Study On Heat Tolerance Of Jersey, Holstein And Jersey X Holstein Dairy Cows

Heat stress seriously affects the production performance of animals, causing huge economic losses to the cultivation industry. At home and abroad there are more research report of Holstein cows heat stress,but less Holstein cattle, Jersey cattle and Jersey X Holstein cattle, three Bovine heat resistance.This research systematicaly on Holstein, Jersey cow and Jersey X Holstein cattle production performance and body physiological and biochemical indexes heat stress of the situation, designed to study heat stress, heat resistance performance of different varieties of cows, which provide a theoretical basis for the screening of the dairy cattle breeding varieties suitable for the hot and humid climate.Test uses the Pilot varieties packet design, according to the cows groups healthy non-disease, similar parities times (1to2fetus),30-185days in milk for postpartum, groups in milk lactation days, the principle of yield milk similarity for one week before the experiment of the test,cattle are divided into three groups:Holstein cows group, Jersey cow sGroup, Jersey X Holstein dairy group, each test dairy cows quantity is15,and by the THI changes situation during the test duration, controlled trials of mild heat stress, moderate heat stress and heat stress period. The results showed that:1. The pre-experimental period statistical results display,under the premise of no clear diversity in parity (P>0.05), lactation days was significantly lower than (P<0.05) Holstein and Jersey X Holstein cattle, Jersey cow lactation days milk production was apparently lower than Holstein and Jersey X Holstein cattle (P<0.05).2. Heat stress period barn THI in average was greater than72, the heat stress response occurrenced in cows. The average temperature of the entire thermal stress test period in barn was33.37"Cand humidity was25.36%, and THI value in average was82.65, visiblely higher than the non-thermal stress period THI57.24(P<0.05).3. Physiological contant:heat stress in dairy cattle rectal temperature and respiratory rate were distinctly higher than those of non-thermal stress index (P<0.05). Average rectal temperature of the whole heat stress period in Holstein cattle was39.51℃, compared with non-heat stress increased by 2.38%; Jerseys average is39.20℃, raised1.84%; Jersey X Holstein cattle average was39.43℃, increasing2.33%. Average respiratory rate of the whole heat stress period Holstein is80.90beats/min, as an increase of58.94%, the whole heat stress Jerseys average number of breaths was71.90/min,growing up59.83%than non-thermal, the entire heat stress Juan miscellaneous cattle average respiratory rate of82.08beats/min, mounting60.94%. Indicators of statistical results from the physiological point of view, the best is Jerseys heat resistance, followed by Jersey X Holstein cattle. Finally, there is the Holstein.4. Feed intake:from the period of heat stress to non-heat stress in Holstein cows dry matter intake raised36.47%; Jersey cow grew up30.45%; Jersey X Holstein cattle went up31.86%. Whether it is in the period of heat stress or non-heat stress, Holstein cattle and Jersey X Holstein cattle feed intake are significantly higher than the Jersey cattle (P<0.05). Holstein trial period intake are fluctuating, and Jersey X Holstein cattle feed intake changes between Jerseys and Holsteins.5. Performance included milk yield and milk composition:from non-thermal stress to heat stress, Holstein milk production decreased by26.36%; Jersey cattle dropped14.08%; Jersey X Holstein cattle fell down23.49%. The performance of Jersey X Holstein cattle milk fat, milk protein and milk solids content was always between Jerseys and Holsteins, slightly better than the Holstein cattle. Jersey cattle the hybrid cattle feed utilization was higher than Jerseys and Holsteins.6. Reproductive performance:in general frozen and annual average conception rate Jersey cattle had optimal performance, followed by Jersey X Holstein cattle, and finally Holstein. The days of pregnancy of Jersey cattle and Juan miscellaneous cattle was evidently lower than Holsteins (P <0.05). The records of Holstein group production was apparently higher than the Jerseys and Jersey X Holstein cattle (P<0.05).7. serum biochemical indicators:from heat stress to the non-thermal stress of cow serum TC, TP, Alb and HSP70content is decreasing, while T3, T4and SOD content is rising. In the heat stress of the Jersey and Jersey X Holstein cattle TC, Alb, SOD and HSP70is markedly higher than the Holstein’s (P<0.05); Holstein and Jersey X Holstein cattle TP’s content was distinctly more than the Jerseys; Jerseys T3, T4content was clearly greater than Holstein and Jersey X Holstein cattle (P <0.05); Holstein T3, T4content was expressly more quantity than Jersey X Holstein cattle (P<0.05). Non-thermal stress of Holstein cattle the content of TC, SOD, Alb and HSP70in serum are significantly lower than Jerseys and J Jersey X Holstein cattle (P<0.05); Holstein dairy cow serum TP content was broadly higher than Jerseys and Jersey X Holstein cattle (P<0.05). The three groups cow T3content difference is not clear(P>0.05); Holstein and Jersey cattle content for T4was significantly more plenty of than Jersey X Holstein cattle (P<0.05).In summary,in heat stress, period cows rectal temperature, respiratory rate increased clearly, the test milk production, milk quality and feed intake decreased in varying extent, and cows serum TC, T3, T4, SOD water on average significantly low down in different degrees, TP, Alb and HSP70levels were visibly raised. During the comprehensive three groups of cattle heat stress and non-heat stress, Jersey X Holstein cattle can be regarded as better heat resistance varieties to be nurtured and generalization.