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Association between age at first calving and economic performance of replacement dairy heifers.

M. Masello



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Association between age at first calving and economic performance of replacement dairy heifers.
M. Masello*1, M. M. Perez1, G. E. Granados1, M. L. Stangaferro1,2, B. Ceglowski2, M. J. Thomas2, J. O. Giordano1. 1Department of Animal Science, Cornell University Ithaca, NY, 2Dairy Health and Management Services Lowville, NY.

Our objective was to evaluate the association between age at first calving (AFC) and the economic performance of Holstein replacements. Nulliparous heifers (n = 1,144) from 3 farms were eligible for AI at 368 � 10 d of age [beginning of the AI period (AIP)]. Sexed semen was used for first AI and conventional semen for second and greater AI. After calving, heifers were retrospectively assigned to 1 of 3 groups based on AFC tertiles within farm: Low (n = 391): 20.2—21.8 mo, Medium (n = 376): 21.4—22.8 mo, and High (n = 377): 22.1—28.7 mo. Individual heifer costs and revenues were collected for 15 mo after the beginning of the AIP [rearing period (RP) and part of the first lactation (FL)]. Total cash flow (CF) was the aggregation of RP reproductive cost (RC), RP feed cost (FDC), RP fixed cost (FXC), calf value (CFV), FL income over feed cost (IOFC), FL replacement cost (RPLC), and FL FXC. Binomial and quantitative data were analyzed by logistic regression and ANOVA, respectively. All results are in Table 1. Differences in AFC among groups were explained by differences in age and P/AI at first service. All RP costs were greater with increasing AFC. Similarly, most FL parameters favored heifers with low vs. high AFC whereas heifers with medium AFC had intermediate performance. We conclude that the profitability of replacement heifers during a 15-mo period after the beginning of the AIP increases as AFC decreases.Table 1. Reproductive and economic outcomes

Age 1st AI (d)371 � 0.5a376 � 0.5a378 � 0.5b<0.01
P/AI 1st AI (%)95.9a33.2b0.27c<0.01
RP (d)276 � 5.7a301 � 5.7b352 � 5.7c<0.01
FL (d)180 � 5.7a155 � 5.7b104 � 5.7c<0.01
Rearing ($/heifer)
 RC39.9 � 0.9a57.0 � 0.9b94.6 � 0.9c<0.01
 FDC533 � 13a587 � 13b705 � 13c<0.01
 FXC235 � 4.8a256 � 4.8b300 � 4.8c<0.01
Total RP cost807 � 22a900 � 22b1,099 � 22c<0.01
First lactation ($/heifer)
 CFV97.8 � 1.8a96.7 � 1.8ab92.5 � 1.8c0.05
 IOFC980 � 58a850 � 58b583 � 58c<0.01
 RPLC68.9 � 1360.1 � 1351.2 � 130.58
 FXC557 � 18a480 � 18b321 � 18c<0.01
Total FL profit454 � 45a408 � 45a304 � 45b<0.01
CF 15 mo−354 � 63a−492 � 63b−795 � 63c<0.01

Keywords: profitability, age at first calving, dairy heifer.

Biography: Magdalena Masello obtained her DVM degree in 2014 from the University of the Republic in Uruguay. In 2016 she started her PhD program at Cornell University's Department of Animal Science working in Dr. Julio Giordano's laboratory. Her research is focused in dairy cattle reproductive physiology and management.