The study objective was to evaluate the effects of reducing dietary starch content in fresh cow diets while maintaining NDF levels by substituting barley grain (BG), corn silage (CS), or both with beet pulp (BP) on DMI, lactation performance, serum mineral and metabolites concentrations, liver enzymes and liver functionality index (LFI), serum insulin and revised quantitative insulin sensitivity check index (RQUICKI). Thirty-six multiparous cows were randomly assigned to 1 of 4 experimental diets from calving to 21 days in lactation. Experimental diets were a high-starch diet with ground BG (CO; 24.9% starch; 0% BP) and 3 low-starch diets where BP substituted for either BG (BB; 19.6% starch; 7% BP), CS (BC; 20.6% starch; 12% BP) or CS and BG (BCB; 20.3% starch; 12% BP). Relative to CO cows (16.50 kg/d), DMI was greater for BC (17.70 kg/d) and BCB (17.50 kg/d) cows, but it was lesser in BB (15.60 kg/d) cows. Similar to DMI results, milk yields tended to be greater for BC (37.89 kg/d) and BCB cows (37.81 kg/d) compared to CO cows (35.41 kg/d), but BB cows (33.05 kg/d) tended to produce less milk than CO cows. Relative to CO, cows fed BB had lower serum glucose concentrations, whereas cows fed BC and BCB had higher serum glucose. Serum insulin concentrations were lower for BB cows than for other exprimental groups. Relative to CO, serum NEFA and BHB concentrations were lower for BC and BCB, but was similar between BB and CO. The RQUICKI was lower for CO, BC cows than BB cows, and cows in BCB tended to have less RQUICKI compared to BB during postpartum. The concentrations of gamma glutamyl transferase were lower in BC and BCB cows relative to CO and BB cows. The cows fed CO and BB had higher serum bilirubin relative to cows fed BC and BCB diets. Although, LFI for CO cows was similar to cows on BB, BC and BCB, BC cows had higher LFI than BB cows and tended to have greater LFI than CO cows. Overall, reducing dietary starch by replacing CS (BC) or a mix of CS and BG (BCB) with BP positively affected DMI and milk yield and indicated improved energy metabolism and liver function during the first 21 d of lactation compared to when BP was fed instead of BG to reduce starch (BB).

The objective of this study was to evaluate the effect of supplementing close-up diets with rumen undegradable protein on serum metabolites and the incidence of health disorders of Holstein dairy cows, during the hot season. Eighty-eight multiparous Holstein dairy cows were randomly assigned to 1 of 2 treatment groups: low crude protein (14.3% CP; 14CP) and high crude protein (17.1% CP; 17CP) diets. Blood samples were collected weekly from d -30 up to calving and then at 0, 5, 14, and 21 days after calving, for serum metabolites determination.  Cows fed the 17CP diet had higher serum concentrations of albumin, blood urea nitogen, and Mg than 14CP cows during the close-up period. In postpartum, the 17CP cows had higher serum albumin and creatinine and lower free fatty acid, BHB, and glucose concentrations than the 14CP cows. The risk to developing subclinical ketosis (SCK), metritis and endometritis were higher for the 14CP cows than the 17CP cows. Overall, feeding high rumen undegradable protein diet to close-up cows during the hot season increased serum creatinine concentrations and lowered the incidence of SCK and metritis and endometritis postpartum.

Introduction: Secondary sex ratio (SSR) is the proportion of males to females at birth. It has been shown in many different mammalian species, many factors are associated with SSR. Changes in secondary sex ratio in dairy cows is considered economically important and the ability to change it could affect the revenues and profitability of a dairy farm. Thus, sperm or embryo sexing techniques in recent years has attracted more attention. Most breed of dairy cattle are more likely to have female calf is born to use them as replacement heifers and in order to maintain their productive herd number. On the contrary, when the goal is the production of meat, bull calves due to higher growth rates and production efficiency, are more convenient and more economically efficient. The aim of present study was to investigate some key factors affecting SSR in Iranian Holstein cows.According to Fisher, the sex ratio in the population under the control of natural selection is not always the same. There is overwhelming evidence to support the theory that shows Fisher Primary and secondary sex ratio sex ratio can deviate from this balance and natural selection caused a change in this ratio can be in certain circumstances. For example, the secondary sex ratio of 52: 48 has been reported in dairy cows. Studies on mammalian species suggest that several factors, including latitude of the location, the dominant regional climate model, time and frequency of mating to ovulation, diet, age of parents, physical score, breed and produced eggs from ovarian left or right can have a significant effect on the secondary sex ratio. Weather conditions may modify the internal environment and the effect on physiological mechanisms or through the impact on the frequency and type of foods available to parents, the secondary sex ratio is impressive. The impact on the quantity and quality of parent's access to food sources in many species of mammals, the sex ratio has been fixed.Previous reports have shown that high environmental temperature and higher rates of evaporation from a week to a month before conception secondary sex ratio was increased.Materials and method: The demographic, production and reproduction data of six large dairy farms between years 1375 and 1389 were used. The rolling average of 305 d fat corrected milk yield was 8145 kg with a range of 7578 to 8670 Kg. Breeding Center of Iran and the herds covered by the registration and recording them on a regular basis carried out by experts dairy cooperatives. The flocks were in the area northeast of the country.Production data (date corrected milk production and the cumulative production by 60 and 305 days of lactation), reproductive data (such as calving year, calving season, type of birth, sex of calf, the latest information on AI, days open), and details the possible removal of the flock or death were recorded. Data were collected from flocks before the analysis was re-verification. Used by sperm, sperm into four groups: Iranian, Canadian, American and other countries (including sperm taken from European countries) groups. The data were analyzed using multivariate logistic regression model.Statistics 0/05 was used to ensure meaningful results.Results and discussion: Results showed that the ratio of males to females was 53 to 47. Origin of the sires (including Iranian, American, or Canadian) had no impact on secondary sex ratio. Type of calving (eutocia vs.non-eutocia calving including dystocia and still birth) had significant impact on SSR (P<0.05). SSR was not effected by calving year. Season of calving, days open, parity, and the corrected 305 d milk yield also had no impact on SSR while the interaction of parity and type of calving was significant (P<0.05).Conclusion: In conclusion, the results of this study shows that type of calving only had a significant effect of SSR.

BACKGROUND: Postpartum anestrus is a major problem in primiparous dairy cows.OBJECTIVES: The objective of this study was to investigate postpartum ovarian activity in primiparous Holstein dairy cows.METHODS: Seven primiparous Holstein dairy cows were monitored for ovarian activity using a combination of ultrasound examination and alteration in progesterone concentrations. Daily blood sampling and ultrasound examination were conducted starting from day 6 until the third ovulation postpartum.RESULTS: First wave dominant follicles (³10 mm in diameter) were detected on day 11.5±1.48 postpartum. This follicle did not ovulate in any of the experimental cows. Moreover, none of the cows ovulated within 20 days postpartum. There was no difference in the follicular growth rate and the diameter of ovulatory follicles between the first, the second and the third ovulations postpartum (p>0.05). Interval from calving to the first postpartum ovulation was 48.1±6.89 days. Mean diameter of corpus luteum and progesterone concentrations of the first cycle (18.8±0.94 mm and 2.0±0.24 ng/mL) were significantly less than those of the second cycle (24.0±0.89 mm and 3.6±0.36 ng/mL; p<0.05).CONCLUSIONS: In conclusion, increased interval from parturition to the first ovulation is not due to the delayed or lack of the first wave dominant follicle formation after parturition; but is due to the regression of this follicle.

The aim of this study was to evaluate the factors affecting days open (DO) as the main reproductive performance and longevity index in Holstein dairy cows in Iran. The demographic, production and reproduction data of six large dairy farms were used. The data were analyzed using Standard Least Squares models. Survival analysis using Kaplan-Meier method was used to determine the impact of DO on longevity. The results showed that DO and dystocia were increased during the recent years (P<0.01). Days open was increased due to the higher milk yield in recent years (P<0.01). Non-eutocia calving also increased the DO (P<0.01). Parity impacted DO and cows in their 6th or more lactations had the highest DO (P<0.01). Male calves increased DO (P<0.05). Sire origin had significant impact on DO and Iranian sires had the lowest DO compare to their counterparts (P<0.01). Season of calving had significant influence on DO and cows calved in winter had higher DO compare with their counterparts calved during summer (P<0.01). Increase in DO during the first calving had a negative impact on cow longevity and cows with more than 160 days of DO were culled sooner (P<0.05). In conclusion, the results of the present study demonstrate that DO as the main reproductive performance index is impacted by genetic and environmental factors.

This study was performed to investigate the incidence of abortion based on different definitions and, the effect of climate and herd size on abortion as well as its phenotypic trend. Using calving records collected from 16 dairy herds from years 2004 through 2014. Incidence rate and analysis of affecting factors on abortion were done using the FREQ and GENMOD procedures of SAS software, respectively. According to the definition of abortion as death and expulsion of fetus between 60-260 d, 100-260 d or 150-260 d of pregnancy, overall abortion incidence was 15. 5%, 11. 25% and 6. 6%, respectively. Herd size, climate, parity, year and season of calving as well as the interaction of calving year × season and climate × calving year were associated with abortion (P < 0. 001). Greatest abortion incidence was observed for second parity cows (28. 7%). The highest and lowest rates of abortion (16. 0 vs. 14. 5%) happened in the mild and cold climate, respectively. Also, the larger herds, with more than 3000 cows, had almost 1% higher abortion incidence than smaller herds, with less than 1000 cows. The average rate of abortion incidence was highest in the spring and lowest in the autumn (17. 8 vs. 13. 5 %). According to the regression of least squares means on calving year, abortion incidence showed a positive and significant trend (P < 0. 003) by 0. 4 per year. The results of this study can be used in the analysis of management practices to control abortion.

Background and objectives: Recently the European Simental and Montbeliard dual-purpose breeds have been imported into Iran. Crossbred lactating cows were hypothesized to outperform Holsteins under environmental stresses. The objective of this study was, therefore, to compare production, reproduction, metabolism, and health of purebred Holstein cows vs. crossbred Holstein × Montbeliarde and Holstein×Simmental cows under hot and humid conditions of the north of Iran (Sari, Mazandaran). Material and methods: Dairy crosses were produced by crossing Holstein (H) cows with Montbeliarde (M) and Simmental (S) bulls’ semen. The performance and health of 70 primiparous cows from each breed (210 cows in total) were compared during their first lactation. Blood samples were taken from 15 primiparous cows from each breed at stages of close-up, calving, and 21 days after calving. Samples were analyzed for glucose, BHBA, NEFA, calcium and, magnesium. Statistical analyses were performed using SAS programs (GLM and MIXED procedures). Results: Results showed that Montbeliarde×Holstein and Simmental×Holstein crossbred cows were not different (P> 0. 05) from pure Holsteins in rectal temperature, fertility, and other reproductive indices, 305-d milk yield, milk fat and protein yield, stillbirth, mastitis, and laminitis rates, and close-up blood metabolites. However, Montbeliarde×Holstein cows had greater calving difficulty than did Simmental×Holstein cows (P < 0. 05). Moreover, both crossbred groups had a higher incidence of metritis compared to purebred Holstein cows (P < 0. 05). The purebred Holsteins exhibited more desirable udder traits than did crossbred cows (P < 0. 05). The crossbred cows had a higher body condition score (BCS) during the transition period than did the pure Holsteins (P<0. 05). However, the stature of Simmental×Holstein crossbred cows was shorter than pure Holstein. Foot angle was steeper for Holstein×Simmental and Holstein×Montbeliarde crossbred cows, but Holstein×Montbeliarde crossbred cows were similar to pure Holstein cows for hoof measurements. Conclusions: The findings of this study suggest that Holstein×Simmental and Holstein×Montbeliarde crossbred cows did not outperform the first-lactation of purebred Holstein cows. In adition, the crossbred cows experienced higher rates of dystocia and metritis under stressful hot and humid conditions.

Diuretics have several therapeutic advantages in dairy cows but there are different side effects such as acid-base and electrolyte imbalances which may affect the electrocardiographic parameters. Fifteen multiparous, clinically healthy, non-pregnant and high producing 4-year-old Holstein dairy cows at their early lactation period were randomly divided into 3 equal experimental groups. Furosemide was infused intravenously at 3 different doses containing group 1: 2.5 mg/kg; group2: 5 mg/kg and group 3: 10 mg/kg. Electrocardiogram recordings and blood samplings were performed at prior and 1, 2, 3, 4, 5 and 24 hours after furosemide administrations. Sera after separation were assayed for sodium, potassium, chloride, calcium, magnesium and phosphorus concentrations. There were no significant changing patterns in P, R, S and T amplitudes. P-R, R-R, Q-T and S-T intervals increased significantly after furosemide administrations in groups 2 and 3. Electrocardiographic intervals in groups 3 were higher than other groups (P<0.05). The values of P, R, S and T durations in group 3 increased significantly after furosemide administration. Durations of these waves in group 3 were higher than groups 1 and 2, significantly (P<0.05). There were no significant changing patterns in serum calcium, magnesium and phosphorus levels. Serum concentrations of sodium, potassium and chloride significantly decreased after furosemide administrations in all experimental groups. Levels of these electrolytes in group 3 were significantly lower than other groups (P<0.05). It may be stated that furosemide affects the electrocardiographic parameters by misbalancing the serum electrolytes which affect the electrical conduction of action potential in the myocardium.

Abortion is an important trait with noticeable impacts on economic profit of dairy herds. This study was conducted to estimate variance components and genetic, environmental and phenotypic trends for abortions in Iranian Holstein Friesian cows. The data used were 247230 calving and abortion records of 84421 Hol-stein cows, collected during years 1991-2016, from 51 herds in Iran. Variance components and genetic pa-rameters were estimated using a logit link function, fitting an animal mixed model by ASReml software. In this model, parity and milk yield were fixed, while direct additive genetic, herd-year-season and permanent environment effects were considered as random factors. Genetic, phenotypic and environmental trends were estimated as weighted regression coefficients of breeding values, phenotypic values and environmental deviations averages on birth year, respectively and the number of observations was considered as the weighting factor. Generally, abortion risk in the first parity was lower than the later parities and in autumn was lower than the other seasons. Abortion risk also increased by increase in milk yield level. Heritability and repeatability estimates for abortion were both 0. 165 ± 0. 010. A significant positive genetic trend (0. 038 rate/year) and a significant negative environmental trend (-0. 033 rate/year) were estimated for abortion, which indicated significant increase of genetic predisposition to abortions and improvement of environ-mental conditions to prevent abortion incidence. A significant positive phenotypic trend (0. 002 rate/year) was also estimated, which showed overall increase of abortion rate during the studied years. Overall, it could be concluded that genetic predisposition to abortion is increasing in Iranian Holstein cows, but inclusion of abortion risk in bull proofs and selection indices may help to reduce abortion incidence and increase economic profit of dairy cattle industry.