Tannins have been extensively studied to decrease nitrogen excretion, however, the effects of tannins on animal production were inconsistent. The objective was to evaluate the effects of a mixture of quebracho-chestnut tannin extract (QCTE) supplementation on the production performance, nutrient digestibility, rumen fermentation patterns, and N partitioning in dairy cows. Sixty multiparous Holstein cows (mean ± standard deviation; average 717 ± 51kg of body weight, 2.5 ± 0.2 of parity, 47 ± 1.9kg/d of milk production, 78 ± 3.2 d of days in milk were randomly divided into four groups. Cows in different groups were provided QCTE at doses of 0, 10, 20, and 30g/d per cow for 56 d. Although QCTE supplementation did not affect dry matter intake (DMI) and total-tract apparent digestibility of nutrients, milk yield and milk protein yield increased linearly (P = 0.01), and a trend for a linear (P = 0.07) increase in milk/DMI were observed with increasing QCTE supplementation. Increasing QCTE supplementation decreased the milk urea-N concentration and somatic cell count linearly (P < 0.05), tended to linearly (P < 0.1) decrease the concentration of blood urea-N and ruminal ammonia nitrogen, linearly (P < 0.05) increased levels of total antioxidant capacity and superoxide dismutase, and the molar proportions of ruminal propionate. Additionally, total N excretion was not affected by QCTE treatments, but QCTE supplementation linearly (P = 0.04) increased N utilization efficiency and tended to linearly (P = 0.1) decrease urea-N excretion in the urine. In conclusion, feeding QCTE at a dose of 30g/d per head to cows in early lactation could increase antioxidant enzyme activities, improve production performance, and decrease environmentally labile urinary N excretion under the conditions of the study.

Adequate energy supply is a crucial factor for maintaining the production performance in early lactating cows. Adding fatty acids to diets can improve energy supply, while the effect could be related to the chain length and degree of saturation of fatty acids. This study was conducted to evaluate the effect of different ratios of palmitic acid (C16:0) to oleic acid (cis-9 C18:1) on the production performance, nutrient digestibility, blood metabolites and milk fatty acids profile in early lactating dairy cows. Seventy-two multiparous Holstein cows (63.5 ± 2.61 d in milk) blocked by parity (2.39 ± 0.20), body weight (668.3 ± 20.1 kg), body condition score (3.29 ± 0.06), and milk yield (47.9 ± 1.63 kg) were used in a completely randomized design. Cows were divided into 3 groups with 24 cows in every group. Cows in 3 treatments were provided iso-energy and iso-nitrogen diets, whereas the C16:0 to cis-9 C18:1 ratio was different: (1) 90.9% C16:0 + 9.1% cis-9 C18:1 (90.9:9.1); (2) 79.5% C16:0 + 20.5% cis-9 C18:1 (79.5:20.5); (3) 72.7% C16:0 + 27.3% cis-9 C18:1 (72.7:27.3). Fatty acids were added at 1.3% in dry matter basis. Although the dry matter intake fat-corrected milk yield and energy-corrected milk yield were not affected, the milk yield, milk protein yield and feed efficiency increased linearly with the increasing of cis-9 C18:1 ratio. The milk protein percentage and milk fat yield did not differ among treatments, whereas the milk fat percentage tended to decrease linearly with the increasing of cis-9 C18:1 ratio. The lactose yield increased linearly and lactose percentage tended to increase linearly with increasing cis-9 C18:1 ratio, whereas the percentage of milk total solids and somatic cell count decreased linearly. Though the changes of body condition score were not affected by treatments, the body weight loss decreased linearly with the increasing of cis-9 C18:1 ratio. The effect of treatment on nutrient digestibility was limited, except a linear increase in ether extract and neutral detergent fiber digestibility with the increasing of cis-9 C18:1 ratio. There was a linear increase in the concentrations of plasma glucose, whereas the triglyceride and nonesterified fatty acid concentration decreased linearly with the increasing of cis-9 C18:1 ratio. As the cis-9 C18:1 ratio increased, the concentration of de novo fatty acids decreased quadratically, while the mixed and preformed fatty acids increased linearly. In conclusion, increasing cis-9 C18:1 ratio could increase production performance and decrease body weight loss by increasing nutrient digestibility, and the ratio had the most powerful beneficial effect on early lactating cows suggested by 72.7:27.3.

The dietary rumen-degradable starch (RDS) to rumen-degradable protein (RDP) ratio, denoted as the RDS-to-RDP ratio (SPR), has been proven to enhance in vitro rumen fermentation. However, the effects of dietary SPR in vivo remain largely unexplored. This study was conducted to investigate the effect of dietary SPR on lactation performance, nutrient digestibility, rumen fermentation patterns, blood indicators, and nitrogen (N) partitioning in mid-lactating Holstein cows. Seventy-two Holstein dairy cows were randomly assigned to three groups (24 head/group), balanced for (mean ± standard deviation) days in milk (116 ± 21.5), parity (2.1 ± 0.8), milk production (42 ± 2.1 kg/d), and body weight (705 ± 52.5 kg). The cows were fed diets with low (2.1, control), medium (2.3), or high (2.5) SPR, formulated to be isoenergetic, isonitrogenous, and iso-starch. The study consisted of a one-week adaptation phase followed by an eight-week experimental period. The results indicated that the high SPR group had a lower dry matter intake compared to the other groups (p < 0.05). A quadratic increase in milk yield and feed efficiency was observed with increasing dietary SPR (p < 0.05), peaking in the medium SPR group. The medium SPR group exhibited a lower milk somatic cell count and a higher blood total antioxidant capacity compared to other groups (p < 0.05). With increasing dietary SPR, there was a quadratic improvement (p < 0.05) in the total tract apparent digestibility of crude protein, ether extract, starch, neutral detergent fiber, and acid detergent fiber. Although no treatment effect was observed in rumen pH, the rumen total volatile fatty acids concentration and microbial crude protein synthesis increased quadratically (p < 0.05) as dietary SPR increased. The molar proportion of propionate linearly increased (p = 0.01), while branched-chain volatile fatty acids linearly decreased (p = 0.01) with increasing dietary SPR. The low SPR group (control) exhibited higher concentration of milk urea N, rumen ammonia N, and blood urea N than other groups (p < 0.05). Despite a linear decrease (p < 0.05) in the proportion of urinary N to N intake, increasing dietary SPR led to a quadratic increase (p = 0.01) in N utilization efficiency and a quadratic decrease (p < 0.05) in the proportion of fecal N to N intake. In conclusion, optimizing dietary SPR has the potential to enhance lactation performance and N utilization efficiency. Based on our findings, a medium dietary SPR (with SPR = 2.3) is recommended for mid-lactating Holstein dairy cows. Nevertheless, further research on rumen microbial composition and metabolites is warranted to elucidate the underlying mechanisms of the observed effects.

BACKGROUND:The rumen of neonatal calves has limited functionality, and establishing intestinal microbiota may play a crucial role in their health and performance. Thus, we aim to explore the temporal colonization of the gut microbiome and the benefits of early microbial transplantation (MT) in newborn calves. RESULTS:We followed 36 newborn calves for 2 months and found that the composition and ecological interactions of their gut microbiomes likely reached maturity 1 month after birth. Temporal changes in the gut microbiome of newborn calves are widely associated with changes in their physiological statuses, such as growth and fiber digestion. Importantly, we observed that MT reshapes the gut microbiome of newborns by altering the abundance and interaction of Bacteroides species, as well as amino acid pathways, such as arginine biosynthesis. Two-year follow-up of those calves further showed that MT improves their later milk production. Notably, MT improves fiber digestion and antioxidant capacity of newborns while reducing diarrhea. MT also contributes to significant changes in the metabolomic landscape, and with putative causal mediation analysis, we suggest that altered gut microbial composition in newborns may influence physiological status through microbial-derived metabolites. CONCLUSIONS:Our study provides a metagenomic and metabolomic atlas of the temporal development of the gut microbiome in newborn calves. MT can alter the gut microbiome of newborns, leading to improved physiological status and later milk production. The data may help develop strategies to manipulate the gut microbiota during early life, which may be relevant to the health and production of newborn calves.

本试验对不同含水量及原料组合对薯渣混贮效果的影响进行研究,并筛选出适宜薯渣混贮的最佳组合.采用双因素试验设计,用塑料桶将薯渣与棉籽粕和/或菜籽粕[(薯渣+菜籽粕(鲜重比例为1∶1,SC)组合、薯渣+棉籽粕(鲜重比例为1∶1,SM)组合、薯渣+菜籽粕+棉籽粕(鲜重比例为2∶1∶1,SCM)组合]按重量比混合并搅拌均匀,并调节含水量分别为45％、50％、55％.将混合后的具有不同含水量的混贮原料分别装入5 L密封塑料桶并压实,进行混贮发酵,共9个处理,每个处理3个重复.室温条件下贮藏70 d后用四分法进行取样,进行样品发酵品质、营养品质、营养物质瘤胃降解率(48 h)以及有氧稳定性的测定.结果显示:低含水量(45％)条件下SC组合的pH、氨态氮/总氮(AN/TN)最低,乳酸(LA)含量最高,且各处理均未检测到丁酸(BA);低含水量(45％)条件下SC组合混贮后较其他组合显著或极显著降低了中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)的含量(P＜0.05或P＜0.01),极显著提高了淀粉的含量(P＜0.01);在有氧暴露12 d内各处理均未发生有氧腐败,有氧稳定性时间均超过240 h;低含水量(45％)条件下SC组合的干物质(DM)、粗蛋白质(CP)、NDF、ADF和淀粉的瘤胃降解率(48 h)均为最高.综上所述,从营养品质、发酵品质以及营养物质瘤胃降解率综合来看,以低含水量(45％)条件下以薯渣与菜籽粕按照鲜重1∶1的比例混贮效果较好.

Chromium propionate (CrP) supplementation has the potential effects on mitigating metabolic stress on dairy cows, however, the effect of increased CrP supply on alleviating heat stress of mid-lactation cows is rarely evaluated. This study was conducted to evaluate the effect of CrP sup-plementation on lactation performance, nutrient digestibility, rumen fermentation patterns, and antioxidant status in dairy cows under heat stress. Sixty-four Holstein dairy cows in mid-lactation with similar parity (2.1 +/- 0.2), current milk production (40 +/- 1.4 kg/d), and days in milk (143 +/- 7.8 d) were randomly allocated to one of four treatments with a completely randomized design. After a 7-day adaptation period, cows were fed CrP at doses of 0, 4, 8, and 12 mg/d of Cr per head for 49 d. The average temperature humidity index (THI) was 77 during the experimental period. The average respiration rate and rectal temperature decreased quadratically (P < 0.01) with increasing CrP supplementation. Dry matter intake (DMI), milk yield, and milk lactose yield increased quadratically (P < 0.05) with increasing CrP supplementation, whereas 4% fat-corrected milk was not affected by treatments, and feed efficiency tended to decrease quadrati-cally (P = 0.07). The percentage of milk protein and lactose increased linearly (P = 0.05) with increasing CrP supplementation, whereas milk urea-N concentration and somatic cell count decreased quadratically (P < 0.01). Although total-tract apparent digestibility of dry matter, organic matter, crude protein, and ether extract was not affected by CrP supplementation, neutral detergent fiber digestibility increased quadratically (P = 0.01) with increasing CrP supplemen-tation. The concentrations of milk Cr and urinary Cr were not affected by CrP supplementation. Ruminal pH, the concentration of total VFA and ammonia-N, and the molar proportion of pro-pionate and butyrate were not affected by treatments, whereas the molar proportion of acetate increased quadratically (P < 0.01) with increasing CrP supplementation. The blood urea-N concentration decreased quadratically (P < 0.01) and the concentration of glutathione peroxidase and superoxide dismutase increased quadratically (P < 0.01) with increasing CrP supplementation, while the ratio of glucose to insulin and the concentration of glucose and malonaldehyde did not differ among treatments. In conclusion, CrP supplementation could increase milk yield in mid-lactation cows under heat stress by increasing DMI, reducing respiration rate and rectal temperature, and improving antioxidant status. The recommended dose of CrP is 4-8 mg/d of Cr per cow in hot weather.

Jujube has a sweet taste and rich nutritional value, which can be used as unconventional feed in animal production. However, the water content of jujube fresh fruit is high, so it needs to be treated before it can be used as diet. Jujube powder feed is one of the ways to improve the utilization effect of jujube. The paper mainly summarizes the present situation of jujube resources, nutritional composition of jujube, types of jujube meal feed and its application and problems in animal production in China, to provide reference for the application of jujube meal as unconventional feed in animal production.

【Objective】The purpose of this experiment was to explore the effects of different proportions of mixed silage of raw potato chips processing by product with rice straw（hereinafter referred to as “mixed storage”） instead of whole plant corn silage（hereinafter referred to as “silage”） on fattening performance, nutrient apparent digestibility, rumen fermentation parameters, blood biochemical indexes and economic benefits of Holstein bulls, so as to provide a theoretical basis for the use of potato processing by-products in cattle production.【Method】Sixty healthy Holstein bulls with similar body weight（（461.33 ± 33.47） kg） were randomly divided into four groups with 15 replicates in each group and one bull per replicate, including T20 group（concentrate +20% mixed silage + 80% silage）, T40 group（concentrate + 40% mixed silage + 60% silage）, T60 group（concentrate + 60% mixed silage + 40% silage）, and T80 group（concentrate + 80% mixed silage + 20% silage）. The ratio of concentrate to roughage and the composition of concentrate were the same in the experimental group. Adaptation and experimental periods lasted for 10 and 150 d,respectively.【Result】（1） there was no significant difference in average daily gain（ADG） of Holstein bulls with different proportions of mixed silage instead of whole plant maize silage（P＞0.05）. The dry matter intake（DMI） of T20 group was 4.30% higher than that of T40 group（P＜0.01）, 5.24% higher than that of T60 group（P＜0.01）, and 6.01% higher than that of T80 group（P＜0.01）. The feed gain ratio（F/G） of T40 group was the lowest, which was 4.08%（P＜0.01）, 3.14%（P＜0.05）, and 5.60%（P＜0.01） lower than that of T20, T60, and T80 groups, respectively.（2） Compared with T80 group, the apparent digestibility of dry matter（DM）, neutral detergent fiber（NDF）, acid detergent fiber（ADF） and ether extract（EE） of the first three groups were significantly increased（P＜0.05）. The apparent digestibility of crude protein（CP） of T20 group was significantly higher than that of T60 and T80 groups（P＜0.05）, but there was no significant difference between T20 group and T40 group（P＞0.05）.（3） The rumen pH, propionic acid and butyric acid contents were not affected by increasing the proportion of mixed storage（P＞0.05）. However, the concentrations of ammonia nitrogen（NH3-N） and total volatile fatty acids（TVFA） of T60 and T80 groups were significantly lower than those of T20group（P＜0.05）, and the content of acetic acid was significantly higher than that of T20 group（P＜0.01）. The ratio of acetic acid to propionic acid of T80 group was significantly higher than that of T20 and T40 groups（P＜0.05）.（4） Albumin（ALB） content of T20group was significantly higher than that of T60 and T80 groups（P＜0.05）. Urea nitrogen（UN） concentration of T80 group was significantly increased（P＜0.01）, 29.05%, 20.96% and 11.31% higher than that of T20, T40 and T60 groups, respectively. Glucose（Glu） concentration of T20 group was significantly higher than that of T60 and T80 groups（P＜0.01）, and there was no significant difference between T20 group and T40 group（P＞0.05）.（5） The economic benefit of T40 group was the highest（17.96yuan·head-1·d-1）, followed by T20（16.91 yuan·head-1·d-1）, T60（16.79 yuan·head-1·d-1） and T80（15.91 yuan·head-1·d-1）.【Conclusion】In conclusion, with the increase of the proportion of mixed silage instead of silage, the digestibility of nutrients,rumen fermentation and blood biochemical indexes would be affected to some extent. When replacing 40% whole plant maize silage,the production performance was the best and the economic benefit was the highest.

红枣口味甘甜,营养价值丰富,可作为非常规饲料在动物生产中应用.但是红枣鲜果的含水量较高,需要进行一定处理才可作为饲粮使用.制作成枣粉饲料是提高红枣利用效果的方式之一.文章主要综述了我国红枣资源现状、红枣的营养成分、枣粉饲料的种类及其在动物生产中的应用和问题,为枣粉作为非常规饲料在动物生产中的应用提供参考.

This experiment was conducted to study the effects of different treatment time and supplemental level of cellulase on in vitro nutrient degradation rate and rumen fermentation characteristics of wheat straw. A 4×4two-factor experimental design was used,including four cellulase treatment time（0,15,30 and 720 min）and four cellulase supplemental level（5 000,10 000,15 000 and 20 000 U/kg）,and the nutrient degradation rate and fermentation parameters were determined at different fermentation time（24 and 48 h）. The results showed as follows:1)with the cellulase treatment time increased,the in vitro fermentation dry matter degradation rate（DMD）,neutral detergent fiber degradation rate（NDFD）,acid detergent fiber degradation rate（ADFD）,acid detergent lignin degradation rate（ADLD）,hemicellulose degradation rate（HD）and cellulose degradation rate（CD）at 24 and 48 h were significantly increased（P＜0.05）except the HD at 24 h. With the cellulase supplemental level increased,the DMD,NDFD,ADFD,HD and CD at 24 h and HD at 48 h were linearly increased（P＜0.05）,and the ADLD at 24 h and DMD,NDFD,ADFD,ADLD and CD at 48 h were quadratically increased（P＜0.05）. There were no significant differences DMD,NDFD,ADFD,ADLD and CD between 10 000 and 20 000 U/kg cellulase supplemental level（P＞0.05）. 2)With the cellulase treatment time increased,the in vitro fermentation ammoniacal nitrogen（NH3-N）concentration was significantly increased（P＜0.05）,but the cellulase supplemental level had no significant effect on in vitro fermentation NH3-N concentration（P＞0.05）. With the cellulase treatment time increased,the in vitro fermentation total volatile fatty acid（TVFA）concentration at 48 h was significantly increased（P＜0.05）. 3)The 48 h gas production of30 min treatment time was significantly higher than that of other treatment time（P＜0.05）,and the theoretical maximum gas production and gas production rate of 30 and 720 min were significantly higher than those at0 min（P＜0.05）. With the cellulase supplemental level increased,the 48 h gas production,theoretical maximum gas production and gas production rate were quadratically increased（P＜0.05）. In conclusion,when cellulase supplemental level is 10 000 U/kg and treatment time is 30 min,it can improve the in vitro nutrient degradation rate of wheat straw,increase the NH3-H and VFA concentrations,improve gas production and gas production parameters,and improve in vitro rumen fermentation.[Chinese Journal of Animal Nutrition,2023,35（4）:2431-2442]

The aim of this study was to investigate the effect of low-protein diets supplemented with rumen-protected lysine (RPLys) and methionine (RPMet) on growth performance, rumen fermentation, blood biochemical parameters, nitrogen metabolism, and gene expression related to N metabolism in the liver of Holstein bulls. Thirty-six healthy and disease-free Holstein bulls with a similar body weight (BW) (424 ± 15 kg, 13 months old) were selected. According to their BW, they were randomly divided into three groups with 12 bulls in each group in a completely randomized design. The control group (D1) was fed with a high-protein basal diet (CP13%), while bulls in two low-protein groups were supplied a diet with 11% crude protein and RPLys 34 g/d·head + RPMet 2 g/d·head (low protein with low RPAA, T2) or RPLys 55 g/d·head + RPMet 9 g/d·head (low protein with high RPAA, T3). At the end of the experiment, the feces and urine of dairy bulls were collected for three consecutive days. Blood and rumen fluid were collected before morning feeding, and liver samples were collected after slaughtering. The results showed that the average daily gain (ADG) of bulls in the T3 group was higher than those in D1 (p < 0.05). Compared with D1, a significantly higher nitrogen utilization rate (p < 0.05) and serum IGF-1 content (p < 0.05) were observed in both T2 and T3 groups; however, blood urea nitrogen (BUN) content was significantly lower in the T2 and T3 groups (p < 0.05). The content of acetic acid in the rumen of the T3 group was significantly higher than that of the D1 group. No significant differences were observed among the different groups (p > 0.05) in relation to the alpha diversity. Compared with D1, the relative abundance of Christensenellaceae_R-7_group in T3 was higher (p < 0.05), while that of Prevotellaceae _YAB2003_group and Succinivibrio were lower (p < 0.05). Compared with D1 and T2 group, the T3 group showed an expression of messenger ribonucleic acid (mRNA) that is associated with (CPS-1, ASS1, OTC, ARG) and (N-AGS, S6K1, eIF4B, mTORC1) in liver; moreover, the T3 group was significantly enhanced (p < 0.05). Overall, our results indicated that low dietary protein (11%) levels added with RPAA (RPLys 55 g/d +RPMet 9 g/d) can benefit the growth performance of Holstein bulls by reducing nitrogen excretion and enhancing nitrogen efficiency in the liver.

为研究脂肪来源对围产后期奶牛生产性能、瘤胃发酵、血液参数的影响,本试验选取胎次[(2.95±0.1)胎]、体况和上一胎次平均产奶量[(31.4±0.4)kg]相近的健康中国荷斯坦奶牛60头,采用完全随机试验设计,分为三组,每组20头奶牛,分别饲喂泌乳净能和粗蛋白质含量一致,但脂肪(酸)来源不同的日粮,三组分别为基础饲粮组(A组)、脂肪酸钙组(B组)、棕榈酸脂肪粉组(C组).试验期为母牛分娩当天(0 d)至产后21 d.试验结果表明:(1)干物质采食量:除泌乳天数10～12 d干物质采食量,B组较其他两组有下降的趋势(P=0.06)外,其他各阶段B组奶牛的干物质采食量显著低于A组和C组(P＜0.05),全期干物质采食量B组较A组和C组下降18.78％和14.56％(P＜0.01).(2)产奶量方面:整个试验期,B组产奶量均低于A组和C组(P＜0.05),但A组和C组差异不显著(P＞0.05),全期产奶量B组较A组和C组下降13.41％和12.48％(P＜0.05).(3)瘤胃发酵参数方面:血液β-羟丁酸浓度(BHBA)在产后7、14 d差异不显著(P＞0.05),产后21 dC组奶牛血液BHBA浓度较A组和B组下降16.44％和25.96％(P＜0.05),A组和B组差异不显著(P＞0.05);血液非酯化脂肪酸(NEEF)浓度在产后7 d和14 d差异不显著(P＞0.05),而在产后21 d C组较A组和B组下降31.49％和31.06％(P＜0.05);总胆固醇(TC)、甘油三脂(TG)、葡萄糖(GLU)、胰岛素生长因子(IGF-1)、牛瘦素(Lep)、尿素氮(BUN)检测产后0、7、14、21d组间差异不显著(P＞0.05).(4)血液肝脏指标代谢方面:在肝损代谢中谷丙转氨酶和谷草转氨酶虽然在产后0、7、21 d差异不显著(P＞0.05),但是产后14 d谷丙转氨酶C组较A组和B组下降28.98％和35.32％(P＜0.05),谷草转氨酶下降28.66％和10.62％(P＜0.05).A组和B组差异不显著.碱性磷酸酶、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇产后0、7、14、21天差异不显著(P＞0.05).综上所述,在本试验条件下,饲粮中添加脂肪粉可提高围产后期奶牛采食量和产奶量,缓解奶牛体脂动员程度,提高血清GLU浓度,降低NEFA和BHBA浓度,缓解奶牛能量负平衡(NEB),并且效果好于脂肪酸钙组.

试验旨在探讨霉菌毒素吸附剂对西门塔尔育肥牛瘤胃发酵指标及微生物区系的影响.选择健康、体况良好、平均体重为365.64 kg的西门塔尔育肥牛32头,随机分为2组,每组16个重复,每个重复1头牛.对照组牛饲喂基础日粮,处理组在基础日粮中添加0.2 g/kg霉菌毒素吸附剂.预试期7 d,正式试验期193 d,霉菌毒素吸附剂在晨饲时投喂.结果显示,与对照组相比,处理组西门塔尔育肥牛瘤胃菌体蛋白(MCP)含量显著提高(P<0.05),瘤胃的Simpson指数具有升高的趋势(P>0.05),棒状菌门的丰度具有降低的趋势(P>0.05).研究表明,添加0.2 g/kg霉菌毒素吸附剂具有促进西门塔尔育肥牛瘤胃微生物对氮的利用、丰富微生物区系的物种多样性和降低棒状菌门相对丰度的趋势.

The experiment was to investigate the effect of supplementing leucine and tryptophan in low protein diets on growth performance, serum biochemical indicators, immune performance, and antioxidant capacity of weaned calves. Chinese Holstein calves with good health and similar birth weight (42±2) kg were randomly divided into five groups. The groups were HK group (22% CP level of open food), LK group (19% CP level of open food), L group (19% CP level containing 1.15% Leu of open food), T group (19% CP level of 0.26% Trp of open food), LT group (19% CP level of 1.15% Leu+ 0.26% Trp of open food). There were 12 replicates in each group with one calve in each replicate. The experiment lasted for 72 d. The results showed that final weight, average daily feed intake and average daily gain in LT group were higher than HK group (P<0.05). Three days before weaning, the content of BUN and IL-1 were lower than HK group (P<0.05). While the content of TP, IgM, interferon-γ, superoxide dismutase and catalase activities were significantly increased in LT group (P<0.05). On the day of weaning, compared with HK group, the activity of TP, IgA, IL-2 and T-AOC significantly increased (P<0.05). On the third day after weaning, the content of TNF-α was significantly increased in LT group (P<0.05). The experiment indicates that supplementation of Leu (1.15%) and Trp (0.26%) in low protein diet increased average daily gain and average daily feed intake of weaned calves, improve calf growth performance, enhanced immunity and oxidation ability of weaned calves, and alleviated weaning stress.

The study was conducted to evaluate the effect of replacing dietary corn silage (CS) and alfalfa hay (AH) with millet straw (MS) on the production performance and the ruminal fermentation patterns of Holstein cows in late lactation. For this purpose, forty-eight multiparous Holstein dairy cows blocked by milk yield (32 +/- 3.2 kg/d) and days in milk (179 +/- 19 d) were randomly allocated to one of four treatments. The diets were formulated with a forage-to-concentrate ratio of 48:52 [dry matter (DM) basis] and contained the same concentrate mixtures, with different forage sources (on a DM basis): (1) Control (60% CS, 40% AH, and 0% MS; on 100% roughage); (2) LMS (54% CS, 36% AH, and 10% MS), (3) MMS (48% CS, 32% AH, and 20% MS), and (4) HMS (42% CS, 28% AH, and 30% MS). The dry matter intake and milk yield were lower in the HMS diet than those in the Control, LMS, and MMS diets (P < 0.01), whereas there was no difference in the Control, LMS, and MMS diets. Compared with the Control diet, 4% FCM, milk protein yield, and N conversion ratio decreased in the MMS and HMS diets (P < 0.01), whereas no difference between the Control and LMS diets was found. Besides, cows fed the HMS diet had lower milk fat yield, lactose percentage, and feed efficiency than those in the Control and LMS diets (P < 0.05), with no difference between the Control, LMS, and MMS diets. The percentage of milk fat and protein was not affected by the diets. Compared with the Control diet, the total VFA concentration was decreased, whereas the ammonia-N concentration was increased in the HMS diet (P < 0.05), with no difference between the Control, LMS, and MMS diets. The molar proportion of acetate and the ratio of acetate to propionate were lower (P < 0.01), while the molar proportion of propionate was higher in the Control diet than that in the MMS and HMS diets (P < 0.01), with no difference between the LMS and MMS diets. Compared with the Control, the apparent digestibility of DM, CP, NDF, and ADF was decreased, while the blood urea nitrogen concentration was increased in the HMS diet (P < 0.05), with no differences in the Control, LMS, and MMS diets. Thus, it was concluded that it is feasible to use MS as a fiber source for latelactation dairy cows. However, considering the milk production performance and the feed digestibility, the replacement of CS and AH with MS should not exceed 20% of the roughage.

研究旨在评价不同原料和含水量对薯渣混贮发酵效果的影响,并筛选出适宜的含水量和混贮组合.采用双因素完全随机试验设计,将薯渣与玉米皮(SY)、薯渣与大豆皮(SD)、薯渣与玉米皮和大豆皮(SYD,薯渣与能量饲料比例为1:2,玉米皮与大豆皮鲜重比例为1:1)进行发酵,设置低、中、高水分含量(45％、55％、65％),80 d后测定发酵品质、营养品质及48 h瘤胃降解率及有氧稳定性.结果表明:从感官评定、营养品质、发酵品质来看,中水分(55％)SY组感官品质最佳,pH、氨态氮/总氮(AN/TN)较低,乳酸(LA)含量较高,粗蛋白质(CP)含量极显著增加(P<0.01),中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)含量极显著降低(P<0.01),淀粉营养物质的保存量提高,且各组均未检测到丁酸(BA).从有氧稳定性来看,各组均未发生有氧腐败,有氧稳定性时间均超过360 h.中水分(55％)SD组48 h干物质(DM)瘤胃降解率及NDF、ADF降解率较高.从感官评定、营养品质、发酵品质来看,以薯渣与玉米皮混贮品质最佳,薯渣与玉米皮和/或大豆皮混合青贮时以含水量为55％时品质较好;从营养物质瘤胃降解率看以薯渣与大豆皮混贮品质最佳.

试验采用体外产气法研究不同日粮30 h中性洗涤纤维(dNDF30)水平对反刍动物瘤胃发酵的影响.在等能等氮(蛋白含量为16.5％)与中性洗涤纤维(NDF)水平为32％下分别配制dNDF30水平为16.4％、17.9％、19.4％、20.9％、22.4％、23.9％、25.4％和26.9％的日粮为发酵底物,分别为T1组～T8组,每组8个重复.结果显示,体外发酵24 h,T1组的产气量(GP)显著低于其他各组(P<0.05).体外发酵48 h,T5组、T6组、T7组、T8组GP显著高于其他处理组(P<0.05).T8组的体外干物质消失率(IVDMD)最高,显著高于T1组、T2组、T3组、T4组(P<0.05).T8组pH值显著低于其他各组(P<0.05).T1组氨态氮(NH3-N)含量显著高于除T2外的各组(P<0.05).T1组微生物蛋白(MCP)含量显著高于其他各组(P<0.05).T8组总挥发性脂肪酸含量最高,显著高于除T7组、T6组之外的各组(P<0.05).T1组乙酸含量显著高于除T2组、T3组、T4组外各组(P<0.05).T8组丙酸含量显著高于T1组、T2组(P<0.05).研究表明,较高日粮dNDF30水平有利于氨氮的利用和反刍动物瘤胃发酵.

This experiment was conducted to investigate the effects of N-carbamylglutamate（NCG） supplementation in different doses on microflora composition in rumen and rectum of Holstein bulls. Forty-five healthy Holstein bulls [initial body weight（478±13.66） kg, 12 to 13 months of age] were randomly divided into three groups, and there were 15 bulls in each group, 0（group Ⅰ）, 15（group Ⅱ） and 25 g/（d·bull） NCG（group Ⅲ） were added in a basal diet, respectively. The pre-test period lasted for 7 days and the experimental period lasted for 90 days. Results showed as follows: with the increase of NCG supplemental dose, rumen microbial diversity was not significantly affected（P＞0.05）, but the relative abundance of Bacteroidetes showed linear decreasing trend（0.05＜P＜0.10）, while the relative abundance of Firmicutes showed linear increasing trend（0.05＜P＜0.10）. At genus level, the relative abundance of Ruminococcus 1 in group Ⅱ was significantly higher than that in group Ⅰ（P＜0.05）. The relative abundance of Ruminococcaceae UCG-005 showed increasing trend（P=0.05）, and the relative abundance of Succinivibrio showed linear increasing with the increase of NCG supplemental dose（P＜0.05）, and the relative abundance of Lachnospiraceae 2 showed linear increasing trend with the increase of NCG supplemental dose（0.05＜P＜0.10）. In the rectal microflora, the diversity of rectal microflora showed liner increasing trend with the increase of NCG supplemental dose（P＞0.05）. At phylum level, the supplement of NCG had no significant effect on rectal microflora（P＞0.05）, but the relative abundance of Patescibacteria showed quadratic curve change with the increase of NCG dose（0.05＜P＜0.10）. At genus level, the relative abundance of Rikenellaceae RC9 gut group showed liner increasing trend with doses the increase of NCG（0.05＜P＜0.10）, the relative abundance of Bifidobacterium and Ruminococcaceae UCG-010 in group Ⅱ was significantly higher than that in group Ⅰ（P＜0.05）, and there was no significant difference compared with group Ⅲ（P＞0.05）. In conclusion, the addition of NCG does not significantly increase the relative abundance of microorganisms in rumen and rectum except for Rumenococcus 1 at rumen genus level and Bifidobacterium and Ruminococcaceae UCG-010 at rectum genus level.

为了探究稻草与全株玉米青贮比例和发酵菌剂在混合饲粮中的组合效应,采用双因子完全随机试验设计,将不同稻草与全株玉米青贮比例(100∶0、80∶20、60∶40、40∶60、20∶80、0∶100)和发酵菌剂(未添加发酵菌剂、添加发酵菌剂)的混合饲粮进行体外发酵,测定常规发酵指标并进行隶属函数分析.结果表明:①稻草与全株玉米青贮的比例对产气量(GP)有显著影响(P<0.05),随着稻草比例的减少,GP总体上呈上升趋势;添加发酵菌剂对GP有显著影响(P<0.05);稻草添加比例和发酵菌剂的互作效应在8、36、48 h影响显著(P<0.05).②稻草与全株玉米青贮的比例对干物质降解率(DMD)有显著影响(P<0.05).③稻草与全株玉米青贮的比例以及添加发酵菌剂对pH均有显著影响(P<0.05),pH范围为6.85～7.12.④添加发酵菌剂显著降低了稻草与全株玉米青贮的比例为80∶20和20∶80时的氨态氮(NH3-N).⑤稻草与全株玉米青贮的比例对丙酸(PA)、丁酸(BA)和乙/丙(AA/PA)有显著影响(P<0.05),添加发酵菌剂对乙酸(AA)、丙酸、总挥发性脂肪酸(T-VFA)有显著影响(P<0.05),稻草添加比例和添加发酵菌剂对乙/丙的互作效应显著(P<0.05).隶属函数分析表明,当稻草与全株玉米青贮比例为40∶60、20∶80、0∶100时无论是否添加发酵菌剂,发酵效果均优于稻草与全株玉米青贮比例为100∶0、80∶20、60∶40时,其中稻草与全株玉米青贮的比例在20∶80时发酵效果更好;当稻草与全株玉米青贮比例为40∶60、20∶80、0∶100时可不添加发酵菌剂,以降低成本.

ABSTRACT The rumen of neonatal calves is not well-developed and exhibits limited functionality. Therefore, the establishment of intestinal microbiota may play an instrumental role in their health and performance, but it has been rarely explored. Thus, we aim to explore the temporal colonization of the gut microbiome and the potential benefits of early microbial intervention in newborn calves. We followed up on the temporal dynamics of the gut microbiome and plasma metabolome in 36 newborn calves during the first two months of life and established their relationships with their health status and performance. We also evaluated whether microbiota transplantation (MT) could influence their phenotypes by modulating metabolism and its impact on later milk production performance.We showed that the composition and ecological interactions of the gut microbiome are likely to reach maturity one month after birth. Temporal changes in the gut microbiome of newborn calves are widely associated with changes in their physiological statuses, such as growth and fiber digestion. Importantly, we observed that MT reshapes the gut microbiome of newborns by altering the abundance and interaction of Bacteroides species, as well as amino acid pathways, such as arginine biosynthesis. Two-year follow-up of those calves further showed that MT improves their later milk production. Notably, MT improves fiber digestion, antioxidant capacity of newborns while reducing diarrhea. MT also contributes to significant changes in the metabolomic landscape, and with putative causal mediation analysis, we suggest that altered gut microbial composition in newborns may influence physiological status through microbial-derived metabolites. The data from the study may help develop strategies to manipulate the gut microbiota during early life, which may be significantly relevant to the health and production of newborn calves. HIGHLIGHTS The gut microbial composition and ecological interaction in newborn calves reach maturity one month after birth Temporal shifts in the gut microbiome of newborn calves are associated with phenotypic changes, including growth, digestion, and antioxidative capacity Early microbial intervention in newborn calves reduces diarrhea while improving later milk production The gut microbial impact on newborn calves is mediated by plasma metabolites