Banca de DEFESA: IVAN ALBERTO PALHETA SANTOS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : IVAN ALBERTO PALHETA SANTOS
DATA : 06/04/2021
HORA: 14:00
LOCAL: Embrapa Porto Velho
TÍTULO:

Nutritional and heat stress on metabolism, ingestive behaviour and ovarian response in crossbred dairy cows raised in the Amazon Biome

PALAVRAS-CHAVES:

Ketones. Ovulation. Heat Stress.

PÁGINAS: 65
GRANDE ÁREA: Ciências Agrárias
ÁREA: Zootecnia
RESUMO:

The present work aims to evaluate the physiological responses of reproductive interest resulting from thermal and nutritional stress. The experiment was carried out at the research unit of EMBRAPA Rondônia, in Porto Velho. Twelve lactating Girolando cows (± 60 days postpartum) were used, in a random stage of the estrous cycle. The treatments were: I - Rainy season + supplementation; II - Rainy season without supplementation; III - Dry season with supplementation and; IV - Dry season without supplementation. The cows were submitted to the protocol in a 2x2 crossover design, so that all cows receive the four treatments. The animals were placed in an intermittent stocking system. Weekly blood samples were taken from the animals to evaluate cortisol, T3 and T4, the concentration of ketone bodies was measured by Ketovet®. The evaluation of voluntary consumption was made through LIPE®, and the evaluation of thermal comfort was made through a black globe, to measure the globe temperature and humidity index, in addition to an intravaginal data logger with evaluations for each one hour, follicular dynamics was assessed by ultrasound. All statistical analyzes were performed using the SAS statistical program (1998) using the 5% Duncan test, except for ovulation, the chi-square test was used. The internal temperatures of the animals varied according to the season (P <0.01), regardless of supplementation, this represents a high thermal load on the animals on pasture and there is already a difficulty for the animals to dissipate this heat, which can trigger physiological responses. The animals supplemented during the rainy season showed higher consumption of dry matter from pasture, PB, MM, NDT, FDN, FDA and EE (P <0.01), while cows in the dry period showed less consumption, such facts have relationship with rumen dynamics that had a positive influence with supplementation. T3 and ketone bodies did not show significant differences (P> 0.1), but cortisol and T4 showed a trend of variability (0.1> P> 0.05), corroborated by the high standard error by the effects of supplementation and season, which may denote physiological responses to the thermal stress to which the animals were subjected. Follicular dynamics were also greatly affected by the season and supplementation, during the rainy season cows lasted 50 hours to ovulate, while in the dry period they took 65 hours (P <0.05). Ovulation showed a direct correlation with supplementation (P <0.05), increasing cases of anovulation in non-supplemented cows, and it was found that the follicular diameter was smaller (P <0.01) in non-supplemented cows, such facts they are directly related to less dominance, and less efficiency in follicular recruitment, causing lower rates of pregnancy of cows, regardless of the period of the year. Supplementation of dairy cows, whether in the dry or rainy season, increases the consumption of nutrients from dairy cows and improves reproductive efficiency, thermal stress affects the ovulation schedule, a factor that must be carefully observed in artificial insemination techniques in fixed time .

MEMBROS DA BANCA:
Externo à Instituição - CRISTIAN FATURI - UFPA
Externo à Instituição - EDUARDO SCHMITT - UFPel
Externo à Instituição - ELIZANGELA MIRIAM MOREIRA - UFAM
Presidente - 958.305.370-87 - LUIZ FRANCISCO MACHADO PFEIFER - EMBRAPA
Externo à Instituição - PEDRO GOMES DA CRUZ - EMBRAPA