Siller, Amy Elizabeth (2017-07). Initial Assessment of Calf Performance and Cow Reproductive Traits in a Dominican Republic Beef Herd. Master's Thesis.
Thesis
The objective of this study was to establish a benchmark analysis regarding beef herd productivity in a private, commercial beef cow operation in the Dominican Republic. Historical records (approximately n = 4,000) from January 2002 to July 2016 were obtained; the majority of cows were Brahman crossbreds. Calf weaning weight (WWT, n = 1,905) was influenced (P < 0.001) by cow age, cow color, calf sex, and calf age at weaning covariate. Mean WWT was 183.9 kg at 230 days of age, with males 10.9 kg heavier than females. As expected WWT was lowest from two (151.6 kg) and three year old cows (164.0 kg), and peaked with eight year old cows (199.7 kg). There was no obvious pattern for differences in WWT due to cow color, and ranged from 180.2 to 190.6 kg with the exception of one color code. Weaning age had an overall negative effect on WWT with a regression coefficient of -0.33 +- 0.05 kg/d; however calf weaning age ranged from 153 to 293 days. Calving interval (CI, n = 567) and cow reproductive productivity index (CRPI, n = 794) were both influenced by cow age (P < 0.001), but not color code. The mean CI was 462 (SD = 66) days. Range in CI means across cow age were 413 to 508 days, but had no obvious pattern across ages. Four and nine year old cows had the shortest CI with a mean of 413 and 418 days, respectively. The mean CRPI was 0.91 +- 0.27. In general, CRPI became lower as cows got older, especially for cows 13 and older (0.68 +- 0.045). Cumulative cow expense and cumulative income from calf sales were estimated with means of $RD 45,419 and $RD 33,016, respectively, with an overall negative net return of $RD -12,403 (-261.42 US$). Lifetime net return per cow was variable (SD = $RD 13,149, CV = 106%), ranging from -91,061 to 31,530 $RD. In this herd cow reproduction and calf survival restricted economic efficiency, not calf size; CI and CRPI variability in this herd show that large improvements for economic measures are possible.
