Effect of several doses of zeolite A on feed intake,energy metabolism and on mineral metabolism in dairy cows around calving

The object of the present study was to determine the influence of different zeolite A doses on dry matter intake (DMI) and mineral metabolism, and to evaluate an optimum dosage for preventing hypocalcaemia. Eighty pregnant dry cows were assigned to four groups (I–IV). They were fed a total mixed ration (TMR) ad libitum. Groups II, III and IV received an average daily dose of 12, 23 and 43 g zeolite A/kg DM for the last 2 weeks prepartum. Individually DMI was recorded daily. Blood and urine samples were taken before, during and after zeolite A supplementation. Serum was analysed for Ca, Mg, P_i, K, non‐esterified fatty acids and β‐hydroxybutyrate (BHB). Urine was analysed for Ca, Mg, P_i, K and net acid‐base excretion (NABE). After calving, milk yield (fat corrected milk) and milk composition were determined. During zeolite A supplementation, mean DMI of Group IV (7.3 ± 1.3 kg/cow/day) was significantly lower compared to Groups I–III (10.1, 10.9, 9.5 kg/cow/day). The reduced feed intake of Group IV resulted in significantly increased BHB as well as decreased NABE after calving. Zeolite A supplementation in higher doses (III and IV) had a stabilizing effect on Ca metabolism around calving for older cows, whereas cows in Groups I and II showed a subclinical hypocalcaemia. The mean serum Mg concentration decreased significantly in older cows in Group IV at calving. The mean P_i concentration in cows of Group IV decreased into ranges of hypophosphataemia already 1 week after beginning of zeolite A feeding. The mean DMI postpartum as well as the milk yield was not affected by zeolite A supplementation. Feeding of 23 g zeolite A/kg DM TMR prepartum proved to be an adequate dosage for reducing subclinical hypocalcaemia frequency without significant effects on feed intake and P_i concentration in serum.     

从饲喂策略考虑提高母猪泌乳期采食量

母猪泌乳期高自由采食量(VFI)是其繁殖性能正常发挥的保证。为了提高母猪泌乳期VFI,文中分析了母体因素如品种、基因、带仔数、体况等对VFI的影响,提出着重从全繁殖周期饲喂策略考虑,以提高母猪泌乳期VFI。     

A simulation model for predicting the voluntary feed intake of a growing pig

Abstract

The main goal of this simulator is to predict voluntary feed intake based on the effects of temperature and stocking density. The model indicates the limiting factors relative to diet (protein, energy or ash), housing environmental conditions and stocking density. The concepts of compensatory protein growth, correction of lipid growth, the desired feed intake to meet energy, protein and ash requirements, and influences of stocking density, genotype and sex are also introduced in this model. This study draws a flow chart and steps to predict feed intake of a growing pig to make it clear how the model works. The model simulates the outcomes of feed intake, energy and protein requirements for maintenance, the energy cost for cold thermogenesis, and protein and lipid retention on a daily basis until slaughter weight. This model was also validated by comparison with published experiments.     

甘油代替大麦对泌乳中后期奶牛采食量、产奶量和乳质量的影响

文章旨在确定在不影响牛奶产量、牛奶成分、乳脂肪酸组成和牛奶感官质量的情况下,用不同水平甘油代替大麦对泌乳中后期奶牛的影响。试验选择了40头荷斯坦奶牛,采用4×4拉丁方试验设计。在部分混合日粮中,粗甘油替代大麦的含量分别为日粮干物质的0、6%、12%和18%。每天记录个体产奶量、采食量和挤奶频率,每周分析牛奶成分。对新鲜牛奶和贮藏7 d的牛奶样品进行感官分析。部分混合日粮的摄入量随甘油添加水平由0升高至12%,增加近1 kg,甘油由12%升高至18%,减少约1 kg。甘油水平由0升高至6%时,精料摄入量下降0.5 kg。随着日粮中甘油比例的增加,牛奶产量呈线性下降(P<0.05),而牛奶中的脂肪和蛋白质含量呈上升趋势(P=0.08),导致能量校正乳水平随甘油水平的升高表现为二次曲线效应,其中6%甘油组产量最高,18%甘油组产量最低。蛋白质和乳糖产量随日粮中甘油比例的增加线性下降(P<0.05)。随着日粮甘油比例的增加,牛奶中棕榈酸、油酸、亚油酸、亚麻酸和共轭亚油酸的比例线性下降(P<0.05),而短链和中链脂肪酸的比例大部分呈上升趋势。综上所述,甘油作为一种能量饲料可以在不影响牛奶品质的前提下,在泌乳中后期奶牛日粮中替代大麦的水平高达18%。但日粮甘油水平超过12%时可能会降低能量校正乳的产量。     

Genetic parameters for residual energy intake and energy conversion efficiency in Nordic Red dairy cattle

Abstract

Our aim was to estimate the genetic parameters of residual energy intake (REI) and energy conversion efficiency (ECE), and their relationships with milk, feed intake and body weight (BW) and condition in Nordic Red dairy cattle with data from 400 animals. These data were analysed with repeatability and random regression models. The highest heritabilities for energy efficiency traits were obtained in the beginning and the end of the 30 week lactation period (0.21–0.40). The results suggest that the energy efficiencies in early- and mid-lactation periods are partially different traits. The genetic correlations of REI were moderate to high and positive with the other studied traits, and high and positive for ECE with milk, but moderate to low and negative with dry matter intake, BW and body condition score. Further improvements are still needed in modelling the energy efficiency traits of cows during lactation.     

放牧条件下乳用伊犁马采食量的初步研究

2013年8-10月,采用模拟采食法、群牧差额法、内外指示剂结合法在昭苏马场草甸草地上进行了放牧条件下乳用伊犁马采食量的测定。结果表明,1)同种测定方法不同月份之间测定的乳用伊犁马干物质采食量差异不显著(P0.05)。2)模拟采食法测得的干物质采食量为12.79 kg·15 h-1·匹-1,群牧差额法测得为16.39kg·d-1·匹-1,内外指示剂结合法测得为13.28 kg·d-1·匹-1。3)群牧差额法与内外指示剂结合法测定的乳用伊犁马干物质采食量之间差异不显著(P0.05),初步确定乳用伊犁马平均干物质采食量为14.83 kg·d-1·匹-1。     

Physically effectiveness of beet pulp‐based diets in dairy cows as assessed by responses of feed intake,digestibility, chewing activity and milk production

Nine multiparous Holstein cows (DIM = 56 ± 5 day) were randomly assigned to three experimental diets containing fine‐dried (T1), normal‐dried (T2) and pelleted (T3) beet pulp (BP) at 12% on a dry matter basis in a 3 × 3 change over design in three 21 day periods to evaluate the effects of three types of BP. Bulk density, functional specific gravity and water‐holding capacity of ration and intake were similar, but intake of physically effective fibre was different among treatments. Without significant differences, nutrients' digestibility in T1 trended to be higher than T2 and T3. Ruminal liquid pH and N‐NH3 concentration were lower in T1 and higher in T3 than T2. Grinding and pelleting of BP increased and decreased volatile fatty acid concentration respectively. Grinding decreased acetate and propionate and increased butyrate and lactic acid. In contrary to pelleting, grinding of BP increased the particulate ruminal passage rate, but decreased ruminal mean retention time and lower compartment mean retention time. Pelleting of BP decreased ruminal passage rate, but increased ruminal mean retention time and lower compartment mean retention time. Grinding increased 5.64, 5.9 and 5.8% eating time, rumination and total chewing activity in comparison with normal BP respectively. Pelleting increased 2.7%, 16.3% and 10.0% eating time, rumination and total chewing activity in comparison with T2 respectively. Milk yield had no significant difference, but milk yield adjusted to 4% fat, and milk fat (kg/day), fat, protein, casein and total solid of milk (%) were affected by the treatments. Results from this experiment show that based on milk fat assay, grinding did not reduce effectiveness of BP, but pelleting significantly increased effectiveness of BP. In addition, based on total chewing activity, grinding did not reduce physically effectiveness of BP, but pelleting of BP increased its physically effectiveness.     

Evaluation of two dairy herd reproductive performance indicators that are adjusted for voluntary waiting period

Background

Overall reproductive performance of dairy herds is monitored by various indicators. Most of them do not consider all eligible animals and do not consider different management strategies at farm level. This problem can be alleviated by measuring the proportion of pregnant cows by specific intervals after their calving date or after a fixed time period, such as the voluntary waiting period. The aim of this study was to evaluate two reproductive performance indicators that consider the voluntary waiting period at the herd. The two indicators were: percentage of pregnant cows in the herd after the voluntary waiting period plus 30 days (PV30) and percentage of inseminated cows in the herd after the voluntary waiting period plus 30 days (IV30). We wanted to assess how PV30 and IV30 perform in a simulation of herds with different reproductive management and physiology and to compare them to indicators of reproductive performance that do not consider the herd voluntary waiting period.

Methods

To evaluate the reproductive indicators we used the SimHerd-program, a stochastic simulation model, and 18 scenarios were simulated. The scenarios were designed by altering the reproductive management efficiency and the status of reproductive physiology of the herd. Logistic regression models, together with receiver operating characteristics (ROC), were used to examine how well the reproductive performance indicators could discriminate between herds of different levels of reproductive management efficiency or reproductive physiology.

Results

The logistic regression models with the ROC analysis showed that IV30 was the indicator that best discriminated between different levels of management efficiency followed by PV30, calving interval, 200-days not-in calf-rate (NotIC200), in calf rate at100-days (IC100) and a fertility index. For reproductive physiology the ROC analysis showed that the fertility index was the indicator that best discriminated between different levels, followed by PV30, NotIC200, IC100 and the calving interval. IV30 could not discriminate between the two levels.

Conclusion

PV30 is the single best performance indicator for estimating the level of both herd management efficiency and reproductive physiology followed by NotIC200 and IC100. This indicates that PV30 could be a potential candidate for inclusion in dairy herd improvement schemes.     

Effects of forage-to-concentrate ratio in prepartum diet on the dry matter intake and milk yield of periparturient cows during hot weather

The objective of this experiment was to study the effect of prepartum diets on dry matter intake (DMI) around parturition and on milk production in early lactation during a hot summer. Nine cows due to calve in July or August were assigned to two groups and fed either control (group C; four cows) or high‐concentrate (group H; five cows) diets to meet 110% of their energy requirements from 18 days before the expected calving date to parturition. The proportion of concentrate in the control diet was 35%, and that in the high‐concentrate diet was 45%. For 21 days after parturition, all cows were fed the same diets for lactation ad libitum. The DMI of cows in group H almost met their energy requirements. In group C, the DMI was decreased relative to group H and the concentration of plasma non‐esterified fatty acids was significantly higher (P < 0.05) before parturition. Therefore, the cows in group C were thought to be energy deficient before parturition. After parturition, there were no significant differences in DMI between the two groups. The milk yield of cows in group H tended to be higher than that of cows in group C at 21 days after parturition. Milk protein yield was significantly higher (P < 0.05) in group H 21 days after parturition relative to group C. There were no significant differences in milk composition between the two groups.     

Effect of parity number on the dry matter intake of dairy cows during the first week after calving

We investigated the effect of parity number on the dry matter intake (DMI) of cows during the first week after calving. Eighty‐three cows were evaluated from 14 days before to 7 days after calving. DMI and milk yield were measured for 7 days after calving, and the calving score was measured. Blood samples were collected throughout the experiment. The average DMI during the first week after calving was reduced in the first‐lactation heifers and high‐parity number cows. A quadratic relationship between the parity number and the DMI was observed. The first‐lactation heifers had lower prepartum serum total protein (TP) concentration and milk yield, higher prepartum serum nonesterified fatty acid (NEFA) concentration and calving score than the multiparous cows. The recovery rate of serum calcium (Ca) after calving was slow in the cows in the parity 6. The DMI was positively affected by the serum Ca concentration after calving, milk yield, and prepartum serum TP concentration and was negatively affected by the calving score and prepartum serum NEFA concentration. We conclude that the DMI immediately after calving tends to be lower in first‐lactation heifers and high‐parity number cows, but factors that reduce the DMI differ according to parity number.     

Herbage intake and ruminal digestion of dairy cows grazed on perennial ryegrass pasture either in the morning or evening

This study aimed to clarify diurnal fluctuations of herbage intake, ruminal fermentation of herbage carbohydrates and proteins, and digesta particulate weight in the rumen of grazing dairy cows. Six ruminally cannulated, non‐lactating dairy cows were grazed on perennial ryegrass/white clover pasture either in the morning (04.00 to 08.00 hours) or the evening (16.00 to 20.00 hours). Cows grazed in the evening spent more time (P < 0.01) and consumed more herbage (P < 0.01) compared with cows grazed in the morning. Higher (P < 0.05) daily mean concentrations of total volatile fatty acid, propionate and n‐butyrate in rumen fluid were observed for cows grazed in the evening compared with cows grazed in the morning. Although cows grazed in the evening ingested more crude protein compared with cows grazed in the morning, no significant difference in NH₃‐N concentration in rumen fluid was observed between them. The ratio of purine‐derivative concentration to creatinine concentrations was higher (P < 0.01) in the urine of cows grazed in the evening than in cows grazed in the morning. These results clearly indicated that evening grazing was advantageous for dairy cows compared with morning grazing, in terms of ruminal fermentable energy intake and nitrogen utilization efficiency.     

Tail docking and beliefs about the practice in the Victorian dairy industry

OBJECTIVE: To determine the occurrence of tail docking and beliefs about the practice in the Victorian dairy industry. DESIGN: Survey responses were analysed using chi-square tests and by correlation and regression analyses to determine associations between husbandry practices and beliefs and to identify possible predictive variables in relation to docking. PROCEDURE: A survey of the occurrence of docking and beliefs about the practice was conducted in 1997 using face-to-face interviews of 313 respondents at 234 Victorian dairy farms. RESULTS: On average, 35% of dairy farms routinely docked cattle. The practice varied from 11 to 63% in different regions and 12% of stud farms docked their cows. Rubber rings were used on 75% of farms and the average age of the cow at docking was 18 months. Twenty-two percent of cows were docked at a level above the top of the udder and 54% were docked level with the top of the udder. Respondents that docked believed that milking was finished quicker, the risks of leptospirosis for the operator and mastitis for the cow were reduced, the cows were easier to handle, fly numbers were reduced and milk quality was improved. There was a general belief that intact tails could cause significant discomfort to the operator and that docking resulted in acute but not chronic pain. CONCLUSIONS: Docking is an entrenched practice in the Victorian dairy industry. Those farmers who docked generally believed that it was a highly desirable farming practice with particular benefits for the operator.     

Relationship of rumen fill and fermentation to diurnal and seasonal variation of herbage intake in dairy cows grazed on perennial ryegrass pasture

To clarify the effect of digesta weight in the reticulorumen on diurnal and seasonal fluctuations in herbage intake, six ruminally cannulated, non‐lactating dairy cows were grazed on perennial ryegrass/white clover pasture during morning and evening sessions in spring and autumn. The digesta weight of fresh matter, dry matter (DM) and fiber in the reticulorumen at the beginning and the end of each grazing session was lower in spring than in autumn (P < 0.01). Although the digesta weight was similar between the sessions at the beginning of grazing, it was greater for the evening than for the morning at the end of grazing (P < 0.01). The large particles proportion in the digesta was lower for the morning than the evening (P < 0.01), and it was lower in spring than in autumn (P < 0.01). The concentrations of volatile fatty acids in rumen fluid were generally higher in spring compared with autumn. The herbage DM intake during the evening was greater compared with the morning in both seasons (P < 0.01). However, there was no difference in herbage DM intake between seasons. The results showed that the rumen digesta fill was not the sole factor explaining diurnal and seasonal variation of herbage intake in grazing dairy cows.     

Relationship between fat accumulation in the liver and energy intake, milk fat yield and blood metabolites in dairy cows

In the present study, 42 multiparous Holstein cows were used to investigate the relationship between fat accumulation in the liver and dry matter intake, milk yield and blood metabolites. Based on the percentage of fat in the liver cell at 2 weeks post‐parturition, the cows were classified into three groups. These groups were: (i) less than 10% of fat (normal group, n = 29); (ii) 10–20% of fat (mild group, n = 6); and (iii) more than 20% of fat (moderate group, n = 7). The bodyweight of the moderate group was high (771 kg) before calving. The sufficiency rates of total digestible nutrients (TDN) were remarkably decreased (approximately 65%) in early lactation. The milk fat yield and milk fat composition of the moderate group were higher (P < 0.05) than the other groups at 1 and 2 weeks post‐parturition. It was suggested that non‐esterified fatty acids (NEFA) mobilized from adipose tissues was directly used by the mammary gland for synthesis of milk fat. The percentage of bromsulfalein (BSP) retention of the moderate group was high (21.1%) at 30 min, and it showed that the BSP clearance function was significantly decreased. The concentrations of NEFA, β‐hydroxybutyric acid and glucose were appropriate indicators of energy status; however, aspartate aminotransferase, γ‐glutamyl transpeptidase and total bilirubin were not sensitive indicators of a moderate fatty liver. Thus, high‐yielding cows that calve in an overweight condition are more likely to develop excessive fat accumulation in the liver because of great mobilization from adipose tissues post‐parturition. In cows with a moderately fatty liver, a decrease in TDN sufficiency rates, an increase of milk fat yield and a reduction of liver function were observed in early lactation. The increase of serum NEFA and milk fat composition resulting from mobilization of adipose tissues helped to diagnose moderate fatty liver.     

中草药饲料添加剂在奶牛生产中的应用

本文针对中草药对奶牛泌乳性能、抗热应激、免疫机能及繁殖等方面的影响作一综述。     

A meta-analytical evaluation of the effects of high-salt water intake on beef cattle

Adequate drinking water is essential to maintain acceptable production levels in beef cattle operations. In the context of global climate change, the water scarcity forecasted for the future is a growing concern and it would determine an increase in the use of poorer quality water by the agricultural sector in many parts of the world. However, consumption of high-salt water by cattle has consequences often overlooked. A meta-analysis was carried out to assess the impact of utilizing high-salt water on dry matter (DMI) and water intake (WI), and performance in beef cattle. The dataset was collected from 25 studies, which were conducted between 1960 and 2020. Within the dataset, the water quality was divided into three categories according to the ratio of sulfates (SO4) or sodium chloride (NaCl) to total dissolved solids (TDS): 1) TDS = all studies included (average SO4:TDS = 0.4); 2) NaCl = considered studies in which water salinity was dominated by NaCl (average SO4:TDS = 0.1); and 3) SO₄ = considered studies in which water salinity was dominated by SO₄ (average SO₄:TDS = 0.8). Results showed that DMI and WI were negatively affected by high-salt water consumption, although the magnitude of the effect is dependent on the type of salt dissolved in the water. There was a quadratic effect (P < 0.01) for the WI vs. TDS, WI vs. NaCl, DMI vs. TDS, and DMI vs. NaCl, and a linear effect (P < 0.01) for WI vs. SO₄ and WI vs. SO₄. Average daily gain (ADG) and feed efficiency (FE) were quadratically (P < 0.01) affected by high-salt water, respectively. This study revealed significant negative effects of high-salt water drinking on beef cattle WI, DMI, and performance. However, the negative effects are exacerbated when cattle drink high-sulfate water when compared with high-chloride water. To the best of our knowledge, this is the first approach to evaluate animal response to high-salt water consumption and could be included in the development of future beef cattle models to account for the impact of water quality on intake and performance. In addition, this meta-analysis highlights the need for research on management strategies to mitigate the negative effects of high-salt water in cattle.     

Effect of timing and type of supplementary grain on herbage intake,nitrogen utilization and milk production in dairy cows grazed on perennial ryegrass pasture from evening to morning

The present study aimed to clarify the effect of timing and type of supplementary grain in grazing dairy cows on herbage dry matter intake (HDMI), nitrogen utilization and milk production. Eight lactating cows were allowed to graze from evening to morning during three seasonal periods (spring, summer, autumn). They were randomly allocated to four treatments (timing: pre‐ (Pre) or post‐grazing (Post), for large grain allotments consisting of 75% of daily grain offered; grain type: barley or corn) in 4 × 4 Latin square designs in each period. In the spring period, HDMI was greater for cows fed corn than those fed barley (P = 0.005), whereas cows in the Pre treatment had a similar HDMI, higher (P = 0.049) urinary purine derivative concentration and greater (P = 0.004) milk yield compared with cows in the Post treatment. In the summer and autumn periods, timing treatments did not affect HDMI, nitrogen utilization or milk production, but cows supplemented with barley had higher urinary purine derivatives concentration (P < 0.05) and milk yield (P < 0.05) compared with those supplemented with corn. The results indicate that large grain allotments immediately before evening grazing during early grazing seasons increased ruminal microbial protein synthesis and milk production without reducing HDMI regardless of grain type.     

Evaluation of three different patterns of feed intake during early lactation in lactating sows

Forty‐five multiparous sows (Landrace × Yorkshire; parity: 3.58 ± 1.30) were used to determine the effects of three patterns of feed intake during early lactation on the performance of lactating sows. Experimental treatments were as follows: IFI‐1.4, the amount of feed increased by 1.4 kg per day for the first 5 days post‐farrowing, followed by ad libitum feeding until weaning; IFI‐1.0, the amount of feed increased by 1.0 kg per day for the first 7 days post‐farrowing, followed by ad libitum feeding until weaning; IFI‐0.7, the amount of feed increased by 0.7 kg per day for the first 10 days post‐farrowing, followed by ad libitum feeding until weaning. The number of live piglets at birth/litter in three dietary treatments was 11.50, 10.07, and 10.85, respectively. Sows in the IFI‐1.4 treatment had lower backfat loss during lactation, greater daily feed intake during days 1–6, 7–12, and 1–24 compared with those in the IFI‐0.7 treatment (p < .05). The litter weaning weight, litter weight gain, and average litter daily gain in the IFI‐1.4 treatment were greater compared with those in the IFI‐0.7 treatment (p < .05). In conclusion, the results indicated that the IFI‐1.4 feed intake pattern allowed lactating sows and their litters to obtain optimal performance.     

Simultaneous Bayesian estimation of genetic parameters for curves of weight,feed intake,and residual feed intake in beef cattle

Rates of gain and feed efficiency are important traits in most breeding programs for growing farm animals. The rate of gain (GAIN) is usually expressed over a certain age period and feed efficiency is often expressed as residual feed intake (RFI), defined as observed feed intake (FI) minus expected feed intake based on live weight (WGT) and GAIN. However, the basic traits recorded are always WGT and FI and other traits are derived from these basic records. The aim of this study was to develop a procedure for simultaneous analysis of the basic records and then derive linear traits related to feed efficiency without retorting to any approximation. A bivariate longitudinal random regression model was employed on 13,791 individual longitudinal records of WGT and FI from 2,827 bulls of six different beef breeds tested for their own performance in the period from 7 to 13 mo of age. Genetic and permanent environmental covariance functions for curves of WGT and FI were estimated using Gibbs sampling. Genetic and permanent covariance functions for curves of GAIN were estimated from the first derivative of the function for WGT and finally the covariance functions were extended to curves for RFI, based on the conditional distribution of FI given WGT and GAIN. Furthermore, the covariance functions were extended to include GAIN and RFI defined over different periods of the performance test. These periods included the whole test period as normally used when predicting breeding values for GAIN and RFI for beef bulls. Based on the presented method, breeding values and genetic parameters for derived traits such as GAIN and RFI defined longitudinally or integrated over (parts of) of the test period can be obtained from a joint analysis of the basic records. The resulting covariance functions for WGT, FI, GAIN, and RFI are usually singular but the method presented here does not suffer from the estimation problems associated with defining these traits individually before the genetic analysis. All the results are thus estimated simultaneously, and the set of parameters is consistent.     

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.