Journal of Animal Production, Print ISSN: 2008-6776., Online ISSN: 2382-994X

Abstract Objective: Heat stress in dairy cows is a common problem that affects metabolic balance, transition period management indices, and postpartum health, particularly in hot and dry areas, such as Isfahan province, Iran. This study aimed to evaluate the effects of season (summer vs. winter) and the severity of heat stress on calving-related management indices, body condition, metabolic disorders, serum calcium status, and reproductive outcomes in Holstein dairy herds in Isfahan province.
Method: The study was conducted as a completely randomized design in four industrial Holstein dairy herds in Isfahan Province, Iran, during summer and winter seasons, with 855 dairy cows. Daily meteorological data were recorded to calculate the temperature–humidity index (THI). Body condition score (BCS) at calving, gestation length, dry period length, colostrum yield, incidence of metabolic disorders (retained placenta, metritis, hypocalcemia, and ketosis), culling rate up to 60 days postpartum, and conception rate at first AI were recorded. Serum calcium concentration was measured at calving and on day 3 postpartum, and serum beta-hydroxybutyrate concentration was measured on day 10 postpartum. The data were analyzed with appropriate statistical models, considering the effect of season, herd, parity, and their interactions. All statistical assumptions including normality of residuals and homogeneity of variances were tested and confirmed before final analysis.
Results: THI values ranged from 74 to 82 during the summer, suggesting moderate to severe heat stress. Gestation length was shorter in primiparous cows than in multiparous cow within each herd (P<0.05). Body condition score at calving was influenced by herd management (P<0.05). Colostrum yield was lower in multiparous cows compared to primiparous cows (P<0.05), and tended to decrease during the summer season (P=0.07). Dry period length also decreased during the summer (P<0.05). The incidence of retained placenta and metritis was influenced by season, herd, and parity, with the highest incidence in the winter season (P<0.05). While dystocia was higher in summer (P<0.05), serum calcium concentration was lower in summer than in winter (P<0.05). The prevalence of hypocalcemia and ketosis, especially in multiparous cows, was also higher in summer (P<0.05). The culling rate up to 60 days postpartum was higher in Herd C during both seasons.
Conclusion: Findings of this study showed that herd management and lactation parity differences were significant factors in the occurrence of metabolic disorders and calving-related factors; heat stress reduced the occurrence of retained placenta and metritis, but limited dry period length and colostrum yield in dairy cows.

Abstract Introduction Mastitis is one of the most frequent and costly diseases of the dairy cattle industry and causes many economic losses, which negatively affects milk yield and composition, fertility, longevity and welfare of cows. The best solution for reducing the economic and biological consequences is early and accurate prediction of mastitis based on indicator factors. So far, various statistical methods have been used to predict mastitis such as linear and multiple regression, and threshold models. Machine learning is another method that has recently widely been used to predict farm profitability, reproductive traits, longevity and abortion in dairy cow. Machine learning is defined as a set of methods for automatically finding patterns in data and then using those patterns to predict possible future data.

Material and Methods In this research, the performance of four machine learning algorithms including random forest, decision tree, Naïve Bayes and logistic regression and two sampling methods, over-sampling and under-sampling, were compared to predict risk of clinical mastitis based on data collected in two Holstein dairy herds in Isfahan province. Final dataset included 393504 records on cows calved during 2007 to 2017 of which 13653 cases (3.47%) were infected and 379851 cases (96.53%) were healthy. Factors related to mastitis, including parity, daily milk production, calving

Abstract The aim of this study was to estimate the economic values for residual feed intake and some production and performance traits in Iranian Holstein dairy cow. For this purpose, trait by trait or multiple traits of bio-economic modeling along with production and economic data were used. These data were collected from seven large herds of dairy cows in 2020. The economic values of the residual feed intake was calculated in four different age groups. The diets of different groups were formulated using CNCPS software. Index economic weights (multiplication of the economic values by discounted genetic expressions, in Rial and one cow per year) on average at the level of the studied farms were estimated to be IRR 14280 per kg of milk yield; IRR 291060 per kg of fat yield; IRR 232260 per kg of protein yield; IRR - 790860 per kg of residual feed intake; IRR 702588 per month of longevity and IRR- 113820 per day of days open. The sensitivity analysis showed that the price of concentrate ingredients has a greater effect on the economic value of the residual feed intake than of forage ingredients. In the genetic- economic analysis, the milk production with a relative emphasis of 50 percent was the most important trait in the breeding of Iranian dairy cows, while the relative emphasis on feed efficiency was only about 5 percent. The results of this research provide valuable information for economic values of traits that can be used to complete the national selection index and cost-benefit analysis.

Abstract Effect of sodium bicarbonate and pHmax buffer supplement on milk fat synthesis under milk fat depression conditions, using of 24 Holstein lactating cows were investigated in a completely randomized block design. Milk fat depression was induced in all cows for 10 d by feeding a diet containing high levels of starch. The experiment was conducted in two periods including: first period (day 1 to 20), allocation of cows to the treatments 1) control, 2) basal diet + 0.8% pHmax and 3) basal diet + 0.8% sodium bicarbonate and in the second period (days 21 to 30), all cows were fed the control diet. Buffer supplements increased milk fat concentration, without affecting dry matter intake, milk yield, and milk protein and lactose concentrations. The concentration of total trans fatty acids decreased in the experimental treatments compared to the control. The trans -10: trans -11 ratio was lower in cows receiving the buffer supplements compared with cows receiving the control, which indicating the effect of these compounds on the improvement of milk fat synthesis by stimulating normal fatty acid biohydrogenation pathways in the rumen. Addition of buffer supplements increased milk fat synthesis, which persisted for one week after cessation of mentioned compounds. Therefore, using of sodium bicarbonate and pHmax can maintain milk fat in dairy cows fed with diets containing high starch and under milk fat depression conditions. Also, using of pHmax reduces the costs of using common buffer compounds such as sodium bicarbonate.

Abstract The objective of this experiment was to study the effect of diet containing high (40.7 %) non fibrous carbohydrates on some inflammatory and native immunity related genes expression in lactating Jersey cows. Seven lactating multiparous (2.5 ± 0.5) Jersey cows with 71 ± 3 days in milk and 28 ± 6.6 kg of average milk production were used. All cows received a control diet containing low (34.3 percentage of dry matter) non fibrous carbohydrates content for the first 14 days and then were were switched to a diet containing high (40.7 percentage of dry matter) non fibrous carbohydrates content for one week. Blood samples were collected on day 0 (After 14 days of feeding control diet) and days 4 and 7 after feeding high NFC diet. Relative gene expression of seven genes (IL1-β, TNF-α, MNDA, CD74, TLR2, SELECTIN, TGF1-β) were measured. The results showed that gene expression of the pro-inflammatory cytokines (IL1-β and TNF-α) and anti-inflammatory proteins (MNDA, D74, TLR2, SELECTIN, TGF1-β) was down regulated during feeding of high NFC diet (p < 0.05). These data indicated that feeding a high non-fibrous carbohydrates diet caused inflammation and affected immunity system in lactating Jersey cows.

Abstract The objective of present study was to investigate the effect of different levels of sesame meal in early lactation cow's ration on dry matter intake, milk
yield and composition, apparent digestibility of nutrients and blood metabolites. Six dairy lactating Holstein cows with average DIM 26± 3 (n=3
primiparous and n=3 multiparous cows) were randomly assigned to 1 of 3 experimental treatments (different levels of sesame meal) in repeated 3×3
Latin square design. Experimental treatments were control (without sesame meal), 4.33% sesame meal and 8.66% sesame meal (DM basis). The
experimental periods consisted of 21 d with the first 14 days as adaptation and the last 7 days as sampling days. Increasing level of sesame meal in
early lactation rations did not affect dry matter intake, milk yield and composition (fat, protein and lactose), feed utilization efficiency, apparent
digestibility of nutrients and blood metabolites (P  0.05), while milk urea nitrogen decreased with increasing the level of sesame meal (p < 0.05).
Blood urea nitrogen concentrations also tended (P = 0.1) to decrease with increasing levels of sesame oil. In general, the lack of response in feed
intake and milk yield with increasing the levels of sesame meal in early lactation cow's ration showed that sesame meal could be a proper protein
source in early lactation cow's ration.

Abstract In order to determine the optimum number of test-day records for the progeny test program of Holstein bulls, 732,140 milk yield test-day were used. These milk yield test-days, which were related to 73,214 first parity dairy cows belonging to 62 herds, had been collected by the Animal Breeding Center of Iran from 1992 to 2016. The correlation of predicted breeding value (EBV) of bulls from ten test-day of their daughters compared with EBV predicted from different number of recorded test-days. The Correlation of predicted EBV from ten test-days with EBV from even, odd, (second, fifth, seventh), (second, fifth, tenth) and (second, sixth) test-day records were estimated to be 0.99, 0.98, 0.98, 0.97 and 0.94 respectively. The results showed that to reduce cost of recording, number of records and generation interval in EBV prediction of bulls with random regression model it is possible to use only second, fifth and seventh test-days instead of ten test-days.

Abstract The insulin resistance and glucose, insulin, IGF-1 metabolism (somatotropic axis performance) were investigated in cows to receive (4 g yeast/d/head) (Probio-Sacc®, BioChem, GmbH, Germany) or not receive live yeast supplement from 21 d before expected date of calving under the hot months of summer (THI = 82). Two groups of 6 periparturient Holstein cows were fed a diet without or with 4 g yeast/d/head (15*10⁹ CFU/g) starting 21 d prepartum through 8 weeks postpartum to investigate the changes of blood concentrations of glucose, insulin, IGF-1 and glucose tolerance test (GTT). On d 60 postpartum, greater blood levels of glucose, insulin and insulin-like growth factor I were found in cows receiving yeast supplement than those receiving no yeast (P<0/05). Probiotic had not significant effect on GTT test. Overall, it appears that Probiotics would beneficially improve the blood concentrations of glucose, insulin, IGF-1 in day 60 postpartum (on DFS day) and improve somatotropic axis of dairy cows during the heat stress. Probiosac probiotic had positive effects on somatotropic axis and animal performance. It’s can be a good solution to increase dairy cow’s performance in heat stress condition.

Abstract This study examined the effects of partial replacement of soybean meal (SBM) with heat-treated soybean meal (HSBM) in heat-stressed cows. 32 multiparous Holstein cows (DIM = 110 ± 20; milk yield = 40 ± 4.1 kg) were used in a complete block randomized design with a 2×2 factorial arrangment of treatments. Treatments included two dietary crude protein levels (i.e. 17 and 15.5%) each combined with HSBM partially replaced for SBM. The experiment was conducted in two periods of 28 days with the last seven days for sampling and collection of data of tempreature, nutrient intake and digestibility and blood variables. Average THI showed that cows were in mild heat stress (70.60 and 71.50 for periods 1 and 2, respectively)(p > 0.05). Diets with 15.5% CP and based on HSBM increased intakes of dry and organic matter (p < 0.05); however, this was not observed in diets with 17% CP. Milk yiled and composition, apparent nutrient digestibility and blood variables were unaffected (p > 0.05). Butyric and isovaleric acid were increased in cows received HSBM (p < 0.05); however, level of CP had no effect. Results showed that feeding HSBM in diets with 15.5% CP could be regarded as a nutritional sterategy for improving DM intake of mild heat-stressed cows.

Abstract The aim of this study was to compare the efficiency of five synchronization protocols, economically, in Holstein cows during heat stress. This experiment was conducted at a commercial dairy farm in summer 2015 (temperature humidity index 73–81). Five hundred Holstein dairy cows with ˃25 kg/d milk yield were randomly assigned to five experimental groups: 1) ovsynch; 2) presynch-ovsynch; 3) double ovsynch; 4) G7G-ovsynch and 5) PG7G-ovsynch. Results showed that synchronization rate was significantly lower in ovsynch compared to other protocols (P ˂ 0.05). Presynchronization of cows before initiation of ovsynch improved conception rates (CR) at 32 and 62 days (d) after AI compared to ovsynch protocol (P ˂ 0.05). According to the reproductive CR at 32 and 62 d after AI and pregnancy loss, it was found that G7G and PG7G were the best protocols compared to other protocols. The cost associated with the semen use per conception was highest at ovsynch and lowest at both G7G and PG7G protocols. Total costs per conception at 60 d after AI were lowest (1890000 rials) in G7G-ovsynch compared to other protocols. In conclusion, considering total costs associated with hormones and semen use per pregnancy, the G7G protocol is economically the most effective among the studied protocols.

Abstract 15 Holstein cows (1st lactation, 554 ± 57 Kg) randomly divided into three groups. Cows fed Vicia ervilia seed at the rate of 0%, 7% and 14%, DM of dietary, which replaced with Soya been meal and barely. Vicia ervilia (VE) contain approximately: 93.93% DM, 22.8% CP, 5.95% Ash, 3.02% EE, 63% NFE, 5.23% CF, 15.01% NDF and 6.13% ADF. The effective ruminal degradability of CP and DM of VE amounted to 74.76% and 70.57% respectively. Milk production increased in 14% group compared with control (P< 0.05). The values of urea nitrogen in treated cows were significantly increased (P< 0.05). The result of this study indicated that the Vicia ervilia can be used as a protein source replaced with Soya been at the 14% level in dairy cows ration during lactation period after partition.