Post- partum reproductive performance of Friesian cows in relation to season of calving and level of milk production
Abstract: To study the seasonal effect, the year was divided into two main seasons, the cold extending from November to April and the hot from May to October. Within each season, the animals were divided into two classes according to their level of milk production throughout the first 90 days of lactation as low yielder (<958kg, less than or equal to the herd average) and high ones (> 958kg, more than the herd average).
The experimental work of this study included two parts.
I) Estimating the post-partum reproductive efficiency parameters and the physiological activity, in 38 cows calving during cold (n=18) and hot (n=20) season. The studied parameters included number of services per conception (NS/C), conception rate (CR%) and days open (DO), whereas the physiological parameters were uterine involution period (UIP), post-partum ovulation interval (PPOI), post-partum estrous interval (PPEI) and types of ovarian and estrous activities. The cows were visually observed for estrous detection along with using a teaser bull two rounds daily at- 7:00 and 17:00 h. for 60 min. at each round.
Blood samples were collected at 3 to 4 days interval for plasma progesterone determination.
II) Describing the post -partum sexual behaviour development. This part included twelve of high yielder cows, calving during cold season. Cows were checked intensively every 8 hours (three times daily) for estrous detection, starting from 7:00 a.m.
Estrous detection procedure, blood sampling and progesterone determination were similar to those of the first experiment.
The obtained results could be summarized as follow:
1- The overall mean of the conception rate from the first service, number of services per conception and the days open length were 20%, 3.2±0.5 and 134.1:t21.5 days respectively.
Cold season showed a significant adverse effect on the CR %, NS/C and DO comparable to those obtained in hot season. These parameters were 17.6%, 4.1±0.5 and 182.7±21.9 vs. 22.2%, 2.4±0.5 and 85.5±21.1 for cold and hot seasons, respectively.
3-. Deference between high and low yielder was observed in the CR% and NS/C (26.7%, vs. 15.0% for high and low yielder respectively). However, no difference were observed in to DO length and NS/C (131.7 and 3.3±0.6 vs. 136.6 and 3.2±0.5 for high and low yielder, respectively).
The overall means of VIP, PPOI and PPEI were 29. 9± 1. 5, 52.5±6.4 and 51.5±5.3 days, respectively. The shorter PPEI than to PPOI is due to the incidence of many cases of false estrus.
Cold season environment has an adverse effect on the resumption of ovarian activity. The average of PPOI for cold and hot season was 62.6±6.6 and 43.1±6.2 days, respectively. Such effect was not observed in VIP where the average of both season was almost equal (about 30 days).
6- Low yielder possessed shorter VIP and PPOI averaging 28.5±l.4 and 43.2±6.0 days vs. 31.4±1.6 and 62.6±6.8 days for high yielder, respectively. A reverse trend was observed for PPEI averaging 45.l±5.7 vs. 57.8±4.9 for high and low yielder respectively.
The percentage of quiet ovulation incidence was 38.8% and 30.8% in cold and hot season, respectively. Types of ovarian dysfunction
percentage 61.1 % and 20.0% for the two seasons, respectively throughout the experimental period.
8- The percentage of quiet ovulation incidence was 24.3% and 40.7% for high and low yielder cows, respectively. The percentage of ovarian dysfunction was 53.3% and 42.9 for two yielder groups, respectively.
9- The overall mean of heat duration was 13. 6± 1.1 hours, it increased with ovulation repetition. The occurrence of weak and moderate heats decreased from 28.6% and 57.1 %, respectively in the first heat to 12.5% and 37.5, respectively in the subsequent ones. A reverse trend was found for strong heat cases (14.2% in the first estrus to 50% in the subsequent ones).
10- Inereasing heat detection rounds per day improved the heat detection efficiency to be 87% vs. 54% for three and two rounds of heat detection / day, respectively.
Publication year 1997
Pages 153p.
Availability location مكتبة معهد بحوث الانتاج الحيوانى- شارع نادى الصيد- الدقى - الجيزة
Availability number 545
Organization Name
Country Egypt
Department Biotechnolog Research Department
Author(s) from ARC
Agris Categories Animal physiology - Reproduction
AGROVOC
TERMS		 Cold season. Cows. Milk production. Oestrus detection. Parturition. Perinatal period. Reproductive performance. Seasons.
Publication Type PhD Thesis
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