A comparison of the growth performance between cattle reared in conventional systems and in feral conditions

Abstract

Feral and conventional growth performances were compared using Marismeña cattle as a model. Marismeña calves are commonly reared under feral conditions in one of the most important reserves of Europe (Doñana National Park, Spain). Data recording in these natural conditions faces compromises as animals are only handled once per year. This fact has to be saved to obtain efficient estimations for the biological growth curve of cattle reared under feral conditions. On the one hand, we assessed the inference of the theoretical influence of human management on cattle growth. On the other hand, we studied the fitness of the best growth curve, in both feral and conventional systems to use the physiological meaning of the parameters obtained from their study as selection criteria related to the adaptability of potential breeding males and females. Fitting of Brody's, von Bertalanffy, Verhulst, logistic, Gompertz and Richards' models was tested as these models are the most representative ones for cattle growth. In general, Brody's and Richards' models presented the best fitting values for the biological curve. According to the biological curve parameters, males and females presented asymptotic weights of 641.71 kg and 403.55 kg, respectively. As expected, the results of the commercial growth curve severely differed from those of the biological curve. The best fitting biological curve was not representative for cattle reared under commercial conditions. The logistic model was the best fitting one for feral females, Gompertz model for feral males, and Verhulst for intensive males and females, respectively. Seasonal oscillations in feeding may be responsible for the earlier achievement of the best performance in feral cattle (7 and 10 months for males and females, respectively), while such best performances were reached at 11 months in intensive calves, what becomes relevant for management and slaughtering decision-making. The study of the biological curve in Marismeña feral breed is very illustrative as this is the first time that feral cattle's growth is approached. Knowledge on the biological growth curve parameters could be used to interpret the strong relation between feral animals and their environment. This research could infer a model to quantify the effects of human management on livestock development, as feral resources offer unique opportunities to study domestic livestock without any human influence.

Comparison of non-linear models to describe the growth in the Andalusian turkey breed

“…In this regard, the growth rate becomes altered as the animal reaches its adult size, which translates into an appreciable change in curve shape where the highest growth rate occurs (inflection point). Afterward, the growth rate decreases and stabilises describing a continuous trend, which mathematically coincides with a horizontal asymptote (Narinc et al 2017;Nogales et al 2017).…”

“…Table 2 presents the functions for the seven non-linear models selected in the present study which were namely; Richards, Brody, Logistic, Verhulst (a variant of Logistic model), Gompertz, Sinusoidal, and Von Bertalanffy (Ersoy et al 2006;Nogales et al 2017;Kuhi et al 2019). The fitting procedure was developed using multiple observations of the dependent variable (weight) for each point of the independent variable (day of life).…”

“…Similarly, Brody model has been deemed as inappropriate to fit for growth performance in other species (Lupi et al 2015). Conversely, Brody model may be rather efficient to accurately predict growth in other species at older ages (G omez et al 2007), such as cattle (Nogales et al 2017).…”

“…However, native turkey breeds have developed a genetic resistance to some diseases as a consequence of greater diversity which provides them with greater resistance than commercial lines (Kamara et al 2007;Camacho-Escobar et al 2008), since heterogeneous populations are less susceptible to viral infections (Mpenda et al 2019). In addition, in the last years, there has been an increasing interest in food produced under environmentally sustainable conditions, for which native breeds have a great potential (Nogales et al 2017).…”

Characterisation of biological growth curves of different varieties of an endangered native hen breed kept under free range conditions

“…Within the cycle life of animals, the total growth duration can be divided in three phases: an acceleration phase, a deceleration phase, and a stabilisation phase for ripening (Nogales et al 2017). So, growth pattern usually is typically fitted by models with sigmoidal structure.…”