驴初乳理化性质和主要成份的动态变化

对驴初乳物理性质和化学组成研究。结果表明,驴初乳的相对密度、折光度、电导率、酸度均高于常乳,而pH 值低于常乳;驴初乳中蛋白质、灰分、脂肪含量均随泌乳期延长呈下降趋势;分娩后第一次(6h)所挤初乳中乳糖含量最低,之后随泌乳期延长乳糖含量呈上升趋势;随泌乳期的延长,初乳中各项指标逐渐接近常乳。应用亲和色谱法测定驴初乳免疫球蛋白含量,结果表明,随泌乳期的延长驴初乳中IgG 含量呈下降趋势。     

水牛初乳中免疫因子和生长因子质量浓度的研究

研究水牛初乳中免疫球蛋白IgG,IgA和类胰岛素样生长因子(IGF-I)质量浓度的变化特点。用ELISA方法检测水牛分娩后7d内初乳样品的IgG,IgA和IGF-I质量浓度,同时检测3种成分在水牛常乳中的质量浓度。结果表明:分娩后3h的水牛初乳IgG,IgA和IGF-I质量浓度最高,分别为78.22g/L,8.83g/L和1099.78μg/L,常乳中的质量浓度分别为1.87g/L,0.71g/L和358.30μg/L。IgG在泌乳的第1天内下降91.18%,IGF-I下降57.02%,IgA在头2d内下降85.84%,之后缓慢下降接近常乳。因此,水牛泌乳最初的1~2d内初乳含有丰富的IgG,IgA和IGF-I,具有很高的开发利用价值。     

摩拉×西林水牛乳化学组成变化的研究

本实验采用7头1胎的摩拉×西林水牛，分别在产犊后2h、12h、24h、36h、48h、3d、4d、5d、6d、7d、15d、30d、60d、90d、120d、150d、180d、210d采集乳样，称量产乳量，测定乳的物理性质和化学组成。结果表明：摩拉×本地水牛的泌乳高峰出现在产后第三个月（126．56kg），210d总产量805．47kg，平均日产量3．84kg：水牛产犊后2h乳的pH为6．23，乳糖2．33％，之后逐渐上升，15d之后分别在pH6．51～6．55，乳糖4．42％-4．79％之间变化；2h时乳的酸度为36．73。T，之后逐渐下降，15d之后在19．43-23．15。T之间变化；2h时乳密度、蛋白质、固形物分别为1．057、18．23％、31．460％，3d内迅速下降，然后分别在1．028～1．031、4．83％~6．02％、19．12％~20．59％之间变化：脂肪含量在2h为9．73％，之后逐步上升，36h时达到最高值11．57％，之后呈缓慢下降趋势，4d时为9．76％，之后在8．26％～9．06％之间变化：酪蛋白在粗蛋白中的比例逐步上升，2h时为40．15％，5d时达到79．13％，之后在81．07％～83．23％变化。     

四川部分山羊品种(系)产奶量及乳营养分析

母羊泌乳量高低及乳的营养是影响羔羊成活及生长速度的两个重要因素。本实验对四川4个山羊品种(系)的产奶量及乳的常规营养成分进行研究。结果表明:4个山羊品种(系)产奶量高低顺序为天府肉羊>简阳大耳羊>乐至黑山羊>营山黑山羊,依次为(84.28±5.11)、(81.90±3.27)、(80.63±4.48)、(65.08±2.43)kg。产后48h内初乳中的干物质和蛋白质含量均迅速下降;脂肪含量先上升后下降,然后再上升;乳糖含量差异不大,相对稳定于4～5g/100mL之间。产后2h时蛋白水平高低为营山黑山羊>天府肉羊>乐至黑山羊>简阳大耳羊;乳中干物质含量为天府肉羊>营山黑山羊>乐至黑山羊>简阳大耳羊;脂肪含量为乐至黑山羊>简阳大耳羊>天府肉羊>营山黑山羊;乳糖含量为简阳大耳羊>乐至黑山羊>天府肉羊>营山黑山羊。2月龄所测定的常乳中,蛋白质与干物质含量最高的为天府肉羊,脂肪含量最高的为营山黑山羊,乳糖含量最高的为简阳大耳羊。     

HPLC法检测牛初乳中lgG含量

建立了牛初乳中IgG的高效液相色谱检测法,并测定了 初乳中IgG的经时变化过程。结果显示,IgG浓度在0.2～ 15mg/mL的范围内峰面积与浓度呈现良好的线性关系, 回收率实验平均大于98.5％。采用本法测定了六头幽门螺 杆菌免疫牛初乳中IgG及两头正常牛初乳中IgG的经时 变化过程。母牛分娩后24h内,初乳中免疫球蛋白IgG平 均含量在40～70mg/mL之间;3d后,初乳中免疫球蛋白 总量下降较快;至第7d,初乳中免疫球蛋白含量平均在 1～5mg/mL之间。     

HPLC法检测牛初乳中IgG含量

建立了牛初乳中IgG的高效液相色谱检测法,并测定了初乳中IgG的经时变化过程.结果显示,IgG浓度在0.2～15mg/mL的范围内峰面积与浓度呈现良好的线性关系,回收率实验平均大于98.5%.采用本法测定了六头幽门螺杆菌免疫牛初乳中IgG及两头正常牛初乳中IgG的经时变化过程.母牛分娩后24h内,初乳中免疫球蛋白IgG平均含量在40～70mg/mL之间;3d后,初乳中免疫球蛋白总量下降较快;至第7d,初乳中免疫球蛋白含量平均在1～5mg/mL之间.     

含24种乳抗体免疫乳的制备

以24株人肠道病原菌（包括病原性大肠杆菌12株、沙门氏菌8株、志贺氏菌3株、小肠结肠炎耶尔森氏菌1株）作为抗原，对乳牛进行系统免疫，免疫乳与非免疫乳乳中IgG含量无显著差异。系统免疫并不增加乳中IgG的含量，但IgG的抗体特异性大大增强，所得的免疫初乳中乳抗体对24种不同病原菌的凝集价为2^8-2^12，为普通初乳中乳抗体凝集价的32－256倍；免疫常乳中乳抗体对24种不同病原菌的凝集价为2^5-2^8，为普通乳中乳抗体凝集价的8－128倍。     

不同泌乳时间内内蒙古阿拉善双峰驼驼乳化学组成变化分析

本研究对10匹内蒙古阿拉善双峰驼驼乳的化学组成进行了分析。结果表明，第1次所挤初乳中总干物质为20．16％，在2-30d内变化范围为17．42％18．22％，到90d下降为14．31％。第1次所挤初乳中蛋白质为14．23％，12h后下降到9．63％，之后进一步下降，在7、15、30及90d分别为7．40％、5．32％、4．87％和3．55％。乳糖含量在1～90d泌乳期内变化较小，为4．24％-4．44％。第1次所挤初乳脂肪含量为0．27％，到24h增加到4．18％，30d时为6．91％，90d又下降到5．65％。第1次所挤初乳中灰分含量为1．22％，到12h下降到0．99％，在90d泌乳期内稳定在0．82％～0．98％范围内。第1次所挤的初乳中，WPN占总氮58．74％，CN占总氮38．57％，NPN仅占总氮的2．69％；24h，WPN、CN及NPN分别占总氮的32．54％、65．08％及2．38％。随泌乳进行，驼乳氮分布中CN逐渐升高，WPN逐渐降低，2-90d NPN占总氮变化较小，为5．26％～7．89％。驼乳中C12：0～C18：0偶数长链饱和脂肪酸占总脂肪酸的57．54％，其中C16：0、C18：0及C12：0分别占总脂肪酸的30．12％、15．15％和11．49％，C18：1～C18：3长链多不饱和脂肪酸占总脂肪酸组成的30．25％，其中以C18：1脂肪酸为主，为26．05％。第1次所挤的初乳中钙、磷含量最高，分别为222．58mg／100g和153．74mg／100g；钙、磷、钠、钾及氯在3～90d变化范围分别在154．57～186．87、116．82～141．67、59．5～79．5、150．0～191．0和80．9～152．0mg／100g。初乳中VA、VC含量低于霄乳，VE、VB1高于常乳，VD、VB2及VB6与常乳相近。90d驼乳中VA、VE、VB1、VB2、VB6、VC和VD分别为0．97mg／L和1．45、0．124、1．24、0．54和29．60mg／L和692IU／L。     

免疫初乳中乳抗体对大肠杆菌和沙门氏菌所致小鼠腹泻的被动免疫保护

以24株人肠道病原菌(包括病原性大肠杆菌12株、沙门氏菌8株、志贺氏菌3株、小肠结肠炎耶尔森氏菌1株)作为抗原，对乳牛进行系统免疫，免疫乳与非免疫乳乳中IgG含量无显著差异。系统免疫并不增加乳中IgG的含量，但IgG的抗体特异性大大增强，所得的免疫初乳中乳抗体对24种不同病原菌的凝集价为2^8-2^12，为普通初乳中乳抗体凝集价的32—256倍。采用硫酸胺盐析从免疫初乳中分离乳抗体，免疫初乳中的特异性IgG乳抗体较普通初乳中的IgG可显著抑制大肠杆菌和沙门氏菌的生长。动物试验表明，免疫乳中特异性的IgG对大肠杆菌和沙门氏菌所致小鼠腹泻具有很好的保护作用，而普通乳中非特异性的IgG则无此作用，这是由于IgG的特异性所决定。     

中国荷斯坦牛泌乳早期乳常规成分及乳蛋白组分变化规律的研究

对扬州大学实验农牧场7头中国荷斯坦牛泌乳早期乳常规营养成分、酸度及乳蛋白组分的相对含量进行研究。结果表明，产犊后1h的乳脂率、乳蛋白含量、总固形物含量、滴定酸度、密度最高，而pH值最低，随后乳脂率、乳蛋白率、总固形物含量、滴定酸度密度急剧下降，到60h时接近常乳水平，而pH值逐渐上升，到第7d时接近常乳水平。产犊后1h初乳中免疫球蛋白的相对含量最高，为20．6％，到第5d时接近常乳水平。研究表明，产犊后3d内所产的乳最具有开发价值。     

The carbohydrate composition of human milk

The carbohydrate content of breast milk was investigated by capillary gas liquid chromatography. The milk samples obtained from 16 normal lactating mothers contained glucose, galactose, lactose, and 3-fucosidolactose. The content of monosaccharides in breast milk was 2-12 times higher than that in cow's milk. The lactose content amounted to 84-95%, whereas the ratio of alpha- tox beta-froms was within 0.92-0.95%. Breast milk was found to contain alpha- and beta-forms of 2- and 3-fucosidolactose which do not occur in cow's milk. The content of these forms accounted for 3%. The biological role of breast milk carbohydrates is discussed.     

Prepartum level of dietary cation-anion difference fed to nulliparous cows: Lactation and reproductive responses

Objectives were to determine the effects of 3 levels of dietary cation-anion difference (DCAD) fed prepartum to nulliparous cows on productive and reproductive performance. We enrolled 132 pregnant nulliparous Holstein cows at 250 (248–253) d of gestation in a randomized block design. Cows were blocked by genomic merit of energy-corrected milk yield and assigned randomly to diets varying in DCAD, +200 (P200; n = 43), −50 (N50; n = 45), or −150 (N150; n = 44) mEq/kg of dry matter (DM). Dietary treatments were fed during the last 22 d of gestation and, after calving, postpartum cows received the same lactation diet. Productive performance was evaluated for the first 14 wk of lactation, and reproduction was assessed until 305 d postpartum. Intake of DM prepartum decreased linearly (results presented in sequence as least squares means ± standard error of the mean, P200 vs. N50 vs. N150) with a reduction in DCAD (9.0 vs. 8.9 vs. 8.4 ± 0.1 kg/d), which resulted in linear decreases in net energy balance (0.34 vs. 0.20 vs. −0.36 ± 0.20 Mcal/d), body weight change (1.1 vs. 0.8 vs. 0.3 ± 0.1 kg/d), and mean body weight (652 vs. 649 vs. 643 ± 2 kg) prepartum. Treatment did not affect yield of colostrum (6.3 vs. 5.8 vs. 5.1 ± 0.6 kg) or the contents or yields of fat, protein, lactose, IgG, Ca, or Mg in colostrum. Intake of DM (19.4 vs. 19.2 vs. 19.0 ± 0.2 kg/d), yields of milk (36.6 vs. 36.7 vs. 35.8 ± 0.6 kg/d) or energy-corrected milk (36.7 vs. 36.3 vs. 35.9 ± 0.5 kg/d), feed efficiency (1.93 vs. 1.92 vs. 1.93 ± 0.03 kg of energy-corrected milk per kilogram of DM intake), and content and yield of milk components did not differ among treatments during the first 14 wk of lactation. Prepartum DCAD did not affect the cumulative milk yield by 305 d of lactation (9,653 vs. 10,005 vs. 9,918 ± 196 kg). Of the 132 cows, 40 P200, 45 N50, and 43 N150 received at least 1 artificial insemination (AI), and treatment did not affect pregnancy per AI at first (32.5 vs. 35.6 vs. 37.2%) or all AI (30.6 vs. 33.9 vs. 40.2%), although reducing the DCAD increased the proportion of cows pregnant by 305 d postpartum (76.7 vs. 88.9 vs. 93.2%) without altering the rate of pregnancy. Collectively, manipulating the DCAD of prepartum diets, from +200 to −150 mEq/kg of DM, fed to late gestation nulliparous cows did not affect subsequent lactation productive performance, but may have provided some benefit to reproduction, which warrants further confirmation.     

Associations of elevated nonesterified fatty acids and β-hydroxybutyrate concentrations with early lactation reproductive performance and milk production in transition dairy cattle in the northeastern United States

The objectives were to evaluate the effects of elevated pre- and postpartum nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA) concentrations during the transition period on reproductive performance and milk production in dairy cattle. In a prospective cohort study of 91 freestall, total mixed ration-fed herds in the northeastern United States, blood samples were collected from approximately 15 prepartum and 15 different postpartum transition animals in each herd. All samples were stratified based on pre- or postpartum status at the time of sample collection, and 2,259 and 2,290 animals were used to evaluate reproductive and milk production performance, respectively. Reproductive performance was assessed by time to conception within 70 d post-voluntary waiting period (VWP) and milk production was assessed using mature-equivalent 305-d (ME305) milk yield estimated at 120 d in milk. While controlling for body condition score (BCS), calving season, median ME305 milk production, and parity, NEFA and BHBA concentrations were evaluated with time to event analysis to investigate reproductive performance. These same predictor variables were used to determine the effects of elevated NEFA and BHBA concentrations on ME305 milk yield with herd as a random effect. Heifers and cows were grouped in the final analyses if the results between groups were similar. In all animals sampled prepartum, the risk of pregnancy within 70 d post-VWP was reduced by 19% when NEFA concentrations were ≥0.27 mEq/L. In all animals sampled postpartum, those with NEFA concentrations ≥0.72 mEq/L had a 16% decrease in risk of pregnancy and those with BHBA concentrations ≥10 mg/dL had a 13% decrease in risk. In cows and heifers, ME305 milk yield was decreased by 683 kg when prepartum NEFA concentrations were ≥0.33 mEq/L. In heifers sampled postpartum, ME305 milk yield was increased by 488 kg when NEFA concentrations were ≥0.57 mEq/L and increased by 403 kg when BHBA concentrations were ≥9 mg/dL. In cows sampled postpartum, ME305 milk yield was decreased by 647 kg when NEFA concentrations were ≥0.72 mEq/L and decreased by 393 kg when BHBA concentrations were ≥10 mg/dL. With the exception of milk production in heifers, this study indicates that increased concentrations of serum NEFA and BHBA had a detrimental effect on reproductive performance and milk production.     

Agreement of predicted 305-day milk yields relative to actual 305-day milk weight yields

The objectives of this study were to compare the multiple trait prediction (MTP) model estimate of 305-d lactation yield with the 305-d daily milk yield data from on-farm automated meters and software and to examine the accuracy of electronic identification (ID). Twenty-four-hour milk and component yields are calculated by using milk weights and samples collected 8 to 10 times/yr by Dairy Herd Improvement (DHI) organizations. Daily milk weights were collected from cows on 20 Canadian farms that used parlor milking systems with electronic ID and that were enrolled in a regular DHI program. A total of 10,175 DHI test days from 1,103 cows with complete 305-d lactation yields were entered into the MTP model, and lactation yields were predicted. Test days were grouped into first, second, and third and greater lactations and within each lactation group, days in milk were categorized in 3 stages (5 to 60, 61 to 120, and 120 to 305 d in milk) for a total of 9 classes. Agreement analysis was used to compare the 305-d sum of daily milk to the MTP 305-d lactation yield predictions by using inputs from test days throughout the lactations. Results indicated that the MTP model overestimated lactation yields across all parity groups, ranging from 310 to 1,552 kg in parity 1, 640 to 2,000 kg in parity 2, and 567 to 1,476 kg in parity 3 and greater. A preliminary examination of electronic ID accuracy was conducted on 4 farms. Two electronic ID systems were examined for cow ID accuracy by verifying the ID number appearing in the parlor with the corresponding ear tag number. There were no ID errors on 3 of 4 farms tested and only a very small number of errors (3/80) on the fourth farm, indicating that the electronic ID systems used in milking parlors identify cows accurately.     

Differences in body temperature regulation during heat stress and seasonal depression in milk yield between Holstein,Brown Swiss,and crossbred cows

It is not clear whether cattle that are genetically superior in regulation of body temperature during heat stress are also better able to sustain milk production during hot conditions. Objectives were to evaluate differences in body temperature regulation during heat stress between Holstein, Brown Swiss, and crossbred cows under semi-tropical conditions and test whether the seasonal depression in milk yield was greater for genetic groups less able to regulate body temperature. For the first objective, conducted during heat stress, vaginal temperature was measured at 15-min intervals for 5 d in 133 pregnant lactating cows. Vaginal temperatures were affected by time and interaction between genetic group and time. Vaginal temperatures were higher for Holsteins for most times of the day. Moreover, the maximum daily vaginal temperature was higher for Holstein (39.8 ± 0.1°C) than for Brown Swiss (39.3 ± 0.2°C) or crossbreds (39.2 ± 0.1°C). For the second objective, 6,179 lactation records from 2,976 cows were analyzed to determine effects of genetic group and season of calving (cool season = Oct to March; warm season = April to Sept) on 305-d milk yield. Milk yield was affected by genetic group and season but not by the interaction of genetic group and season. The difference in average 305-d milk yield between cows calving in cool versus hot weather was 310 kg (4% decrease) for Holstein, 480 kg (7% decrease) for Brown Swiss, and 420 kg (6% decrease) for crossbreds. In conclusion, Brown Swiss and crossbreds regulated body temperature during heat stress better than Holsteins but these breeds were not more resistant to heat stress with respect to milk yield. Thus, genetic differences in thermotolerance are likely to exist that are independent of regulation of body temperature.     

Growth and reproduction characteristics of purebred and crossbred dairy cattle in first lactation

Breed additive, maternal, and heterozygotic effects on 11 monthly postpartum body weights, average size, weight gain, age at first calving, and days open were estimated by linear regression analyses from records of 680 purebred and crossbred animals. Calving year, age, and milk yield were significant environmental effects. Positive regressions of age on body weights indicated late calving cows were heaviest postpartum and had most days open. Negative regressions of milk yield on weight gain and postpartum weight showed greatest losses of weight associated with highest yields. There were breed differences in growth; purebreds highest to lowest were Brown Swiss, Holstein, Red Dane, Jersey, and Ayrshire and for weight gain, Brown Swiss, Ayrshire, and for weight gain, Brown Swiss, Ayrshire, Jersey, Holsteins, and Red Dane. Crosses were superior to purebreds in these traits. Additive effects of Holstein were greater than Ayrshire, Jersey, and Red Dane for postpartum body weights and average size. All constants for heterozygotic effect combinations were significant for postpartum weights and average size. Heterozygosity effects increased in magnitude with advancing lactation. Generally, age at first calving and postpartum interval to conception reflected little heterozygotic or maternal effects. There was some indication of breed differences in mean and additive effects for age at first calving.     

Induced lactation in heifers: Effects of dexamethasone and age at induction on milk yield and composition

Milk production in heifers induced into lactation is lower than that of postpartum primiparous cows. A method to improve milk production in induced lactations may provide opportunities for increased profitability as well as increase our understanding of the mechanisms that regulate mammary gland development and colostrum composition. The present study was conducted to determine if dexamethasone administration at the onset of milking or age at lactation induction would affect milk production in heifers induced into lactation. Holstein heifers at 14 [n = 20; 354 ± 38 kg of body weight (BW)] and 18 mo of age (n = 20; 456 ± 30 kg of BW) were assigned randomly to dexamethasone (DEX) or control (CON) treatment groups in a 2× 2 factorial arrangement with age and dexamethasone treatment as the 2 factors. Heifers were induced into lactation with daily subcutaneous injections of estradiol-17β and progesterone (0.075 and 0.25 mg/kg of BW per d, respectively) on experimental d 1 to 7. They also received bovine somatotropin (bST) every 14 d beginning on experimental d 1. Milking began on experiment d 18 (lactation d 1). Dexamethasone (10 mg) was administered on lactation d 1 and 2 following the morning milking; CON heifers did not receive dexamethasone. Milk yield from d2 to 15 of lactation of heifers receiving DEX (7.8 kg/d) was greater than that of CON heifers (6.0 kg/d) but was similar thereafter through 305 d of lactation (18.2 kg/d). Milk production to d 11 was similar for 14- and 18-mo-old heifers but was greater for 18- (18.9 kg/d) than for 14-mo-old animals (17.4 kg/d) through 305 d in milk. Milk fat percentage increased initially and was greater in DEX (4.51%) compared with CON (3.53%) heifers until 21 d in milk. Milk protein and lactose concentrations were not affected by DEX treatment. Age at induction did not affect milk fat, protein, or lactose percentages. Mean milk IgG concentration declined from 107.4 mg/mL on d 1 to 5.0 mg/mL on d 7 of lactation, tended to be greater for 18- compared with 14-mo-old heifers, and was not different due to DEX treatment. Administration of DEX to heifers induced into lactation increased initial milk production during the first 2 wk of lactation but this effect did not persist through 305 DIM. Treatment with DEX appeared to stimulate mammary cell differentiation but did not change the rate of decline of milk IgG concentrations. Higher milk yield in 18-mo-old heifers may be due to greater mammary epithelium, higher body mass, or both.     

Effects of week of lactation and genetic selection for milk yield on milk fatty acid composition in Holstein cows

Control (CL) and select line (SL) dairy cows (n = 22) managed identically but differing in milk yield (>4100 kg/305 d) were used to determine differences in milk fatty acid profile as lactation progressed. Milk yield was recorded daily and milk samples were collected during wk 1, 4, 8, 12, and 16 postpartum for milk composition analysis. Milk samples from wk 1, 8, and 16 were also analyzed for fatty acid composition. Select-line cows produced more milk (44.4 vs. 31.2 kg/d) and milk components than CL cows during the 16-wk period. There was no difference in rate of milk yield increase, but peak milk yield for SL cows was greater and occurred later in lactation. There were no differences in milk SCC or milk fat, protein, or lactose content. Selection for milk yield did not affect the content of most individual milk fatty acids; however, compared with CL, SL cows had a reduced Delta(9)-desaturase system and tended to produce milk with lower monounsaturated fatty acid content. Selection for milk yield did not affect milk fatty acid origin but the percentage of de novo fatty acids increased and preformed fatty acids decreased as lactation progressed. Milk fat trans-11 18:1 and cis-9,trans-11 conjugated linoleic acid increased with progressing lactation (10.7 vs. 14.1 and 3.1 vs. 5.4 mg/g, or 31 and 76%, respectively) and were correlated strongly among wk 1, 8, and 16 of lactation. Temporal changes in the Delta(9)-desaturase system occurred during lactation but these changes were not correlated with milk fat cis-9,trans-11 conjugated linoleic acid content. Results indicate prolonged genetic selection for milk yield had little effect on milk fatty acid composition, but milk fatty acid profiles varied markedly by week of lactation.     

Effects of recombinant methionyl bovine somatotropin (sometribove) in high producing cows milked three times daily

Effects of daily sometribove administration on milk yield and composition, body condition score, BW, and SCC were evaluated in Holstein cows milked three times daily. Lactating cows (n =104) were assigned randomly to control or sometribove-treated (25 mg/d) groups. The experimental period was 16 wk, consisting of 2-wk pretreatment, 12-wk treatment, and 2-wk posttreatment periods. All cows were injected once daily starting at 53 to 180 d postpartum, housed in free stalls, and fed one of five total mixed rations according to milk production. Body weights were measured weekly, and body condition was scored biweekly. Milk yield was recorded daily, and weekly milk samples were analyzed for fat, protein, lactose, total solids, and SCC. Milk yield and milk protein were increased 18.8% (38.6 vs. 32.5 kg/d) and 3.3% (3.1 vs. 3.0%), respectively, whereas percentage of milk fat, lactose, SNF, SCC, and BW were unaffected by treatment. Overall average body condition scores were lower for the sometribove-treated group versus control (2.2 vs. 2.4). No apparent differences in the number of cows treated for mastitis, foot rot, displaced abomasum, or lameness were observed between treatment groups. Sometribove treatment significantly enhanced milk yield (6.1 kg/d) with no apparent negative effects on health in high producing cows milked three times per day.