| The thesis aimed to explore the effects of body condition on the delivery behavior,plasma hormone contents,calves' birth weight,colostrum intake and the effects of cow's licking on calves' behavior and serum parameters,in order to provide a scientific basis for the better management of cows and newborn calves.This paper consists of two experiments,the contents are as follows:Experiment 1: This experiment was conducted to study the differences of calving behavior and plasma hormone contents in cows with different body condition,and to explore the influence of body condition on the birth weight and colostrum intake of new born calves.Thirty-six healthy Holstein cows were selected and divided into high body condition score(BCS)group(3.75?BCS?4.25,20 cows)and moderate BCS group(3.25?BCS?3.50,16 cows).The calving behavior was recorded by video recording.The plasma hormone contents of cows after delivery were measured.The birth weight and the colostrum intake of calves were recorded.The results are as follows: 1)the time from the onset of rhythmical abdominal contractions to the birth of the calf of the high BCS cows was significantly longer than that of the moderate BCS cows(P<0.05).The time from a visible amniotic sac to the birth of the calf of high BCS cows tended to be longer than that of the moderate BCS cows(P=0.09).The times of posture change from standing to lying of the high BCS cows tended to be more than that of the moderate BCS cows(P=0.08).2)The plasma prolactin content of the high BCS cows was significantly lower than that of the moderate BCS cows(P<0.05),the plasma oxytocin content of tended to be lower than that of the moderate BCS cows(P=0.06),whereas the plasma cortisol content was significantly higher than that of the moderate BCS cows(P<0.05).3)The percentage of calves ingested 6 L total colostrum intake from high BCS cows tended to be lower than that from the moderate BCS cows(P=0.09).It is concluded that the high BCS cows had a higher stress response and a longer calving process compared with the moderate BCS cows,and their calves' colostrum intake was lower.Therefore,we should pay attention to the body condition management of perinatal cows to avoid obese body condition.Experiment 2: The experiment was conducted to study the effects of cow's licking on the behavior,stress level and immunity of newborn calves.Thirty healthy Holstein female calves with similar birth weight were selected and divided into two groups according to the durations of the calves were licked by the cows after birth.The calves were licked only a few times or not being licked were considered as the control group(Con group,15 calves).The calves were licked for 15~20 minutes after birth were classified as the group been licked(Lick group,15 calves).The behavior of calves during the 24 hours after being licked was recorded by video recording,and the serum stress hormone and immune cytokines at 0 and 24 hours after being licked were measured.The results are as follows: 1)The time interval from entering the calf house to the first successful standing of the Lick group tended to be shorter than that of the Con group(P=0.06).The standing attempt times between the first standing attempt to the first successful standing tended to be less for the Lick group calves compared with the Con group calves(P=0.09).The time from the first standing attempt to the first successful standing of the Lick group was significantly shorter than that of the Con group(P<0.05).2)The proportion of standing duration to total duration of colostrum intake of the Lick group was higher than that of the Con group.(P=0.07).3)Arounding the time of colostrum intake,the standing duration and standing bouts of the calves from the Lick group were significantly longer and more,respectively,than those from the Con group(P<0.05,P<0.01);the lying duration of the Lick group was significantly shorter than that of the Con group(P<0.05);the walking duration and walking bouts of the Lick group were significantly longer and more,respectively,than those of the Con group(P<0.01,P<0.01);the exploring duration of the Lick group tended to be longer than that of the Con group(P=0.08),and the exploring bouts of the Lick group was significantly more than that of the Con group(P<0.05).4)The serum cortisol level of the Lick group was significantly lower than that of the Con group(P<0.05).At 24 hours after birth,the serum level of IL-2 of the Lick group tended to be lower than that of the Con group(P=0.097).The IL-6 level of the Lick group was significantly lower than that of the Con group(P<0.05).In conclusion,calves being licked by their dams for 15~20 minutes after delivery can reduce their stress level,enhance their vitality,and being more active. |
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