In situ provision of drinking water to grazing dairy cows improves milk production

AIMS: To determine the effect of providing water within the area grazed by dairy cows on milk yield and quality, compared to requiring cows to walk to a distant water trough, on a dairy farm in the Pampa region of Argentina during summer.

METHODS: Holstein dairy cows were allocated to two herds with similar parity, days in milk and milk production. They were grazed in one paddock that was divided in two, with a fixed water trough at one end. Cows were moved twice daily to grazing plots within the paddock. Control cows (n=66) could only access water from the fixed trough, whereas supplemented cows (n=67) also received water from a mobile trough within the grazing plot. Milk production of each cow, and water consumption of the two herds were measured daily over 62 days. Milk composition for each herd was determined weekly from Days 18 to 60 of the study, and grazing behaviour was observed between 08:00 and 16:00 hours on Days 11–15, 19–22 and 39–43.

RESULTS: Over the 62 days of the study, supplemented cows produced 1.39 (SE 0.11) L/cow/day more milk than Control cows (p=0.027). Estimated mean daily water intake was 50.4 (SE 2.1) L/cow/day for supplemented cows and 58.2 (SE 2.7) L/cow/day for Control cows (p=0.004). Percentage total solids in milk was higher for supplemented (12.5 (SE 0.06)%) than Control (12.4 (SE 0.04)%) cows (p=0.047). During the periods of behavioural observation, a higher percentage of cows in the water supplemented than the Control herd were observed in the grazing area (p=0.012).

CONCLUSIONS AND CLINICAL RELEVANCE: This preliminary study demonstrated that provision of water to dairy cows within the grazing plot was beneficial for milk production and composition, and may be associated with longer periods spent within the grazing area, during hot weather in the Pampa region of Argentina.     

Restricting access time at pasture and time of grazing allocation for Holstein dairy cows: Ingestive behaviour,dry matter intake and milk production

The objective of this study was to assess the effects of restricting access time to pasture and time of grazing allocation on grazing behaviour, daily dry matter intake (DMI), rumen fermentation, milk production and composition in dairy cows. Twenty-one autumn-calving Holstein cows were assigned to one of the following 3 treatments: providing access to a daily strip of pasture for either 8 h between 07:00 and 15:00 h (T7–15), 4 h between 07:00 and 11:00 h (T7–11), or 4 h between 11:00 and 15:00 h (T11–15). The experimental period consisted of 3 weeks of adaptation and 6 weeks of measurements. Cows were offered a daily herbage allowance of 18 kg DM/cow to ground level, 6.1 kg DM/day of a ground sorghum grain-based supplement and 5.2 kg DM/day of maize silage. Milk yield was greater for cows with 8 h access time to the pasture (25.4 vs. 24.1 for 8 and 4 h access time, respectively). Milk yield was not different between cows that access early (T7–11) or late (T11–15) to the grazing session. Milk protein yield was greater for cows with 8 h access time (0.75 kg/d) vs. 4 h access time treatments (0.72 kg/d). Cows with late access time to grazing in the morning produce more protein (0.74 kg/d) than cows with early access to the pasture (0.70 kg/d). Duration of access had a significant effect on herbage DMI (8.3 vs. 6.6 kg/d, for 8 and 4 h access, respectively), but there was no significant effect of time of grazing allocation. Intakes of concentrate and maize silage DM did not differ between treatments.     

奶牛放牧对北方农牧交错带人工草地植被的影响

研究了不同处理奶牛放牧对混播人工草地植被的影响。结果表明,牧草现存量随着放牧强度的增加而降低,轻牧比中牧高7.28%,且轮牧高于连续放牧1.99%,轮牧对紫花苜蓿和无芒雀麦的再生有利。随放牧强度增加,紫花苜蓿和无芒雀麦重要值下降,蓝茎冰草和新麦草增加。放牧对牧草的茎叶比有显著影响,放牧后4种牧草的茎叶比均有下降,连续放牧高于轮牧。根系主要集中在土壤表层0~10 cm,约占0~30 cm总量的70%,且其生物量也以轮牧制较高,随放牧强度的增加而下降。     

Plasma cholesterol levels and short-term adaptations of metabolism and milk production during feed restriction in early lactating dairy cows on pasture

Low plasma total cholesterol (TC) concentrations are characteristic during the negative energy balance in early lactating dairy cows. The objective was to investigate short-term effects of different TC concentrations during an aggravated energy deficiency through a 1-week concentrate withdrawal on adaptations of metabolism and milk production. Multiparous Holstein cows (n = 15) were investigated during 3 week beginning at 24 ± 7 DIM (mean ± SD). Cows were kept on pasture and received additional concentrate in experimental week 1 and 3, while in week 2, concentrate was withdrawn. Blood was sampled once and milk twice daily. Based on their average TC concentration during week 1 (prior to concentrate withdrawal), cows were retrospectively assigned into a high (H-Chol; n = 8, TC ≥ 3.36 mmol/L) and a low TC groups (L-Chol; n = 7, TC < 3.36 mmol/L). Concentrations of phospholipids and lipoproteins were higher in H-Chol compared to L-Chol throughout the study (p < 0.05). During concentrate withdrawal, milk yield, glucose and insulin concentrations decreased similarly in both groups, while milk fat, milk acetone and plasma BHB were higher in H-Chol compared to L-Chol (p < 0.05). Compared to initial values, plasma NEFA, TAG and VLDL increased in both groups within 2 days after concentrate withdrawal (p < 0.05). Concentrations of NEFA during week 2 were greater in L-Chol compared to H-Chol (p < 0.05). Despite reintroduction of concentrate, milk yield in H-Chol remained lower for two more days compared to week 1 (p < .05), whereas milk yield recovered immediately in L-Chol. Activity of aspartate aminotransferase was higher in H-Chol compared to L-Chol in week 2 (p < 0.05). Greater plasma TC concentrations were associated with a reduced increase of NEFA. Further research is warranted if TC concentrations are related to adipose tissue mobilization and fatty acid turnover.     

不同微生态制剂对奶牛产奶性能和乳品质的影响

[目的]研究旨在探讨不同微生态制剂对奶牛产奶性能和乳品质的影响,[方法]将40头荷斯坦奶牛随机分成4个处理组,对照组饲喂基础日粮,微生态制剂1组、微生态制剂2组、微生态制剂3组分别在基础日粮中添加0.1%的三种微生态制剂产品。[结果]结果显示：与对照组相比,微生态制剂1组、微生态制剂2组、微生态制剂3组的平均日产奶量、乳蛋白率均显著增加（P＜0.05）,体细胞数均显著降低（P＜0.05）。与对照组相比,微生态制剂1组的平均日采食量、乳脂率均显著增加（P＜0.05）,料奶比显著降低（P＜0.05）。与微生态制剂2组相比,微生态制剂1组的平均日产奶量、乳蛋白率均显著增加（P＜0.05）。[结论]说明三种微生态制剂产品均能在一定程度上提高奶牛的产奶性能和乳品质,以微生态制剂产品1的作用效果最好。     

Effects of supplementary corn silage on the feed intake and milk production of time-restricted grazing dairy cows

The effects of supplementary corn silage (CS) of either 2 or 4 kg of dry matter (DM; S + 2 and S + 4, respectively) above the energy requirement for milk production and maintenance for grazing dairy cows (S) were determined. Time‐restricted grazing was used to compare the feed intake, milk production, and nitrogen and energy use of lactating cows. The experiment was carried out on two different pastures using a 3 × 3 Latin square design for each pasture. Cows were grazed for 5 h on a rotational grazing system and were fed concentrate (1 kg per 5 kg of milk yield). Herbage intake was measured using a weighing technique. To calculate the energy and nitrogen use, whole feces and urine were collected. There was no statistical effect of the pastures. Herbage intake decreased by the addition of CS (P = 0.02). The reduction of herbage DM intake per unit consumption of supplementary CS towards the S group were 0.80 and 0.45 kg for the S + 2 and S + 4 groups, respectively. The total DM intake for the S + 4 group was higher than that for the S and S + 2 groups (P = 0.02). Milk yield did not differ among treatments, even though the total DM intake for the S + 4 group was higher than that of the S and S + 2 groups. Nitrogen and energy use did not differ with the addition of CS.     

Effects of grazing adaptation on herbage intake,milk production,and body weight change in lactating dairy cows after turning out to pasture in early spring

The present study investigated the effects of adaptation to grazing in early spring on the herbage intake, milk production, and body weight changes in lactating dairy cows. The experiment included 12 Holstein lactating cows during early spring. Six cows were allowed to gradually adapt to grazing (ADP) over 10 days. They were allowed to graze on a pasture for 4 h during the first week and for 19 h during the remaining 3 days (adaptation period). During the 10-day period, the remaining six cows were housed in a barn (CON). Cows in both groups received adequate silage, hay, and concentrate during the adaptation period. Subsequently, cows in both groups were allowed to graze together for 19 h for 4 weeks (experimental period). No cow received supplements during the experimental period. In the first week of the experimental period, the ADP cows showed a higher herbage intake than the CON cows. During the subsequent weeks, there were no differences in herbage intake between the two groups. At the start of the experimental period, milk production and body weight of the ADP cows were higher than those of the CON cows, and this difference lasted until the end of the experiment.     

过瘤胃氨基酸高能复合物对奶牛产奶量及乳成分的影响

为研究不同过瘤胃氨基酸高能复合物对奶牛产奶量及乳成分的影响,试验选择胎次(3～5胎)、产奶量、产犊日期相近,体重(600±20)kg健康荷斯坦泌乳高峰期奶牛24头,随机分为4组,每组6头。1组为对照组,饲喂牛场常规日粮;2、3、4组为试验组,分别在常规日粮基础上添加过瘤胃氨基酸高能复合物Ⅰ、Ⅱ、Ⅲ500 g/(d.头)。正式期60 d。结果表明:奶牛日粮中添加过瘤胃氨基酸高能复合物后,均可明显提高奶牛产奶量、乳脂率、乳蛋白率及乳中总干物质含量。尤其是复合物Ⅲ,添加效果最为理想,平均日产奶量、乳脂率、乳蛋白率及总干物质含量分别比对照组提高21.19%(P<0.05)、21.31%(P<0.05)、9.72%(P<0.05)和10.34%(P<0.05),平均日校正乳产量提高35.70%(P<0.05)。     

Relationship between feeding behaviour and feed intake of dairy cows depending on their parity and milk yield

To investigate the relationship between the parameters of feeding behaviour and feed intake, 70 lactating dairy cows (23 primiparous and 47 multiparous) were monitored from the 2nd to 15th week of lactation. Data were collected by using an automatic feeder and electronic identification of individual cows from 10 July 2005 to 16 January 2006. The resulting data of the cows in primiparous and multiparous condition were categorised into groups based on the mean of their milk yield over the first 15 weeks of lactation: primiparous cows with below-average milk yield (LP) and above-average milk yield (HP) with an average of 28.44 and 34.31 kg energy-corrected milk (ECM) per day, respectively, and multiparous cows with below-average milk yield (LM) and above-average milk yield (HM) with an average of 38.70 and 44.49 kg ECM per day, respectively. The parameters of feeding behaviour were calculated based on the estimated meal criterion from pooled data. Parity, level of milk yield, and day had significant effects on some of characteristics of feeding behaviour and feed intake parameters. There was no significant difference in meal duration either between primiparous and multiparous cows or between LP and HP. However, a significant difference between LM and HM was observed. Cows in HM had shorter feeding times but a larger meal size, higher DMI, and feeding rate. Moreover, these cows displayed a stronger correlation between meal duration, daily mealtime and daily feed intake (r = 0.37 and 0.50, P < 0.001, respectively) than any other cow or group of cows of the study. Meal duration, daily mealtime, meal size and daily DMI increased on average about 32%, 20%, 35%, and 22% respectively, considering all milk yield groups from the 2nd to 15th week of lactation.     

胡萝卜对奶牛产奶量及乳成分的影响

试验通过在产奶牛日粮中添加胡萝卜,研究胡萝卜不同饲喂量对舍饲奶牛的奶产量和乳成分的影响。试验牛选用中国荷斯坦奶牛,体重500~600 kg,胎次为头胎、泌乳100 d左右的健康荷斯坦奶牛30头,采用完全随机区组设计,分为3个处理组,试验1组为对照组(基础日粮),试验2组(基础日粮+5 kg胡萝卜)、试验3组(基础日粮+7.5 kg胡萝卜)为试验组,基础日粮由全株青贮玉米、羊草和精料组成。研究结果显示,奶牛在添加胡萝卜后能够显著提高产奶量,90 d后试验2组的产奶量比对照组提高了11.94%(P<0.05),试验3组的产奶量比对照组提高了16.17%(P<0.05),牛奶的风味也得到很大的改善。     

Effects of ear corn silage supplementation on milk production and milk fatty acid profiles in grazing dairy farms

This study investigated the effects of substituting ear corn silage (ECS) for commercial formula feed on milk production and milk fatty acid profiles in grazing dairy farms during the summer season. A field survey was conducted on five grazing dairy farms in every summer month of 2017, 2018, and 2019. Three of the five farms substituted fresh ECS for the commercial formula feed at a ratio of 2:1 from July of each year (ECS farms). Other farms maintained the same feeding management as before (non‐ECS farms). An interview survey was conducted on each farm to calculate feed intake and milk yield per cow. Feed and milk samples were collected in each survey. Milk compositions and milk fatty acid profiles were determined. The substitution of ECS for the commercial formula feed did not affect milk yield or milk composition, but ECS farms maintained low levels of milk urea compared with non‐ECS farms (p < .01). The ECS substitution also influenced some of the milk fatty acid proportions; C16:0 and C16:1 increased, and trans‐11 C18:1, cis‐9,trans‐11 C18:2, and the sum of polyunsaturated fatty acids decreased, while these fatty acid proportions were maintained in non‐ECS farms throughout the summer season (p < .05).     

Nutrient sufficiency in beef cows grazing on a dwarf bamboo‐dominated forestland pasture in Japan

The nutritional status of cows grazing on a 120‐ha public alpine forestland pasture dominated by the dwarf bamboo Sasa senanensis located in central Japan was evaluated over the course of 2 years. Data were collected during grazing seasons in three periods: early (June), mid‐ (August) and late (late September–early October) periods. During these periods, the number of experimental Japanese Black cows varied between three and six. With the exception of the dry matter (DM) intake in 2005 and the crude protein (CP) digestibility in 2006, the DM and CP intake and digestibility were lower in the mid‐ and late periods than in the early period for both years (P < 0.05). Metabolizable energy intake was slightly insufficient for the requirement of the cows in the late period of 2005; in the mid‐ and late periods of 2006, the metabolizable energy intake was 0.4 to 0.5 times the requirement. These results suggest that the energy intake of cows grazing on forestland pasture dominated by S. senanensis would not satisfy their requirements starting in the mid‐period (August) grazing, even though the pasture had abundant herbage resources during these periods.     

Feed intake, lactation performance, blood metabolites and fertility in early lactation dairy cows grazing a timothy pasture

The present study was conducted to investigate feed intake, milk yield, milk composition, blood metabolites and fertility in early lactation dairy cows grazing a timothy pasture. Fourteen multiparous Holstein cows that calved between 20 May and 19 July were used over a 3‐year period. The stocking rate was 3.6–4.3 cow/ha. Concentrates were fed separately at 9.5–11.5 kg/day per cow (dry matter basis) from 1 to 13 weeks postparturition. Herbage intake was estimated using chromium oxide as an indigestible marker. The mean contents of crude protein, total digestible nutrients and neutral detergent fiber of pasture during the 3‐year study period were 22.3%, 71.8% and 51.7%, and those of total diet were 18.9%, 77.3% and 40.3%, respectively. The mean herbage dry matter intake was 13.0 kg/day from 2 to 13 weeks postparturition during the study, total dry matter intake was 23.7 kg/day, the total digestible nutrients sufficiency rate was 105%, milk yield was 39.7 kg/day, and milk fat percentage was 3.30%. The decrease in bodyweight postparturition was slight. Urea nitrogen concentrations in serum were below 18.3 mg/dL. The mean days to first estrus and days open were 36 and 104 days, respectively. These results indicate that energy deficiency, decrease in bodyweight and fertility in early lactation barely occur when high producing dairy cows are fed enough grazing grass and suitable concentrates.     

Effects of continuous low dose infusion of lipopolysaccharide on inflammatory responses,milk production and milk quality in dairy cows

The objective of this study was to evaluate the effects of continuous low dose infusion of lipopolysaccharide (LPS) on inflammatory responses and milk production and quality in lactating dairy cows. Eight Holstein cows were assigned to two treatments in a cross‐over experimental design. Cows were infused intravenously either with saline solution or with saline solution containing LPS from Escherichia coli O111:B4 at a dose of 0.01 μg LPS/kg body weight for approximately 6 hr each day during a seven‐day trial. The clinical symptoms and milk production performance were observed. Milk samples were analysed for conventional components, fatty acids and amino acids. And jugular vein and mammary vein plasma samples were analysed for concentrations of cytokines and acute phase proteins. LPS infusion decreased feed intake and milk yield. An increase in body temperature was observed after LPS infusion. LPS infusion also increased plasma concentrations of interleukin‐1β, serum amyloid A, LPS‐binding protein, C‐reactive protein and haptoglobin. LPS infusion decreased the contents of some fatty acids, such as C17:1, C18:0, C18:1n9 (trans) and C18:2n6 (trans), and most amino acids except for methionine, threonine, histidine, cysteine, tyrosine and proline in the milk. The results indicated that a continued low dose infusion of LPS can induce an inflammatory response, decrease milk production and reduce milk quality.     

复合益生菌制剂对奶牛泌乳性能及乳品质的影响

为研究复合益生菌制剂对奶牛泌乳性能及乳品质的影响,试验选取45头泌乳期相近的荷斯坦奶牛,随机分为3组,对照组、试验1组、试验2组,每组3个重复,每个重复5头。对照组饲喂基础日粮,试验1、2组分别在基础日粮中添加1%、2%的复合益生菌制剂,试验期为60d。结果表明:试验2组在第10、30、60天奶牛产奶量较对照组分别提高2.28%、0.62%、9.08%(P<0.05),试验1组在第10、60天较对照组分别提高4.6%、8.9%(P<0.05);第30天时,试验1、2组乳中总固形物含量较对照组均显著性提高(P<0.05),乳糖率、乳蛋白率、乳脂率之间差异不显著(P>0.05);第60天时,与对照组相比,试验1、2组乳中乳糖率分别提高了4.41%、7.02%(P<0.05),乳蛋白率提高了4.16%、9.97%(P<0.05),总固形物含量提高了2.44%、3.02%(P<0.05),乳脂率含量之间差异不显著(P>0.05)。综上,日粮中添加复合益生菌制剂可有效提高奶牛产奶量及乳品质,且添加2%复方益生菌制剂效果更优。     

Effect of the type of silage on milk yield,intake and rumen metabolism of dairy cows grazing swards with low herbage mass

The aim of this study was to evaluate the effect of herbage allowance (HA) and type of silage supplemented (TS) on milk yield, dry matter intake (DMI) and metabolism of dairy cows in early lactation. Thirty‐six Holstein‐Friesian dairy cows were allocated to four treatments derived from an arrangement of two HA (LHA = 17 or HHA = 25 kg of DM/cow/day) and two TS (grass (GS) or maize (MS)). Herbage allowance had no effect on DMI or milk yield. Rumen pH and NH₃‐N concentration were not affected by HA. The efficiency of microbial protein synthesis in the rumen (microbial protein (MP)) was affected by HA with 21.5 and 23.9 g microbial nitrogen per kg ruminal digestible organic matter for LHA and HHA, respectively (P < 0.05). Supplementation with MS showed higher values of milk yield by 2.4 kg/cow/day (P < 0.001), milk protein content by 0.10 % (P < 0.023) and herbage DMI by 2.2 kg/cow/day, and showed lower values for milk urea compared to GS (P < 0.001). The former results suggest that TS had a greater effect on milk yield, total feed intake and energy intake than increase in herbage allowance; however, increase in HA had greater effects on MP than TS.     

复合酶制剂对瘤胃发酵及泌乳早期奶牛生产性能的影响

本试验旨在研究添加不同水平复合酶制剂对瘤胃发酵及奶牛生产性能的影响。试验一以奶牛全混合日粮作为底物进行体外瘤胃发酵试验,分为4组,即对照组不添加酶制剂,试验1、2和3组的酶制剂添加量分别为日粮浓度的0.10%、0.15%和0.20%,每组设9个重复。每个重复准确称取0.500 g底物,在体外发酵产气自动记录装置上发酵48 h,测定其发酵参数和营养物质降解率。结果表明:复合酶制剂显著提高发酵液中总挥发性脂肪酸和乙酸浓度(P<0.05);试验组中粗蛋白(P<0.05)和中性洗涤纤维(P<0.01)降解率显著高于对照组。试验二选择体重、胎次、泌乳天数和产奶量相近的泌乳早期荷斯坦奶牛36头,采用随机区组设计分为4组,即对照组和试验1、2和3组,对照组不添加酶制剂,试验1、2和3组分别添加0.10%、0.15%和0.20%的酶制剂,每组9个重复,试验期8周,测定产奶量和乳成分含量,计算3.5%乳脂校正乳。结果表明:复合酶制剂显著提高3.5%乳脂校正乳产量(P<0.05),0.10%、0.15%和0.20%组比对照组分别提高3.88、4.27和2.26 kg·d^-1。0.15%组的乳脂率显著高于对照组(P<0.05),比对照组高12.7%。结论添加复合酶制剂有利于瘤胃发酵和提高生产性能,且添加量为0.15%时效果较好。     

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.     

植物甾醇对泌乳前期奶牛产奶量及乳成分的影响

根据年龄、胎次、泌乳时间和产奶量选择24头泌乳奶牛,随机分为对照组、试验Ⅰ组和试验Ⅱ组。对照组饲喂奶牛场配制的全混合饲料,试验Ⅰ和Ⅱ组每头奶牛日粮中分别添加40 g/d和80 g/d植物甾醇,研究植物甾醇对奶牛生产性能的影响。结果表明,与对照组相比,试验Ⅰ和Ⅱ组奶牛的产奶量分别提高了2.07 kg/d(5.64%,P0.05)和1.74 kg/d(4.75%,P0.05);试验Ⅰ和Ⅱ组奶牛乳脂率分别提高了8.22%(P0.01)和2.97%(P0.05);乳蛋白率分别提高了2.45%(P0.05)和1.05%(P0.05);非脂固形物分别提高了1.29%(P0.05)和0.23%(P0.05),体细胞数分别下降了37.31%和19.34%,但差异均不显著(P0.05);牛奶中乳尿素氮含量分别降低了5.29%(P0.05)和7.58%(P0.01)。结果表明泌乳前期奶牛补饲一定量的植物甾醇能够提高产奶量和改善乳成分。