abdollah kavian

Selecting a breed with appropriate economic performance is one of the most challenging decisions that cattle farmers have to make. The Holstein breed has been imported to the country in the past few decades to increase milk production. This breed is scattered in different climates of Iran, including Golestan province, almost without previous study. Holstein is a breed with high milk production and sensitivity to heat stress. This breed in Golestan province did not have suitable reproductive and economic indicators. On the other hand, dual-purpose breeds, such as Montbéliarde, experience less thermal stress with less feed consumption. Therefore, the research was conducted to evaluate the performance of some reproductive traits and milk production of the Holstein breed, Montbéliarde breed, and hybrids to recommend a suitable breed in the region.

This study was carried out to evaluate the economic characteristics of some reproductive traits and milk production of Holstein cows with Montbéliarde cows and their crossbreeds in Golestan province in northern Iran. In this study, 395 cows were evaluated in the form of a completely randomized design. Indicators such as the age of first insemination and calving, open days, calving interval and the number of inseminations leading to fertility, length of pregnancy period, calf birth weight, and milk production Holstein, Montbéliarde, and 50:50 and 25 crosses: 75 Holstein x Montbéliarde were studied for 5 years in the same geographical point and same management. Meteorological data from 1390 to 1399 was analyzed with the approach of drawing the conditions of livestock breeding environment.

Investigating the results of long-term meteorological data showed that the temperature-humidity index has been above 68 for almost six months, and high-yielding dairy cows in this region are probably experiencing heat stress conditions. Based on the data of this research, Holstein cows showed more open days, so the number of inseminations leading to fertility in this breed increased, and the cost of maintenance, feed, as well as cost artificial insemination, and delay in pregnancy on the farm increased. The calving interval in the Montbéliarde breed, Holstein mixed with 75% Montbéliarde x 25% Holstein, 50% Holstein x 50% Montbéliarde was 398.31, 392.42, 387.59, and 421.72 days, respectively.

Conclusion:

The results of this research showed that the reproduction efficiency of Montbeliarde breeds cows in Golestan province was better than Holstein breed, moreover, heavier calves were produced. It seems that heat stress conditions in the region were more effective in Holstein cows with higher milk production. In an economic evaluation of milk production and herd longevity without considering meat production, the Montbéliarde breed was better than Holstein. It seems that breeding the Montbéliarde breed in the warm and semi-tropical conditions of the north of Golestan province is a more suitable option than the Holstein breed.

All breeds of Irannians sheep except Zel has a fat tail, and despite their lower carcass fat percentage, male lambs have higher fat-tail weight. Using within breed genetic variation requires accurate and precise measuring of fat tail weight on candidates of selection. The aime of this study was comparision of artificial neural network (ANN) modeling and linear modeling methods to prediction of fat tail weight, using body weight and different tail dimensions. 32 lambs of Chal and Zandi breeds,crosses of Zandi×Chal,Zel×Zandi and Zel×Chal hybrids were used for modeling to an estimation of fat-tail weight. Inputs of the model was birth type, sex, breed, upper width , mid width and lower width of fat tail,fat tail height and body weight, output of the model was fat tail weight. body weight, genotype, and fat tail mid-width had the largest positive correlations with fat-tail weight,0.83,-0.82 and0.80,respectively. The adequacy parameters of the best artificial neural network model had a coefficient determination of 0.99 and a mean squared error(RMSE)of 70.3g. The values of these estimated parameters by the multiple linear model were 0.891 and 263.86, respectively. The results of the extension of the original study showed the complexity of the interactions between the model inputs. Present research approved to accurate and unbiased estimation of tail weight of different breeds and crosses using artificial neural network. Furthermore, present study showed that ANN model can be used for accurate and presise estimation of fat tail weight using measured traits on sheep,than linear model.

This study aimed to investigate the nutritive value and in vitro digestibility of the silage from five varieties of sorghum involving (ICRISAT623×R165, ICRISAT632×R165, ICRISAT625×165, ICRISAT520×166 and speed feed) in a completely randomized design with five replicates. The dry matter(DM) and crude protein(CP) yield of the sorghum varieties were determined and then were ensiled in plastic buckets. The difference between sorghum varieties was significant in terms of DM and CP content before ensiling. ICRISAT520 ×R166 had the highest DM and CP yield and Speed Feed cultivar had the lowest yield. The results showed that silage cultivars had a significant difference in chemical composition (P <0.05). ICRISAT625 ×R165 had the highest content of fat, water soluble carbohydrates (WSC), and metabolism energy (ME) and Speed Feed had the highest amount of acid detergent fiber (ADF) and ammonia nitrogen (NH3-N). There was a significant difference between 5 cultivars in estimating of dry matter digestibility (DMD), organic matter digestibility (OMD) and metabolizable energy (ME). DMD and OMD in silage of ICRISAT625×625 (57.71% and 54.17%) and ICRISAT625×623 (56.30% and 55.04%) were higher than the rest of the cultivars. The highest ME was observed in ICRISAT625×165(7/8 MJ/Kg) and ICRISAT623 ×R165 (7/6 MJ/Kg). Generally, in terms of fresh consumption ICRISAT520×166 is recommended for cultivating in Golestan province due to higher DM and CP production than other cultivars (18487 and 1400 kg ha-1 respectively), but ICRISAT625 × R165 variety of sorghum silage is superior to other cultivars in terms of ME.