RESUMO
Vulnerable animals to heat stress have been described as ones with dark or black hides due to increasing absorption of solar radiation. The effect of coat color in pluriparous contemporary Holstein cows in a hot environment (mean annual temperature 24.6⯰C), on body surface temperature (infrared thermography), physiological and hematological variables as well as milk yield and reproductive performance was assessed using 178 Holstein pluriparous cows (74 predominantly white and 104 predominantly black). Data were collected in the morning and afternoon in July (mean temperature-humidity index 82 units). Body condition score at mid-lactation (128⯱â¯32 days in milk at the start of the experiment) was higher (Pâ¯<â¯0.01) in predominantly white than in black cows (3.3 vs. 3.2). Respiration rate did not differ between groups (72⯱â¯23 vs. 73⯱â¯20 breaths/min for white and black cows, respectively, sampling time combined). In contrast, rectal temperature of black cows was 0.1⯰C higher (Pâ¯≤â¯0.01) than white cows, regardless of sampling time. The only significant hematologic change was a slight increase in mean corpuscular volume in black cows (54.7â¯fL, Pâ¯<â¯0.01) compared to white cows (53.8â¯fL), but it remained within the reference range. Differences due to coat color did not alter body surface temperatures at any time of the day. Conception rates, services per conception, calving intervals and fetal losses were not associated with hair coat color, but cows with predominantly white coat produced 394â¯kg more (Pâ¯<â¯0.01) fat-corrected milk in 305 days compared to cows with predominantly black coat. It was concluded that in this hot-arid environment with cows housed in facilities with extensive cooling, black hair coat moderately reduces 305-d milk yield without affecting milk composition, body surface temperature, and reproductive performance.
Assuntos
Temperatura Corporal , Bovinos/fisiologia , Cor de Cabelo/fisiologia , Resposta ao Choque Térmico , Leite/metabolismo , Reprodução , Animais , Feminino , Fertilização , Temperatura Alta , Lactação , Leite/química , Paridade , GravidezRESUMO
Purpose of this study was to develop an early warning system for heat stress in cattle. For this purpose, total of 8 lactating cattle (4 Holstein of which 2 high and 2 low producing, 4 Brown Swiss of which 2 high and 2 low producing) which were raised at Dalaman branch of Agricultural Enterprises Directorate of Turkey were used. Before starting the experiment, adjustment time was given to the cattle to get used to human presence. After animals were accustomed to the human presence, researcher positioned herself in a shaded area where cattle came for shade seeking and skin temperature of cattle was read by infrared thermometer and also rectal temperature was read by using rectal probe. Temperature readings were taken at 10:00, 13:00 and 16:00. Study started on July 16 and lasted until August 16 when most of the heat stress is observed. Panting score of the animals were also recorded. Results showed that panting score increased as skin surface temperature increased. Rectal temperature also increased with panting score. Holstein cattle tended to have higher panting score than Brown Swiss cattle. Results showed that measuring skin surface temperature of cattle by infrared thermometer and observing panting scores could be used to early warn heat stress in cattle.
Assuntos
Animais , Bovinos , Temperatura Alta , Temperatura Corporal , TermômetrosRESUMO
Purpose of this study was to develop an early warning system for heat stress in cattle. For this purpose, total of 8 lactating cattle (4 Holstein of which 2 high and 2 low producing, 4 Brown Swiss of which 2 high and 2 low producing) which were raised at Dalaman branch of Agricultural Enterprises Directorate of Turkey were used. Before starting the experiment, adjustment time was given to the cattle to get used to human presence. After animals were accustomed to the human presence, researcher positioned herself in a shaded area where cattle came for shade seeking and skin temperature of cattle was read by infrared thermometer and also rectal temperature was read by using rectal probe. Temperature readings were taken at 10:00, 13:00 and 16:00. Study started on July 16 and lasted until August 16 when most of the heat stress is observed. Panting score of the animals were also recorded. Results showed that panting score increased as skin surface temperature increased. Rectal temperature also increased with panting score. Holstein cattle tended to have higher panting score than Brown Swiss cattle. Results showed that measuring skin surface temperature of cattle by infrared thermometer and observing panting scores could be used to early warn heat stress in cattle.(AU)