted to evaluate the effects of monensin and vitamin E supplementation in the diets of lactating dairy cows containing whole cottonseed, as the main source of FA on feed intake, milk production and composition, milk fatty acid profile, efficiency of nitrogen (N) utilisation, efficiency of net energy (NE) utilisation and nutrients digestibilities. Four multiparous Holstein lactating dairy cows (86 ± 41 days in milk) were assigned to a balanced 4 × 4 Latin square design. Each experimental period lasted 21 days with a 14 days of treatment adaptation and a 7 days of data collection. The control diet was a total mixed ration (TMR) consisted of 430 g/kg forage and 570 g/kg of a concentrate mixture on dry matter (DM) basis. Cows were randomly assigned to one of the four dietary treatments including control diet (C), control diet supplemented with 150 mg of vitamin E/kg of DM (E), control diet supplemented with 24 mg of monensin/kg of DM (M) and control diet supplemented with 150 mg of vitamin E and 24 mg of monensin/kg of DM (EM). Dry matter intake (DMI) ranged from 19.1 to 19.5 kg/d and was similar among the dietary treatments. Dietary supplementation with vitamin E or monensin had no effect on milk production, milk fat, protein and lactose concentrations, efficiency of utilisation of nitrogen and net energy for lactation (NE_L). Digestibility of DM, organic matter (OM), crude protein (CP) and ether extract (EE) was not affected by the dietary treatments. Digestibility of neutral detergent fibre (NDF) was higher in cows fed with the M and EM diets in relation to those fed the C and E diets. The concentrations of C4:0, C6:0, C8:0, C10:0, C12:0, C14:0, C15:0, trans‐10‐16:1, cis‐9‐16:1, 17:0, 18:0, trans‐11‐18:1, cis‐9‐18:1, cis‐9, trans‐11 conjugated linoleic acid (CLA), trans‐10, cis‐12 CLA, and 18:3n‐3 FA in milk fat were not affected by the dietary supplementations. While feeding the M diet tended to decrease milk fat concentration of C16:0, the milk fat concentration of C18:2n‐6 FA tended to be increased. Dietary supplementation with vitamin E or monensin had no effect on milk fat concentrations of saturated, unsaturated, monounsaturated, polyunsaturated, short chain and long chain FA, but feeding the M diet numerically decreased milk fat concentration of medium chain fatty acids (MCFA). The results showed that vitamin E and/or monensin supplementations did not improve milk fat content and did not minimise the formation of trans‐10 FA isomers in the rumen when whole cottonseed was included in the diet as the main source of fatty acids.     

Effects of rice straw particle size on digesta particle size distribution,nitrogen metabolism,blood biochemical parameters,microbial amino acid composition and intestinal amino acid digestibility in goats

Effects of rice straw particle size and physically effective neutral detergent fiber (peNDF) on particle size distribution of different digestive tract, nitrogen (N) metabolism, blood biochemical parameters, microbial amino acid (AA) composition and intestinal AA digestibility in goats were investigated. A 4 × 4 Latin square design was employed using four mature Liuyang black goats fitted with permanent ruminal, duodenal, and terminal ileal fistulae. During each of the four periods, goats were offered one of four diets that were similar in chemical composition, but varied in particle sizes and peNDF through alteration of the theoretical cut length of rice straw (10, 20, 40 and 80 mm, respectively). Dietary peNDF contents of four diets were 17.4, 20.9, 22.5 and 25.4%, respectively. Results showed that increasing particle size of rice straw and dietary peNDF significantly affected the particle size distributions of digesta in rumen, duodenum and ileum, except feces. However, increasing particle size of rice straw and peNDF did not affected N metabolism in goats, except the increased apparent N digestibility in rumen and large intestine, and the decreased apparent N digestibility in small intestine. Furthermore, increasing particle size of rice straw and peNDF showed little influence on the profile of blood biochemical parameters, microbial AA composition and intestinal AA digestibility in goats.     

Milk protein responses to balanced amino acid and removal of Leucine and Arginine supplied from jugular‐infused amino acid mixture in lactating dairy cows

This study was undertaken to evaluate the milk protein response when cows were supplied a balanced AA profile and to determine whether a deficiency of Leucine (Leu) or Arginine (Arg) had a negative effect on milk protein. Eight mid‐lactation Holstein cows were randomly assigned to 5‐day continuous jugular infusions of saline (CTL), EAA mixture prepared on the profile of casein and supplied (in % of lysine (Lys)) 100% of Lys, 33.3% of methionine (Met), 110.2% of Leu, 43.6% of Arg, 50.8% of threonine (Thr), 81.6% of valine (Val), 69.7% of isoleucine (Ile), 61.4% of phenylalanine (Phe) and 34.2% of histidine (His) (Casein, 160 g/d), EAA mixture excluding Leu (?Leu, 163 g/d) or EAA mixture excluding Arg (?Arg, 158 g/d) in a duplicated 4 × 4 Latin square design with four infusion periods separated by 7‐day interval period. The basal diet supplied 1.6 Mcal NE_L and 94.4 g MP per 1 kg DM to meet requirements for lactation. The Casein treatment provided a balanced supply (in % of MP) of 10.3% Leu and 5.3% Arg, whereas in the two subsequent ?Leu and ?Arg treatments, the concentration of Leu and Arg was reduced to 8.4 and 4.6% respectively. Dry matter intake (15.4 kg/day) was not affected by treatments. The Casein treatment increased milk yield (14.9%, p < 0.001), milk protein yield (120 g, p < 0.001) and milk protein efficiency (0.03, p = 0.099) than CTL treatment. However, the ?Leu treatment decreased the responses of above‐measured parameters by 6.25%, 70 g, 0.05 (p < 0.06) (compared with Casein). These effects of Leu were related to decreased Leu concentration and improved concentration of Ile and Val in plasma. The ?Arg treatment decreased the plasma Arg concentration than the Casein treatment, whereby resulted in the decrease of milk yield (5.7%, p = 0.073), milk protein yield (60 g, p = 0.011) and milk protein efficiency (0.04, p = 0.037). In conclusion, supply of EAA profile of casein can increase the lactation production in dairy cows, and 8.6% of Leu in MP partly limits the milk protein response when the requirements of Lys, Met and His were met. The level of Arg at 4.6% MP is not deemed to an ideal profile, as evidenced by decreased milk protein efficiency.     

Effects of grass hay proportion in a corn silage‐based diet on rumen digesta kinetics and digestibility in dairy cows

In this study, we aimed to evaluate the effects of six levels of orchardgrass hay (GH) proportion (0%, 10%, 20%, 30%, 40% or 50% of dry matter) in finely chopped corn silage (CS)‐based diets on digesta kinetics of CS and GH in the rumen. Six non‐lactating, rumen‐cannulated Holstein cows were used in a 6 × 6 Latin square design. Ruminal digesta kinetics was measured by ruminal dosing of feed particle markers (dysprosium for CS, erbium for GH) followed by fecal sampling. The increase of GH proportion had a quadratic effect (P < 0.01) on total tract digestibility of neutral detergent fiber (NDF) and acid detergent fiber. The proportion of GH did not affect the particle size distribution of rumen digesta, total weight of dry matter or NDF in the rumen. The rates of large particle size reduction in the rumen for CS tended to increase linearly with increasing GH proportion (P = 0.077). A quadratic effect (P < 0.05) was found with increasing the GH proportion for the ruminal passage rate of small GH particles, but not for CS particles. The results suggested that associative effects between CS and GH could be generated on rumen digesta kinetics when cows were fed a CS‐based diet with an increased proportion of GH.     

不同精粗比全混合日粮饲养技术对南方奶牛采食行为、产奶性能和血清游离氨基酸的影响

研究了具有南方奶牛日粮类型特征的全混合日粮饲养技术不同精粗比(T1,60∶40;T2,55∶45;T3,50∶50;T4,45∶55;T5,40∶60)对奶牛的采食行为、产奶性能和血清游离氨基酸的影响。试验结果表明,在全混合日粮饲养技术下,日粮精粗比的增加,奶牛的干物质采食量从T5组的13.57 kg/d显著降低至T1组的12.70 kg/d(P<0.05),咀嚼时间从T5组的786.50 min/d极显著降低至T1组的607.83 min/d(P<0.01);奶牛的产奶量、4%标准奶产量、乳糖、乳总固形物、总非脂固形物产量均随日粮精粗比增加而显著增加(P<0.05),以60%精料添加量的T1组为最高,分别为13.92,13.25,0.65,1.73和1.20 kg/d;但对奶牛的血清游离氨基酸含量无显著影响(P>0.05)。表明在南方奶牛典型日粮采用全混合日粮饲养技术时,日粮精粗比的增加可提高奶牛的产奶性能,降低奶牛的干物质采食量、咀嚼时间,对奶牛的血清游离氨基酸含量没有显著影响。     

Effects of feeding ratio of beet pulp to alfalfa hay or grass hay on ruminal mat characteristics and chewing activity in Holstein dry cows

The influence of the feeding ratio of a non‐forage fiber source and hay on ruminal mat characteristics and chewing activity was evaluated in dairy dry cows. Cows were fed four different diets: the ratios of alfalfa hay (AH) to beet pulp (BP) were 8:2 (dry matter basis, A8B2) and 2:8 (A2B8), and those of grass hay (GH) to BP were 8:2 (G8B2) and 2:8 (G2B8). Total eating time was decreased with increasing BP content (P < 0.01). Total rumination time for AH was shorter than that for GH (P < 0.01), and it decreased with increasing BP content (P < 0.01). The ruminal mat was detected by using a penetration resistance test of the rumen digesta. Penetration resistance value (PRV) of ruminal mat was highest with the G8B2 diet and PRV decreased with increasing BP content (P < 0.05) and feeding AH (P < 0.05). Thickness of the ruminal mat was greater for increasing BP content (P < 0.05). Simple linear regression of ruminal mat PRV on total rumination time resulted in a high positive correlation (r = 0.744; P < 0.001; n = 16). The results demonstrated that increasing the PRV of the ruminal mat stimulated rumination activity and a ruminal mat could be formed, although it was soft even when cows were offered a large quantity of BP.     

Constraints on the utilization of cereal straw in lactating dairy cows: A review from the perspective of systems biology

Cereal straw, a human inedible crop byproduct, can be used as a roughage source in ruminants. However,the nutrition density and palatability are very low, limiting its efficient utilization in animal production.This review aims to systematically provide an overview of the limitations of cereal straws, which is crucial for developing new strategies to enhance the efficient use of cereal straws by lactating dairy cows.Evolutionary molecular biology makes it possible to comprehensively understand t...     

Effect of wood kraft pulp feed on digestibility,ruminal characteristics,and milk production performance in lactating dairy cows

The effect of wood kraft pulp (KP) feed on dietary digestibility, ruminal fluid pH, rumen fermentation characteristics, and milk production performance in lactating dairy cows was examined. Four lactating dairy cows were used for the feeding experiment by the cross‐over design. The control group and KP group were set up as treatments. The control group was fed total mixed ration (TMR) (40% roughage and 60% concentrate) and the KP group was fed TMR containing 12% KP that replaced half of the rolled corn in the control diet. The dry matter intake, digestibility of the feed components, and milk yield were not significantly different between control group and KP group. The number of times that the ruminal fluid pH was below 6.1 tended to decrease in the KP group compared to the control group (p < 0.10). The acetic acid ratio in the ruminal fluid of the KP group increased compared to the control group (p < 0.05) and the propionic acid ratio in the ruminal fluid of the KP group decreased compared to the control group (p < 0.05). The acetate:propionate acid ratio was increased in the KP group compared with the control group (p < 0.05). Lipopolysaccharide levels in the ruminal fluid of the KP group tended to decrease compared to the control group (p < 0.10). Based on these results, it was indicated that the use of KP feed for lactating dairy cows induced the same rumen fermentation characteristics as those in cows given a large amount of roughage without depressing milk productivity. Therefore, KP could be a valuable feed resource substitute for grains, which would also reduce the risk for subacute rumen acidosis.     

Branched‐chain amino acid ratios in low‐protein diets regulate the free amino acid profile and the expression of hepatic fatty acid metabolism‐related genes in growing pigs

Liver metabolism is affected by nutrients. The aim of this study was to explore the effects of low‐protein diets (17% crude protein, CP) supplemented with branched‐chain amino acids (BCAAs), including leucine (Leu), isoleucine (Ile) and valine (Val), on hepatic amino acid profile and lipid metabolism in growing pigs. The ratio of Leu : Ile : Val in all groups was 1 : 0.51 : 0.63 (20% crude protein, CP), 1 : 1 : 1 (17% CP), 1 : 0.75 : 0.75 (17% CP), 1 : 0.51 : 0.63 (17% CP) and 1 : 0.25 : 0.25 (17% CP) respectively. Results revealed that compared to the positive control group (1 : 0.51 : 0.63, 20% CP), the low‐protein diets significantly augmented the concentrations of most essential amino acids and non‐essential amino acids (p < .05), with the greatest values observed in the 1 : 0.25 : 0.25 group. Moreover, relative to the control, the low‐protein diets with the Leu : Ile : Val ratio ranging from 1 : 0.75 : 0.75 to 1 : 0.25 : 0.25 markedly downregulated the mRNA abundance of acetyl‐CoA carboxylase (ACC), lipoprotein lipase (LPL) and fatty acid‐binding protein 4 (FABP‐4) (p < .05), and upregulated the mRNA expression of hormone‐sensitive lipase (HSL), peroxisome proliferator‐activated receptor‐g coactivator‐1α (PGC‐1α), uncoupling protein 3 (UCP3) and liver carnitine palmitoyltransferase 1 (L‐CPT‐1) (p < .05). Therefore, our data suggest that protein‐restricted diets supplemented with optimal BCAA ratio, that is, 1 : 0.75 : 0.75–1 : 0.25 : 0.25, induce a shift from fatty acid synthesis to fatty acid oxidation in the liver of growing pigs. These effects may be associated with increased mitochondrial biogenesis.     

日粮阴阳离子差在泌乳奶牛日粮中的应用

日粮阴阳离子差（DCAD）可调控家畜体内的酸碱平衡。近年来，由于其对泌乳奶牛生产性能的影响而越来越受到研究者的重视。文章就阴阳离子差的计算，阴阳离子差对泌乳奶牛干物质采食量、泌乳量和乳成分、瘤胃参数的影响，及对DCAD在我国泌乳奶牛日粮中的应用的展望作了综合阐述。     

氨基酸复合微肥对苜蓿生产和营养品质的影响

试验阐明了在景泰的土壤条件下施用氨基酸复合微肥对紫花苜蓿Medicago sativa生长、品质和营养吸收的影响,为苜蓿的合理施肥提供了依据.结果表明:氨基酸复合微肥能够不同程度地增加株高并提高草产量.适当施用氨基酸复合微肥还能提高苜蓿粗蛋白和粗脂肪的含量.且在此试验条件下苜蓿喷施氨基酸复合微肥的最佳用量是1 350 mL/hm2.     

Changes in the viscoelastic behaviour of the rumenal digesta mat of sheep fed on pasture or chaffed lucerne hay

We examined the changes in the physical properties of the digesta mat over a period of 24 h after cessation of feeding, in sheep that had been maintained on pasture or fed chaffed lucerne hay. The dry matter content of the digesta mat declined at similar rates in both dietary groups, although it was generally higher in sheep fed lucerne. Median particle size declined in the digesta mats of both dietary groups at similar rates in samples taken after 8 h, but median particle size was significantly greater in sheep fed chopped lucerne hay than in those fed grass. Thus, particles were not reduced to a common size suggesting that factors in addition to particle size governed the rate of breakdown of the rumen mat. The relationship between the elastic and loss moduli was of a consistent pattern in all samples taken from the rumen mat indicating that it behaved as a weak gel. The elastic and loss moduli of the digesta mats of sheep that had been fed pasture or chopped lucerne hay converged to similar values after 12 h and declined broadly at similar rates after this. The relationship between these two moduli and the dry matter content of the rumen mat were of similar curvilinear form for sheep on both diets. These findings suggest that the rate of breakdown of the rumen mat is more likely to be governed by its composite behaviour than by the size of the constituent particles.     

Amino acid profiles of rumen undegradable protein: a comparison between forages including cereal straws and alfalfa and their respective total mixed rations

Optimizing the amino acid (AA) profile of rumen undegradable protein (RUP) can positively affect the amount of milk protein. This study was conducted to improve knowledge regarding the AA profile of rumen undegradable protein from corn stover, rice straw and alfalfa hay as well as the total mixed ratio diets (TMR) based on one of them as forage source [forage‐to‐concentrate ratio of 45:55 (30% of corn stover (CS), 30% of rice straw (RS), 23% of alfalfa hay (AH) and dry matter basis)]. The other ingredients in the three TMR diets were similar. The RUP of all the forages and diets was estimated by incubation for 16 hr in the rumen of three ruminally cannulated lactating cows. All residues were corrected for microbial colonization, which was necessary in determining the AA composition of RUP from feed samples using in situ method. Compared with their original AA composition, the AA pattern of forages and forage‐based diets changed drastically after rumen exposure. In addition, the extent of ruminal degradation of analysed AA was not constant among the forages. The greatest individual AA degradability of alfalfa hay and corn stover was Pro, but was His of rice straw. A remarkable difference was observed between microbial attachment corrected and uncorrected AA profiles of RUP, except for alfalfa hay and His in the three forages and TMR diets. The ruminal AA degradability of cereal straws was altered compared with alfalfa hay but not for the TMR diets. In summary, the AA composition of forages and TMR‐based diets changed significantly after ruminal exposure, indicating that the original AA profiles of the feed cannot represent its AA composition of RUP. The AA profile of RUP and ruminal AA degradability for corn stover and rice straw contributed to missing information in the field.     

Performance of lactating dairy cows fed a diet based on treated rice straw and supplemented with pelleted sweet potato vines

The purpose of this study was to evaluate the effects of sweet potato vine pellet (SWEPP) in concentrate diets on nutrient digestibility and rumen ecology in lactating dairy cows fed on urea-treated rice straw. Three multiparous Holstein crossbred cows in mid-lactation were randomly assigned according to a 3?×?3 Latin square design, and the treatments were as follows: T1 = control (no supplementation), T2 = supplementation of sweet potato vine pellet with 50 g/kg urea (SWEPP I) at 300 g/head/day, and T3 = supplementation of sweet potato pellet with 100 g/kg urea (SWEPP II) at 300 g/head/day, in concentrate diets, respectively. The result revealed that supplementation of SWEPP did not affect feed intake, ruminal pH, and blood urea nitrogen (P?>?0.05). However, apparent digestibilities of organic matter, crude protein, and neutral detergent fiber were higher in SWEPP II than those in others. Furthermore, ruminal ammonia nitrogen (NH₃-N) and milk yield were significantly higher (P?<?0.05) in animals fed with SWEPP II than those fed with SWEPP I and control, respectively. In addition, there were no differences in purine derivatives and microbial nitrogen supply among all the treatments. Based on this study, it could be concluded that SWEPP is a good source of supplement which resulted in significant improvement in apparent digestibility, rumen fermentation, and milk yield in lactating dairy cows fed on urea-treated rice straw.