Effects of bovine somatotropin and evaporative cooling plus shade on lactation performance of cows during summer heat stress
| Autor: | C. Nussio, José E. P. Santos, M.A. Tarazon-Herrera, L. Nusso, J.T. Huber, H. Mena |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
medicine.medical_specialty
Hot Temperature media_common.quotation_subject Randomized block design Fatty Acids Nonesterified Body Temperature Animal science Blood serum Internal medicine Lactation Genetics medicine Animals Dry matter Bovine somatotropin Dairy cattle media_common Heat index Chemistry food and beverages Appetite Humidity Environment Controlled Endocrinology medicine.anatomical_structure Growth Hormone Animal Science and Zoology Cattle Female Seasons Food Science |
| Zdroj: | ResearcherID |
| ISSN: | 0022-0302 |
| Popis: | Thirty-two Holstein cows (8 per treatment) averaging 195 d in milk were assigned to 70 d of treatment on the basis of production during a 14-d pretreatment period, which was used for covariate analysis. The experiment was a randomized block design with a 2 × 2 factorial arrangement of treatments. Factors were normal shade or shade plus evaporative cooling with pressurized spray, plus with or without the administration of bovine somatotropin (bST). Cows receiving bST were injected with 500 mg of bST every 14 d. All cows were fed the same total mixed rations twice daily at approximately 10% in excess of appetite, and water was offered free choice. There were no interactions between bST and the cooling system for any of the variables measured. Milk yield was increased by bST and tended to be greater for cooled cows. Fat percentages were increased by bST, and yields of fat, protein, and 3.5% fat-corrected milk, and the efficiency of conversion of dry matter to milk, whereas evaporative cooling increased body weights and protein yields, but decreased SNF and milk protein percentages. Rectal temperatures and respiration rates also were lower for cooled cows. And, bST increased nonesterified fatty acids in blood serum, suggesting that a part of the energy for increased milk production came from mobilization of body fat. Administration of bST effectively improved performance of cows under hot summer conditions whether evaporatively cooled or not. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|