Longevity of Nelore Cows of the Bolivian Tropics. Is It Possible to Explain It Through Productive Variables?

Abstract

The objective of this work was to evaluate the longevity and its relationship with productive variables of Nelore cows in grazing systems of the Bolivian tropics. Retrospective data were used corresponding to 259 Nelore breed cows, primiparous and multiparous discarded with a total of 800 births, in the period between 2005 and 2019, belonging to the Cooperativa Agropecuaria Integral San Juan de Yapacaní (CAISY) located in the San Juan Japanese Communities, Santa Cruz, Bolivia. The variables analyzed were: Live weight of cow (WC) in kg, Weight of the calf at birth (WCB) in kg, Weight of calf at weaning (WCW) in kg, Total weight of weaned calf (WWC) in kg, Age at first calving (AFC) in months, Number of calvings (NC), Longevity (L) in days, Calf Index (CI) in kg, Accumulated Productivity (PAC) in kg, Total calf production (CP) in kg, Efficiency of Stock (ES) in kg. In order to respond to the main objective of this work, the relationship between the life longevity of the cow and the other productive variables was studied. For this, first principal component analysis (PCA) was carried out, by means of which the space dimension of the productive variables was reduced creating new linearly independent variables and in this way avoid problems of multicollinearity in the model, because the productive variables in some cases turned out to be correlated. Then, the first three main components that explain 77% of the total variability of the data were retained and interpreted as follows: The PC1 was high and directly correlated with the variables NC, Kg produced total, % of stock efficiency, PAC and Kg produced meat / day, therefore can be thought of as an indicator of "productive efficiency". PC2 was an indicator of "efficiency in rebreeding" since it presented altar and direct correlations with WC and AFC. PC3 was high and directly correlated with birth weight and weaning weight, which is interpreted as an indicator of "breeding efficiency". Finally, a multiple linear regression model was adjusted considering Longevity as a function of productive efficiency, breeding efficiency and rebreeding efficiency (p-value <0.0001 in the three cases). 87% of the total variability of L (days) is explained by the model. It is concluded that Longevity is related to productive indicators for this group of Nelore cows in grazing systems of the Bolivian tropics.

Evolution of Production Indicators over Time in Nelore Cows from the Bolivian Tropics

“…The values found in the age at first calving were similar to those reported by Flores & Ortiz (2010), the live weights of the cows to those reported by Segura-Correa, Magá n-Morforte & Centruion-Castro (2013), the calf weights at birth and at weaning above those shown by Santana et al (2012); Boligon, Brignardi Mercadante Lobo & Albunquerque. (2013); Chud et al (2014); Ikeda et al (2019).…”

“…The use of aggregated or integrated indicators in the beef-breeding systems for meat would allow evaluating the behavior of both the genotypes or racial groups involved, as well as the impact of the management strategies (non -genetic) on the biological and economic efficiency of the systems involved. Ikeda, Barbona, Hayashi, Pereira & Marini (2019) raised the need to use indicators of this nature that help to avoid the overvaluation of a character to the detriment of all those involved, allowing to identify the biotypes most adapted to the different environments existing in the place of evaluation.…”

Number of Calving and Its Relationship with Productive Indicators in Nelore Cows

“…There is a need to use aggregated or integrated indicators in the cow-breeding systems for meat, because it would allow the evaluation of the behavior of both the genotypes and racial groups involved as well as the impact of the management strategies (non-genetic) on the both biological and economic [21] here using indicators of this nature would help to avoid the overvaluation of one of the characters involved in the characterization of a suitable cow for meat and would allow identifying the biotypes most adapted to the different environments existing in the place of evaluation. This is demonstrated with Figs.…”

Relationship of Longevity with Productive and Reproductive Variables in Nelore Cows of the Bolivian Tropic

“…In addition, the production of beef cattle is influenced, among other factors, by the genotype of the animal associated with the environmental conditions to which it is subjected (Holgado and Rabasa, 1999). A previous work by (Ikeda et al, 2019), showed results on the relationship between the longevity of the productive variables, in this case the parturitionparturition interval is introduced as a reproductive variable and a greater number of years of information to be able to continue deepening the understanding of why some cows live longer than others.…”