Banca de QUALIFICAÇÃO: POLIANA RAMOS DA SILVA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : POLIANA RAMOS DA SILVA
DATE: 01/06/2022
TIME: 09:30
LOCAL: Sala virtual
TITLE:

Temperament, physiological parameters, and performance of Nelore calves submitted to different weaning methods

KEY WORDS:

Psychological stress. Godmother cows. Fence line. Reactivity.

PAGES: 40
BIG AREA: Ciências Agrárias
AREA: Zootecnia
SUBÁREA: Produção Animal
SPECIALTY: Manejo de Animais
SUMMARY:

The present study was carried out to investigate different weaning methods on physiological responses (heart rate - HR, respiratory rate - RR, rectal temperature - TR and cortisol levels) and performance (body weight, average daily gain - ADG, and body condition score - BCS) of Nelore calves under grazing. Additionally, the animals were classified as calm and reactive to define the effects of temperament on physiological parameters and post-weaning performance. 183 purebred Nelore males and females, weaned at 8 ± 1 months, were randomly assigned to three different weaning methods: 1) Abrupt (AB) – total separation between cow and calf; 2) Fenceline (LC) – physical separation between cow and calf by means of a fence; and 3) Godmothers (MA) – use of unrelated and non-lactating cows as social leaders. After the 7th day after weaning, the calves were grouped in a single paddock. Physiological measurements and blood samples for cortisol analysis were performed on days 0, 1, 4, and 7. Temperament at 0, 7, and 82. And the performance at 0, 42, and 82 days post-weaning. The results showed a greater number of animals classified as calm from weaning today 82 (P<0.05). There was interaction (P<0.05) between weaning methods and calves' temperament for TR at 7 days post-weaning. HR, RR, and TR were not different (P>0.05) 1 day after weaning. However, there is (P<0.05) higher HR in MA and higher TR in LC on the 4th day. As well as higher (P<0.05) TR in AB and MA methods at 7 days post-weaning. Cortisol levels were not different (P>0.05) when submitted to weaning or temperament methods. From weaning to the 42nd day after weaning, MA and LC calves received the highest body weight and ADG (P<0.05), while AB had the lowest weight and negative ADG (-0.032 kg/day). After this period, the different methods did not influence the performance (P>0.05). Regarding temperament, calm animals received (P<0.05) higher body weight and ADG from weaning up to 82 days after weaning. Thus, physiological parameters do not clearly indicate the best weaning method, probably due to the influence of environmental temperature. Performance results directly us to methods that provide less psychological stress, such as fence lines or godmothers. However, due to the more laborious handling of separation by a fence, the method that uses godmother cows as social leaders can be considered the least stressful, in addition to being easy to perform. Furthermore, performance can be influenced by temperament, especially when intense handling is reduced.

BANKING MEMBERS:
Interna - 1839209 - DAIANY IRIS GOMES
Externo ao Programa - 1632663 - LUIS RENNAN SAMPAIO OLIVEIRA
Externa à Instituição - LÍVIA VIEIRA DE BARROS - UFMG
Externa à Instituição - FRANCIELY DE OLIVEIRA COSTA
Externa à Instituição - MONIQUE VALERIA DE LIMA CARVALHAL