Simulating the profitability of male-sexed semen use in extensively farmed beef cow herds

Abstract

Male-sexed semen can be used in beef cow herds to increase the number of heavier and faster-growing male offspring. The use of sexed semen requires artificial insemination (AI) which has limited use in extensive beef systems due to practical constraints and the additional breeding costs incurred. The objective of this study was to use bio-economic simulation modelling to predict the profitability of using sexed semen via fixed time AI for a New Zealand hill country farm system based around a beef cow herd. When modelling self-replacing Angus herds male-sexed Simmental semen was utilised across 43% of mixed-age cows then follow up Simmental bulls were used for subsequent natural mating. To generate replacement Angus heifers, first time calvers and remaining mixed-age cows were bred with unsexed Angus semen and then naturally bred with Angus bulls if they did not conceive. All mixed-age cows in an AngusxHolstein-Friesian herd with a bought-in replacements policy were bred with male-sexed Simmental semen followed by Simmental bulls. First time AngusxHolstein-Friesian calvers were bred with unsexed Angus semen followed by Angus bulls. Sire breed was assumed to have the same effects on offspring production regardless of use through AI or natural mating. Herds using sexed semen were assumed to undergo synchronised fixed-time AI which resulted in a more condensed calving spread and 3% heavier average weaning weights due to calves being predominantly male and on average seven days older. Total breeding costs were higher for herds using sexed semen via AI at NZD 135-166 /cow compared with NZD 67-102 /cow for herds using only natural mating. Increases in breeding costs were relatively larger than any additional income for all herds using sexed semen via AI, resulting in lower COS (cash operating surplus) compared with herds using all-natural mating. The COS of using sexed semen via AI were 14% (COS = NZD 280 /ha) and 9% (COS = NZD 405 /ha) lower than all-natural mating using Simmental sires for the purebred Angus (COS = NZD 325 /ha) and AngusxHolstein-Friesian crossbred (COS = NZD 444 /ha) cow herds, respectively. It appears producing more fast-growing male calves through use of sexed semen via AI is not currently an economically feasible option for beef producers under extensive production systems. Future analysis could include benefits of access to higher genetic merit sires as the combination of superior genes and more male offspring may be more profitable than all-natural mating.