Prevalence and severity of foot lesions in Danish Holstein heifers through first lactation

Several studies have shown that foot lesions and clinical lameness occur before first calving and develop further during the lactation period. Lameness may cause production losses, but the relationship between foot lesions, particularly in the claw horn, and lameness in heifers is unclear. The objectives of this study were to describe the development of and evaluate the relationship between lameness and foot lesions in Danish Holsteins before and after first calving. In a longitudinal study, 147 heifers were examined for lameness and foot lesions 2–5 times over an 18-month period. Lameness was assessed by means of a visual locomotion score and foot lesion severity was recorded.The prevalence of a locomotion score 3 was 25% before calving, and 90% at approximately 250 days in milk (DIM). Prevalence of moderate to severe sole haemorrhage (SH) was 27% before calving and 56% at 250 DIM, and that of moderate to severe white line lesion (WLL) 44% before calving with a peak of 70% at 200 DIM. There was one case of white line abscess but SH was seen throughout the entire study period. Digital dermatitis (DD) was prevalent prior to first calving (15%) and peaked at 39% at 0–100 DIM. Heel horn erosion (HHE) occurred in almost all cows (93–100%) and was strongly correlated with DD (r = 0.51). The correlation coefficient between SH and WLL was also high (0.42). The relatively high correlations between WLL and both DD and HHE were more surprising (0.38 and 0.35, respectively), those between SH and both DD and HHE were moderate (around 0.18). Interdigital dermatitis was significantly correlated with both HHE and DD, but completely unrelated to SH and WLL.The overall average locomotion score increased by about one-half of a score unit from 1 month prior to calving until 250 DIM, with a large difference between herds, although this was unsurprising as cows may alter their locomotion pattern with management factors (e.g. floor properties). DD and WLL were both associated with a locomotion score 3 but of the cows with severe WLL there was no clear association between a locomotion score 3 and DD. The highest locomotion scores occurred among cows with DD but without WLL.     

Indicators of induced subacute ruminal acidosis (SARA) in Danish Holstein cows

Background

The prevalence of subacute ruminal acidosis (SARA) in dairy cows is high with large impact on economy and welfare. Its current field diagnosis is based on point ruminal pH measurements by oral probe or rumenocentesis. These techniques are invasive and inaccurate, and better markers for the diagnosis of SARA are needed. The goal of this study was to evaluate clinical signs of SARA and to investigate the use of blood, faecal and urinary parameters as indicators of SARA. Six lactating, rumen cannulated, Danish Holstein cows were used in a cross-over study with three periods. The first and second periods included two cows on control diet and two cows on nutritional SARA challenge. The third period only included two cows on SARA challenge. Control diet was a conventional total mixed ration [45.5% dry matter (DM), 17.8% crude protein, 43.8% neutral detergent fibre, and 22.5% acid detergent fibre (DM basis)]. SARA challenge was conducted by substituting control diet with grain pellets (50% wheat/barley) over 3 days to reach 40% grain in the diet. Ruminal pH was measured continuously. Blood samples were collected once daily at 7 h after feeding. Samples of faeces and urine were collected at feeding, and at 7 and 12 h after feeding. Blood samples were analysed for pCO2, pO2, pH, electrolytes, lactate, glucose, packed cell volume (PCV), and total plasma protein concentration. Milk composition, ruminal VFA, and pH of faeces and urine were measured.

Results

SARA was associated with decreased (P < 0.05) minimum ruminal, faecal and urinary pH. Daily times and areas of ruminal pH below 5.8, and 5.6 were increased to levels representative for SARA. Significant differences were detected in milk composition and ruminal VFAs. Blood calcium concentration was decreased (P < 0.05), and pCO₂ tended to be increased (P = 0.10). Significant differences were not detected in other parameters.

Conclusions

SARA challenge was associated with changes in faecal and urinary pH, blood calcium concentration and pCO₂. These may be helpful as indicators of SARA. However changes were small, and diurnal variations were present. None of these parameters are able to stand alone as indicators of SARA.     

Milk production and composition in Danish Holstein,Danish Red,and Danish Jersey cows supplemented with saturated or unsaturated fat

The aim of the experiment was to study the response in milk production and composition of substituting barley with either saturated or unsaturated fat in mixed rations (MR) for dairy cows. The experiment included 35 Danish Holstein (DH), 39 Danish Red (DR), and 31 Danish Jersey (DJ) cows from parturition until week 30 of lactation. Cows were ad libitum fed one of the three MR based on maize and grass/clover silage, barley, soybean meal, and dried sugar beet pulp. In the saturated ration (SFA), C16 rich fat substituted barley on dry matter (DM) basis; in the unsaturated ration (UFA), ground rape and linseed (0.74:0.26 ratio) substituted barley on DM basis; and in the control ration (CO), no barley was substituted. Concentrations of crude fat (CF) of total ration DM was 3.03% in CO, and in diets supplemented to intended similar fat levels 5.65% (SFA) and 5.81% (UFA), respectively. Statistical analyses were performed within breed and random regression was used to test for differences between treatment responses throughout lactations.     

Comparison of models for genetic evaluation of number of inseminations to conception in Danish Holstein cows

Number of inseminations to conception (NINS), an important fertility trait, requires appropriate approaches for genetic evaluation due to its non‐normal distribution and censoring records. In this study, we analyzed NINS in 474 837 Danish Holstein cows at their first lactation by using seven models which deal with the categorical phenotypes and censored records in different manners, further assessed these models with regard to stability, lack of bias and accuracy of prediction. The estimated heritability from four models based on original NINS specified as a linear Gaussian model, categorical threshold model, threshold linear model and survival model were similar (0.031‐0.037). While for the other three models based on the binary response derived from NINS, referred as threshold model (TM), logistic and probit models (LOGM and PROM), the heritability were estimated as 0.027, 0.063 and 0.027, respectively. The model comparison concluded that different models could lead to slightly different sire rankings in terms of breeding values; a more complicated model led to less stability of prediction; the models based on the binary response derived from NINS (TM, LOGM and PROM) had slightly better performances in terms of unbiased and accurate prediction of breeding values.     

Genetic analysis of protein yield,udder health,and female fertility in first-parity Danish Holstein cows

Abstract

Genetic parameters for protein yield, clinical mastitis, SCS, number of inseminations (NI), and days from first to last insemination (FLI) were estimated for first-parity Danish Holstein cows. The objective was to estimate genetic correlations between the five traits mentioned above and to study whether NI and FLI are measures of the same trait. Records containing information on approximately 200 000 cows were analysed using tri-variate animal models. The genetic correlations between the udder health traits and the fertility traits were favourable and in the range from 0.17 to 0.42, whereas the genetic correlations between protein yield and the fertility traits were unfavourable and ranged from 0.43 to 0.52. These results highlight the importance of continuing to emphasize functional traits in future breeding programmes. The genetic correlation between the fertility traits was 0.82. Based on this result, it cannot be concluded that NI and FLI are measures of the same trait.     

Prevalence and interrelationships of hoof lesions and lameness in Swedish dairy cows

The prevalence of hoof lesions and lameness in 4899 heifers and cows was determined at claw trimming one time in a cross-sectional study on 101 Swedish dairy farms, 1996-1998. The percentage of affected animals was 41% for heel-horn erosion, 30% for sole haemorrhages, 27% for erosive dermatitis, 21% for abnormal claw shape, 14% for white-line haemorrhages, 8.8% for white-line fissures, 8.6% for sole ulcers, 3.3% for double soles, 2.3% for verrucose dermatitis, and 1.8% for interdigital hyperplasia (IH). Seventy-two percent of all animals had at least one hoof lesion. The prevalence of lameness was 5.1%; most hoof lesions did not cause lameness. Differences between herds were substantial; the herd-specific, animal-level prevalence of lesions ranged from 25 to 98% and of lameness from 0 to 33%. Sole haemorrhages were found in all herds. The proportion of variance at the between-herd level was particularly high for heel-horn erosion (62%) and abnormal claw shape (54%). Strong correlations between lesions were found within hooves (and animals), e.g. for heel-horn erosion and dermatitis (Spearman's rank correlation, r(s)=0.36 and 0.37, respectively) and for sole and white-line haemorrhages (r(s)=0.25 and 0.28). Most hoof lesions affected hind and front hooves bilaterally, whereas the correlation between hind and front hooves generally was lower. Herds that ranked high for prevalence of sole ulcer also ranked high for sole haemorrhages and for abnormal claw shape and herds that ranked high for dermatitis also ranked high for heel-horn erosion, verrucose dermatitis and IH. Abnormal claw shape was strongly associated with sole ulcer (r(s)=0.41 at cow level)-suggesting the importance of maintaining a correct claw shape for the prevention of hoof-horn lesions.     

Gene expression profiling of peripheral mononuclear cells in lame dairy cows with foot lesions

Lameness is a major health issue and likely the single most common cause of pain and discomfort in dairy cattle. Appropriate treatment is delayed or neglected due, in part, to lack of reliable detection. Assessment of cows with lameness is currently limited to subjective visual scoring systems based on locomotion and posture abnormalities. These systems are unreliable to detect lameness, and therefore, a large number of cows remain undiagnosed. The objective of this research was to search for potential biomarkers for lameness-associated painful inflammatory foot lesions in dairy cattle using microarray-based gene expression profiling of peripheral blood mononuclear cells (PBMC). BOTL5 microarrays spotted in duplicate with cDNA representing bovine immune response genes were interrogated with cDNA samples in an eight-array, balanced complete block design with dye swap. Samples from eight lame cows with inflammatory foot lesions and from eight sound cows were pair-matched by age, weight, days in lactation, and pregnancy status at time of PBMC collection and directly compared with each other on individual arrays. Statistical analysis of resulting fluorescence intensity data revealed 31 genes that were putatively differentially expressed in lame versus sound cows (P < 0.05). Of these, BLASTn analysis and gene ontology information showed that 28 genes had high similarity or homology to known human and/or rodent genes. Validation of 15 of these genes known to be important in inflammation and pain was carried out using relative quantitative real-time RT-PCR, which confirmed the up-regulation of interleukin (IL)-2 (12.68 ± 1.47-fold increase) and IL-10 (2.39 ± 0.55-fold increase), matrix metalloproteinase-13 (MMP-13) (10.44 ± 1.14-fold increase), and chemokine C–C motif receptor-5 (CCR5) (5.26 ± 1.05-fold increase), in lame relative to sound cows (P ≤ 0.05). Similarly, granulocyte-macrophage colony-stimulating factor receptor alpha chain precursor (GM-CSF-R-alpha) (2.30 ± 0.63-fold increase) and IL-4 (2.06 ± 0.59-fold increase) showed a tendency (P = 0.10) for up-regulation in lame compared to sound cows. PBMC co-expression of IL-2, MMP-13, CCR5 and IL-10, and potentially IL-4 and GM-CSF-R-alpha appears to be a promising, objective sign of lameness-related inflammatory foot lesions in dairy cattle. In conclusion, this study revealed potential biomarkers of the presence of foot lesions that could boost diagnostic accuracy of lameness and, ultimately, help identify animals in need of pain relief.     

Chronic copper poisoning in two Holstein cows

Chronic copper poisoning with an acute hemolytic crisis is described in 2 mature Holstein dairy cows from separate herds. Toxic concentrations of copper were present in the serum and in liver and kidney tissues of each cow. There was no history of environmental or dietary exposure to excessive quantities of copper. No further clinical cases of chronic copper toxicosis were observed in the herds. As well as massive hemolysis, in both cows there was involvement of other organ systems including the liver and kidneys which contributed to the clinical course of the disease.     

Reasons for culling in French Holstein cows

The study describes the profiles of culled cows in order to assess the possible contribution to economic losses due to health disorders. Data regarding dates of birth, final calving and culling, parity at culling, milk yield at the two first test-days of the final lactation and reason(s) for culling were collected in a 5-year survey, carried out from 1989 to 1994 in 84 commercial Holstein farms in western France. Polytomous logistic regression was used to assess the relationship between parity, calving-to-culling interval, milk yield and eight groups of primary culling reasons (i.e. udder disorders; infertility or reproductive disorders; lameness or foot/leg defects; emergency culling reasons; other health disorders; low milk yield; sales for dairy purpose; and other voluntary culling reasons). Out of a total of 5133 culled cows, the proportions of culls, for each of these groups of reasons, were 12.4, 28.4, 2.7, 3.9, 4.6, 16.7, 5.9, and 25.4%, respectively. Cows culled for udder disorders left the herd earlier in lactation and were more frequently at parities 4–6 than cows culled for voluntary reasons. In contrast, cows culled for infertility were younger and culled later within lactation. They were also higher yielding cows than those culled for other reasons. Cows culled for lameness were similar to those of the voluntarily culling group. Cows culled for emergency reasons were more frequently younger cows in early lactation. Cows culled for other health disorders left the herd early in lactation, but at a higher parity than the voluntarily culled cows. These results suggest that most of the culls related to health could be contributing to economic loss. However, special priority should be given to reduce culling for reproductive problems, which is the most costly exit reason.     

Reproductive performance of Holstein dairy cows in Iran

The objectives of the present study were to describe the current reproductive parameters of Holstein dairy cows in Iran and to determine factors which have a significant effect on reproductive performance with emphasis on high-producing dairy cows. Five large Holstein dairy herds from the major milk production areas of Iran were selected for this study. Reproduction data including parity of dam, calving date, days to first service, days open, number of services, dry period, and occurrence of diseases for cows that calved from 2004 to 2007 were collected from the herds' databases. To determine the effects of year and season of calving, disease status, level of milk production, and parity of dam on reproductive parameters, the proc-mixed procedure in SAS software was used. Overall, data about 8,204 lactation were collected for the study. Results showed that mean (±SD) days open, calving interval, and days to first service for study herds were 134 (±89), 403 (±86), and 67 (±38) days, respectively. Conception rates at the first service and the overall service-conception rate were 41.6% and 41%, respectively. The level of milk production and diseases had significant negative effects on days open and service per conception (P < 0.05); statistical analysis showed that for every 100-kg increase in milk yield, days open will increase by about 0.3 days. However, no significant effect of level of productivity was observed on days to first service. The results of this study indicate that high milk production is a risk factor for decreasing fertility in Iran, like many other parts of the world.     

Depressed DHEA and increased sickness response behaviors in lame dairy cows with inflammatory foot lesions

Lameness is a multifactorial condition influenced by the environment, genetics, management and nutrition. Detection of lameness is subjective and currently limited to visual locomotion observations which lack reliability and sensitivity. The objective of this study was to search for potential biomarkers of inflammatory foot lesions that underlie most cases of lameness in dairy cows, with a focus on the sickness response and relevant endocrine, immune and behavioral changes. Serum and peripheral blood mononuclear cells (PBMC) were collected from eight sound and eight lame high-producing Holstein cows. Immune cell activation was investigated in PBMCs using a candidate gene approach in which the expression of pro-opiomelanocortin, interleukin-1beta, l-selectin, matrix metalloproteinase-9 and glucocorticoid receptor-alpha was measured via quantitative real time-RT-PCR. Endocrine changes were investigated by monitoring serum concentrations of cortisol and dehydroepiandrosterone (DHEA). Additionally, systematic behavioral observations were carried out to characterize a behavioral profile associated with a sickness response typical of this condition. Lame cows showed significantly lower eating (P=0.01) and ruminating (P=0.01) behaviors and higher incidence of self-grooming (P=0.04) compared to sound cows. Lame cows also showed a 23% decrease in serum DHEA (P=0.01) and 65% higher cortisol:DHEA ratio (P=0.06) compared to sound cows. However, no significant differences were found in candidate gene expression between lame and sound cows. In association with sickness behaviors, serum DHEA concentration and cortisol:DHEA ratio are promising objective indicators of inflammatory foot lesions in dairy cattle and may be useful as diagnostic targets for animals in need of treatment.     

Stillbirth parturition reduces milk production in Holstein cows

Stillbirth is defined as calf mortality shortly before, during, or shortly after parturition. Economic losses to the dairy industry in the U.S. just due to the loss of replacement heifers were estimated to be $125 million per year. Our objective in this study was to evaluate the effect of stillbirth on the dam's subsequent lactation. Data were collected from 20 farms in the U.S.A. (19 from NY, one from IN) from May 2005 until September 2006. Calving-ease scores (scale of 1-5; no problem and extreme difficulty, respectively) and stillbirths were recorded by farm personnel. We used 32,299 calvings for the final analysis where 6.5% of the calvings were stillbirths. The incidence of stillbirths for primiparous cows was 10.7% (of 11,891) and 4% (of 20,408) for multiparous cows. Stillbirth parturition significantly reduced milk production (-1.1 kg/day). The losses in milk production were evaluated in a generalized mixed linear model analysis. The daily milk production for cows with stillbirths was 34.2 kg, compared to 35.3 kg for the cows that had a live calf. Milk-production reduction was greatest early in lactation and declined afterwards. Economic losses from stillbirths include not just the lost calf, the reduced survival, and increased days open but also the decreased milk yield.     

Electroretinogram and visual-evoked potential measurements in Holstein cows

The electroretinogram (ERG) and flash visual-evoked potential (FVEP) were recorded from 25 Holstein cows in a clinical setting without dark adaptation. Latencies to the a and b waves of the ERG were measured bilaterally. The ERG recordings were between the lower eyelid of the stimulated eye and the vertex, with ground on the nuchal crest. Stimuli for ERG and FVEP were 1.5 flashes of white light/s. Recorded ERG were highly consistent and repeatable. The average latencies for the a and b waves were 14 and 30 ms; the mean ab amplitude was 43 microV. The FVEP were recorded bilaterally between the middle of the interocular line and the midpoint of the nuchal crest, with ground on the vertex. The FVEP measurements included latencies to 5 alternating positive and negative peaks (P1, N1, P2, N2, and P3) and 4 peak-to-peak amplitudes (P1 to N1, N1 to P2, P2 to N2, and N2 to P3). The P2 peak was consistently the most prominent. Average latencies for the 5 peaks were 46, 64, 86, 106, and 137 ms for P1, N1, P2, N2, and P3, respectively. The FVEP peak-to-peak amplitudes had a high variability.     

奶牛子宫复旧的B-超影像学研究

应用Ｂ型实时超声断层扫描仪（Ｂ－ 超），对奶牛子宫复旧过程进行研究。对３８ 头中国荷斯坦奶牛，用Ｂ－ 超和连续检查法监测了子宫复旧过程。结果，经连续直肠检查法监测，受试牛子宫孕角、空角和子宫颈复旧的平均时间分别为（３７ ．４±３．１）、（３１．４ ±４．９）和（３６．８ ±４．９） ｄ；用Ｂ－ 超监测则为（３５ ．５±４．５） 、（３０．８ ±５．９）和（３７．５ ±５．０）ｄ。并且Ｂ－超监测还发现，分娩当天子宫肌层平均厚度为１．６５ ｃｍ ，产后２３ ｄ 时减少到１．３５ｃｍ ；产后第５ 天在超声影像上可见子宫内膜，平均厚度为０ ．３ ｃｍ ，第１５ 天为０ ．６ ｃｍ ，而到产后２３ ｄ 平均增厚到１．０２ ｃｍ ，子宫复旧完成时，子宫壁平均厚度为１ ．０ ｃｍ ；两子宫角的横切面轮廓清晰，大小基本相同，超声影像变白。研究表明Ｂ－ 超监测奶牛子宫复旧过程是可行的。     

Genetic parameters of lifetime performance traits in Holstein cows

SUMMARY: Heritabilities, genetic and phenotypic correlations among lifetime yields of milk, fat and protein, herdlife, productive life and number of lactations initiated in the herd were estimated from records of 44,933 progeny of 427 young and 119 proven Holstein sires in 1949 herds using a multivariate Reml technique to fit a sire model with relationships among young sires. Proven sires were fitted as fixed effects. Heritabilities of lifetime traits ranged from 0.005 to 0.030, suggesting little scope for direct selection for lifetime performance traits. Productive life had highest genetic correlation with lifetime fat yield (0.934), but correlations with lifetime milk and protein yields were smaller and similar (0.773 and 0.772). The number of lactations also had highest genetic correlation with lifetime fat yield. ZUSAMMENFASSUNG: Genetische Parameter von Lebensleistungsmerkmalen bei Holsteinkühen Heritabilit?tswerte, genetische und ph?notypische Korrelationen zwischen Lebensleistungsmerkmalen für Milch, Fett und Protein, Lebensdauer, produktive Zeit und Zahl Laktationen wurden won 44933 Nachkommen von 427 jungen und 119 nachkommenschaftsgeprüften Holsteinstieren in 1949 Herden mittels einer multivariablen REML-Technik gesch?tzt, die auf einem Vatertiermodell mit Verwandtschaft zwischen den jungen Stieren beruhte. Geprüfte Stiere wurden als fixe Effekte im Modell berücksichtigt. Heritabilit?tswerte dieser Merkmale rangieren von 0.005 bis 0.03, so da? wenig Aussichten für Erfolg direkter Selektion auf Lebensleistungsmerkmale besteht. Die L?nge des produktiven Lebens hatte die h?chste genetische Korrelation mit Lebensfettmenge (0.934), aber die Korrelationen mit Milch- und Protein-Lebensleistung waren kleiner und ?hnlich (0.773 und 0.772). Die Zahl der Laktationen hatte die h?chste genetische Korrelation mit der Lebensfettmenge.     

Risk factors for metritis in Danish dairy cows

A retrospective longitudinal study of metritis was conducted in Denmark on data collected during 1993-1994. Data on herd size, breed, parity, and treatment of disease were obtained from the Danish Cattle Database. Management and production-facility data were collected using a questionnaire, conducted as a telephone interview in 1994. The study included 2144 herds from three regions in Denmark (102,060 cows). Herd-level variables included were: herd size, housing, flooring, grazing, calving measures, and calving supervision. Cow-level variables were: parity, breed, calving season and whether the cow had been treated by a veterinarian for dystocia or the diseases: retained placenta, reproductive disease, ketosis, milk fever, or dry cow mastitis.Marginal multivariable logistic-regression analyses were performed. The cow with highest odds of metritis was a first or greater than or equal to third parity cow, of large breed, that calved during November-April, in a zero-grazing herd. The cow had been treated for dystocia, retained placenta, and at least one other reproductive disease, but not for ketosis.     

Lifetime performances in Carora and Holstein cows in Venezuela

A study was conducted in the Central-western region of Venezuela to investigate the lifetime performances of 7918 Carora and 3501 Holstein cows under two different levels of management (low and high) and covering a period from 1961 to 1995. Traits analysed were: herd life, productive life, number of calvings, lifetime milk yield, days in lactation over all lactations and daily milk yield. In Carora cows born from 1961 to 1986 a decrease in herd life, productive life and number of calvings was observed, whereas cows born between 1971 and 1972 showed the lowest lifetime productive traits. Performances of Holstein cows born in the 1981–1986 period were analysed and all traits decreased during this time period. In low level herds, Holsteins remained longer (98.5 months vs. 83.3 in herd life; 69.5 vs. 54.3 months in productive life) and had higher lifetime yield (20 925 vs. 18 589 kg) than those in high level herds, but daily milk yield was lower (8.4 vs. 11.0 kg/day). All lifetime performances were higher for Carora cows under the high level management: 116.8 vs. 112.1 months of herd life, 81.8 vs. 77.1 months of productive life, 5.8 vs. 5.2 calvings, 1616 vs. 1299 days of lactation, 16 194 vs. 11 912 kg of milk over all lactations and 6.5 vs. 4.6 kg milk/day. Survival estimates for year of birth were more variable in Holsteins than in Carora cows. Management influenced survival in Holsteins only, the low level showing higher values.     

Genetic evaluation of heat tolerance in Holstein cows in Japan

We used test‐day records and daily records from provincial weather stations in Japan to evaluate heat tolerance (HT) in Holstein cows according to a random regression test‐day model. Data were a total of 1,641,952 test‐day records for heritability estimates and 17,245,694 test‐day records for genetic evaluation of HT by using milk yield and somatic cell score (SCS) in Holstein cows that had calved for the first time in 2000 through 2015. Temperature–humidity index (THI) values were estimated by using average daily temperature and average daily relative humidity records from 60 provincial Japanese weather stations. The model contained herd–test‐day, with lactation curves on days in milk within month–age group as a fixed effect. General additive genetic effect and HT of additive genetic effect were included as random effects. The threshold value of THI was set to 60. For milk yield, estimated mean heritabilities were lower during heat stress (THI = 78; 0.20 and 0.28) than when below the heat stress threshold (THI ≤ 60; 0.26 and 0.31). For SCS, heritability estimates (range 0.08–0.10) were similar under all heat stress conditions. Genetic trends of HT indicated that EBVs of HT are changing in an undesirable direction.     

对当前中国荷斯坦牛育种工作的建议

改革开放以来,我国奶牛养殖业得到了突飞猛进的发展。2003年我国奶牛存栏数已达到893.2万头,牛奶总产达到1746.3万t,人均占有牛奶量达到12kg,取得了可喜的成绩。但是,成年母牛平均单产仅有3200余kg,同国际奶牛业发达国家平均9000～10000kg相比较,差距很大,仅是人家的三分之一左