Author(s)

José Francisco Martínez¹, Pablo Ortiz¹, Carlos Salvador Galina¹, Manuel Corro², Ivette Rubio², Libia Pérez-Torres^3*

¹Departamento de Reproducción, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Ciudad de México, México.
²Centro de Enseñanza, Investigación y Extensión en Ganadería Tropical, Facultad de Medicina Veterinaria y Zootecnia, Universidad Nacional Autónoma de México, Tlapacoyan, México.
³Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Tamaulipas, Ciudad Victoria, México.

A comparison between two distinct levels of back fat thickness in open cows, females not becoming pregnant during the previous breeding season, was carried out in order to evaluate their reproductive performance prior to the next natural mating in a seasonal breeding program. Thirty open cows from the previous breeding season were divided evenly by age and back fat thickness (BFT) in two groups. HBFT (high back fat thickness ≥ 70 mm) and LBFT (low back fat thickness ≤ 70 mm), values statistically different between groups (P < 0.05). The study was divided into three phases in which the formation of CL and follicular dynamics were recorded by ultrasound and progesterone. Also, serial monitoring of glucose, urea and triglycerides and back fat thickness were studied. A fertile bull previously approved from a breeding soundness evaluation was introduced after the third phase and remained with the herd for 90 days. No differences were found in the follicular dynamics; the number of animals cycling in the two groups and fertility were also similar (80%). Differences in urea and triglycerides were found in cows with high scores of BFT. In conclusion, the decision of keeping open cows to the next breeding season must be based on an economical advantage to the farmer.

Back Fat Thickness, Corpus Luteum, Follicular Dynamics, Tropics, Zebu Cattle

Martínez, J. , Ortiz, P. , Galina, C. , Corro, M. , Rubio, I. and Pérez-Torres, L. (2022) Open Cows in a Beef Cattle Enterprise Managed in a Seasonal Breeding Program? An Appraisal of Their Reproductive Performance Based on Body Fat Reserves. Open Journal of Veterinary Medicine, 12, 37-48. doi: 10.4236/ojvm.2022.125005.