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This study was conducted to evaluate and compare the economic benefits of different embryo sexing methods, based on the cost per female dairy calf produced. Female calves were produced from four kinds of female embryos: (1) those collected from superstimulated donors at 7–8 days after artificial insemination (AI) with X-sorted semen; (2) those sex-determined by loop-mediated isothermal amplification assay of a biopsy sample of embryos collected from superstimulated donors after AI with conventional unsorted semen; (3) those obtained by invitro embryo production (IVEP), using X-sorted semen and in vitro-matured oocytes collected from donors by ovum pick-up (OPU); and (4) those obtained by IVEP, using X-sorted semen and oocytes collected by OPU after dominant follicle ablation and follicle growth stimulation of the donors. The respective productivities of female calves per technical service and the total production cost per female calf of each sexing method were compared. The production cost per female calf (66,537 JPY), as calculated from the number of female calves per service (1.30), pregnancy rate of transfer (42.9%), rate of female calves obtained (92.9%), and total cost of the method (56,643 JPY plus embryo transfer fee), was less for IVEP with X-sorted semen and follicular growth-stimulated (FGS) oocytes than for the other groups (P < 0.05). The results demonstrate that embryo production with X-sorted semen and FGS oocytes provides a more efficient method for producing female calves than the other embryo sexing methods.

The use of sexed semen to produce purebred replacement heifers allows a large proportion of dairy cows to be mated to beef sires, and quantitative and qualitative improvements to be made to beef production from dairy herds. The major dairy and beef breeds are undergoing rapid genetic improvement as a result of more efficient selection methods, prompting a need to evaluate the meat production of crossbred beef × dairy cattle produced using current genetics. As part of a large project involving 125 commercial dairy farms, we evaluated the combined use of purebreeding with sexed semen and crossbreeding with semen from beef sires, particularly double-muscled breeds. A survey of 1,530 crossbred calves revealed that, whereas purebred dairy calves are destined almost exclusively for veal production, beef × dairy crossbred calves are also destined for beef production after fattening on either the dairy farm of birth or by specialized fatteners. In veal production, compared with Belgian Blue–sired calves (taken as the reference), double-muscled INRA 95–sired calves had a lighter slaughter weight (303 vs. 346 kg), but a greater dressing percent (62.3 vs. 58.4%). Limousin (also known as Limousine)–sired calves had a smaller average daily gain (1.26 vs. 1.34 kg/d), and lighter slaughter (314 vs. 346 kg) and carcass weights (182 vs. 201 kg). Last, Simmental-sired calves had a similar growth rate, but lighter carcass weight (177 vs. 201 kg), smaller dressing percentage (55.3 vs. 58.4%), and smaller muscularity scores (3.25 vs. 3.72). In the case of young bulls and heifers fattened on the dairy farm of birth, Belgian Blue–, Piemontese (also known as Piedmontese)-, and Limousin-sired calves performed similarly; the only exception was that Piemontese-sired calves had a greater dressing percentage. Belgian Blue– and Limousin-sired calves performed similarly when fattened by specialized beef producers. In both veal and beef production, the effects of dam breed were less important than sire breed. Considering the entire project, we can conclude that the combined use of sexed semen for purebreeding and conventional beef semen for terminal crossbreeding improves meat production from dairy herds, especially when the sires are double-muscled beef breeds. [ABSTRACT FROM AUTHOR]

The use of sexed semen to produce purebred replacement heifers allows a large proportion of dairy cows to be mated to double-muscled sires and for quantitative and qualitative improvements to be made to beef production from dairy herds. A survey of 1,285 crossbred calves showed that they are destined not only for veal production (like purebred dairy calves) but also for beef production. Crossbred calves obtained from Belgian Blue sires (sold on average at 34 d of age and 64 kg of weight) had a higher market value (€363/calf) than those obtained from double-muscled INRA 95 sires (€297/calf, used for veal production) and from Limousin sires (€216/calf for veal and €271/calf for beef production). As a sire breed, Simmental did not differ significantly from Belgian Blue, but as a dam breed, the crossbred calves fetched a higher price (€5.11/kg) than when Holstein was the dam breed (€4.50/kg). Compared with heifer calves, crossbred bull calves at sale were younger (34.1 vs. 37.2 d) and heavier (64.0 vs. 62.6 kg of live weight), fetched a higher price (€5.13 vs. €4.99/kg), and had a greater value (€328 vs. €312/calf). As the value of purebred dairy calves was about €80 to €100/calf, we are able to confirm that the combined use of sexed semen for pure-breeding and conventional beef semen for terminal crossbreeding can increase the income from dairy farms, especially when the sires are double-muscled beef bulls. [ABSTRACT FROM AUTHOR]

Using sexed semen to produce purebred replacement heifers makes it possible to mate a large proportion of dairy cows to double-muscled sires and to quantitatively and qualitatively improve beef production and increase the income from dairy herds. Net profit first depends on changes in the farm's overall fertility rate. The objective of this study was to analyze the conception rate in herds using a combination of conventional dairy semen (for pure- and crossbreeding), X-sorted dairy semen (to produce purebred replacement heifers), and conventional beef semen (for terminal crossbreeding). Data were obtained from 50,785 inseminations of 15,580 dairy cows (78% Holstein-Friesian, 15% Brown Swiss, 2% Simmental, and 5% crossbreds) from 106 dairy farms (average milk yield 35.1 ± 9.4 kg/d, with 3.76 ± 0.83% fat and 3.32 ± 0.39% protein contents). To account for the main potential confounders, we used separate generalized linear mixed-effects models for cows and virgin heifers. The results showed that the odds ratio of conception improved (1.00 to 1.34) with an increase in the average milk yield of the herd but worsened (1.12 to 0.70) with an increase in the milk yield of individual cows within herd. The summer months showed a strong reduction in the odds ratio of conception in cows (0.56 in July and August) but not in virgin heifers. Multiparous cows had a lower odds ratio of conception (0.85) than primiparous cows (1.00). The order of insemination did not affect the fertility of the cows or heifers, whereas the odds ratio of conception improved with advancing lactation (1.00 to 2.12). The Simmental cows were more fertile than Holstein-Friesians (1.37 vs. 1.00), whereas the fertility of the heifers was not affected by breed. Taking all these possible confounders into account simultaneously, in pure-breeding the odds ratio of conception using sexed semen did not differ from that using conventional dairy semen in cows (0.90 vs. 1.00) or in virgin heifers (0.95 vs. 1.00). However, crossbreeding using conventional beef and dairy semen improved the odds ratio of conception (1.10 and 1.17, respectively) in cows (1.37 using beef semen) and heifers (1.25 using dairy semen). The proportion of newborn heifer calves was ≥90% using sexed dairy semen. The combined use of sexed semen, especially on heifers, to produce purebred replacement females and beef semen to produce terminal crossbred calves was shown to have the potential to increase overall herd fertility, which could be further improved using sexed dairy semen to produce dairy crossbreds instead of purebred replacement heifers. [ABSTRACT FROM AUTHOR]