Comportamiento productivo de vacas F1 Holstein-Brahman en un rebaño lechero: crecimiento, eficiencia reproductiva, producción de leche y causas de eliminación
A population of F1 Holstein-Brahman cows belonging to a dairy herd located in Cojedes state was studied, aiming to characterize their growth, reproductive efficiency, milk production and elimination causes, using the following characteristics: Daily weight gain (GDP), milk production (PTOTAL and PL2...
Zapisane w:
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2017
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| Hasła przedmiotowe: | |
| Dostęp online: | http://hdl.handle.net/10872/16632 |
| Etykiety: |
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| Streszczenie: | A population of F1 Holstein-Brahman cows belonging to a dairy herd located in Cojedes state was studied, aiming to characterize their growth, reproductive efficiency, milk production and elimination causes, using the following characteristics: Daily weight gain (GDP), milk production (PTOTAL and PL244), lactation duration (DL), calving interval (IEP) and production per day of IEP (PDIEP), analyzed using descriptive statistics and analysis of variance to determine which non-genetic factors affect them. The causes of cows elimination by descriptive analysis and also the correlation between the relative value of milk production (VRPTOTAL and VRPL244) of F1 females and the average relative value of weaning weight of the Brahman cows (VRP). For the analyzes, 1279 observations were used for PTOTAL, PL244 and DL, 836 for IEP and PDIEP, 565 and 323 for EPP and GDP respectively, 774 for elimination causes and 581 for VRPTOTAL/P244-VRP correlation. The descriptive statistics and the VRPTOTAL/PL244-VRP correlation were performed using the Statistix® statistical package and the analysis of variance using the maximum likelihood (ML) methodology, using the SAS® statistical package (Littell et al., 2002) with an additive linear model with fixed and random effects. The fixed effects included in the models were: year of birth (AN), age to calving (EM/EP), month of birth (MN), year of birth (AP), season of birth (EPOP), varying each model with some interactions. The bull father effect was included as random in the PL244, PDIEP and GDP models. In the IEP model the PTOTAL covariate was included. A Tukey test was performed on the adjusted means of significant effects. The adjusted means obtained were: 2613.1 kg for PL244, 378.2 d for IEP, 8.4 kg/day for PDIEP, 27.6 months for EPP and 0,800 kg for GDP. In the case of PTOTAL and DL the unadjusted means were 3148.9 kg and 243.0 d respectively. The AP affected (P <0.01) to PL244, IEP and PDIEP, the EP only affected (P <0.01) the IEP, while the EPOP affected (P <0.01) to PL244 and PDIEP. The AP*EP and EP*EPOP interactions affected (P <0.05) both PDIEP and PL244 respectively, whereas AP*EPOP affected (P <0.01) both PL244 and IEP. For EPP and GDP it was obtained that the AN had effect (P <0.01) for both characters, EM only affected (P <0.05) to GDP and finally the interaction AN*MN affected (P <0.05) to EPP. It was found that 36.4 % of the females entering the milking herd were eliminated, being the most important the low milk production, mastitis and low reproductive efficiency. It was observed that more than 60 % of the eliminations were in cows with two lactations or less. The correlation values between VRPTOTAL/PL244 and VRP obtained were close to zero (0.0645 and 0.0879, respectively), being statistically significant only the correlation between VRP244 and VRP. The results indicate that the F1 Holstein-Brahman females studied presented acceptable behavior for the conditions in which they are producing, since the values of both milk production and reproductive efficiency are equal to or higher than other values reported in the literature. However, to be able to take advantage of this potential, it is necessary to provide adequate conditions for its proper development and during its productive stage, to being highly productive, it is equally demanding and susceptible to environmental changes. |
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