Full text
| |
| Author(s): |
Mariana Pompêo de Camargo Gallo
Total Authors: 1
|
| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2013-04-22 |
| Examining board members: |
Carla Maris Machado Bittar;
João Alberto Negrao;
Ivanete Susin
|
| Advisor: | Carla Maris Machado Bittar |
| Abstract | |
The study evaluated the effect of the level of concentrate intake at the 5th week of age and the weaning method on the performance, metabolism and physiology of dairy calves. In a 2x2 factorial design, using 36 dairy calves, animals were classified as presenting high (>350g/d) or low (<350 g/d) concentrate intake at the 5th week of life, and distributed in two weaning methods: abrupt or gradual. Animals were individually housed in hutches, had free access to water and concentrate (up to 2kg/d) and were fed 4L of milk-replacer. The abrupt weaning was done at the 8th week of age. Animals weaned gradually received milk-replacer at the rate of 4l/d until the 6th week of age, 3L/d from the 6th until the 7th week, 2L/d from the 7th until 2 days before weaning, and 1L/d until weaning at the 8th week of age. Concentrate intake was monitored daily. Animals were weighted and corporal measures, as well as, blood samples were taken weekly for glucose, ?-hydroxybutyrate (BHBA) and serum total protein (TP), until the 10th week of age when the experimental period ended. Animal behavior was monitored on days -14, -7, -2, 0, 2, 7 relative to weaning. On those days blood samples were drawn for cortisol and acid soluble glycoprotein (ASG) levels determination. There was no significant interaction of the studied factors for all the analyzed variables. Average concentrate intake was not affected by the weaning method (P>0.05), however there was an significant age effect (P<0.001) according to the level of intake at the 5th week of age. Animals at the high intake level group presented higher hay intake at the 9th week of age (P<0.05). Weaning method had no effect on: live weight, daily gain or corporal measures (P>0.05); however, there was a significant difference for those variables according to the level of intake (P<0.05). There was no significant interaction of the intake level at the 5th week and the weaning method for blood parameters. BHBA concentrations were higher for animals at the higher concentrate intake level for almost the whole period. Cortisol and TP were not affected by the studied factors or by the animals age (P>0.05). Weaning methods had no effect on physiological measures. Concentrate intake level affected (P<0.05) heart rate at 6:00, 12:00, 18:00; and rectal temperature at 18:00. Animals gradually weaned spent more time consuming concentrate (P<0.05); and time ruminating and consuming concentrate were increased as animals aged (P<0.05). The number of vocalizations were higher (P<0.05) at the weaning day and the second day after that, getting back to normal a week after. The weaning method affected the number of vocalizations at the second day after weaning (P<0.05), with animals weaned gradually presenting lower numbers. The weaning method had no effect on performance, metabolism or well-being of dairy calves. However, the intake level had impact on performance and blood parameters. In spite of performance, metabolism and stress level of the animals the concentrate intake level is more important than the method of weaning. (AU) | |
| FAPESP's process: | 11/01349-1 - Metabolic and behavioral changes in calves as a function of stress in response to gradual or abrupt weaning |
| Grantee: | Mariana Pompeo de Camargo Gallo |
| Support Opportunities: | Scholarships in Brazil - Master |