Growth Curves of Texel Male Lambs

Abstract

Background: The consumption of lamb meat is growing due to improved farming methods. However, to be economically feasible, the animal should stand out for its precocity, fast finishing and muscular force, such as seen in Texel breed. Besides, knowledge about weight gain and development can facilitate the selection of the best animals, and allow a better fitting to farming systems. Growth curves are an effective method that describes animal development, modeling the relationship between weight and age and help to predict the growth rate. Thus, this study aimed to analyze which nonlinear model, including Brody, Gompertz, Von Bertalanffy and Logistic best describe the growth curve of Texel sheep.Materials, Methods & Results: In this experiment, the lambs were kept in confined system while the ewes, in a semi-extensive system. This study followed 42 Texel male lambs, which were confined from birth to slaughter, and fed concentrated feed (3% of body weight) and corn silage (average 1.5 kg/animal/day), 4 times a day. The lambs were weighed fortnightly, in different classes considered as follows, weight at birth (BW), 15 days (P15), 30 days (P30), 45 days (P45), 60 days (P60), 75 days (P75), 90 days (P90), 105 days (P105), and 120 days (P120), which was defined as the slaughtering weight. The growth curves were determined using the nonlinear models of Brody, Von Bertalanffy, Gompertz and Logistic. The following parameters were used in the curves, Y, slaughtering weight; A, asymptotic weight; k, growth rate, t, animal age; B, constant related to the initial weight; and, m, constant of the curve shape. The criteria used for selecting the model that best described the curve were the mean square error (MSE), which was calculated by dividing the sum of squared error by the number of observations, and also the coefficient of determination (R²), calculated as the square of the correlation between the observed and estimated weights. The average weights observed were as follows, 4.02 kg at birth, 21.68 kg at weaning (P60) and 32.55 kg at slaughtering (P120). The solution of the nonlinear models allows, thru the parameters, establish specific feeding programs and define the optimal slaughtering age. Furthermore, the coefficients of determination, with values close to 97.3%, showed good fits for all models. Still, considering the mean square error, where the lower value indicates the best fit to the data evaluated, the results were 13.1564 (Brody), 13.3421 (Von Bertalanffy), 13.4876 (Gompertz) and 13.6717 (Logistic). The results showed that Brody could be considered the model that best describes the growth rate up to 120 days old of Texel lambs.Discussion: Compared to other studies, the average weights obtained in the experiment varied widely. This large variation can be explained by the used rearing system that might favor or not the performance of lambs. However, the average weaning weight obtained was similar to several studies in the literature, confirming the potential of Texel breed. This breed demonstrated to be capable to provide a precocious animal, with good growth results from the early developmental stage until the slaughtering age. Regarding the growth curves, the Brody model was the best fit for the estimated and observed weights. Moreover, the coefficient of determination indicated good fits for all models. However, an important aspect is the negative correlation between the A and k parameters, demonstrating that the higher the animal growth rate, the lower its asymptotic size.

Influence of Nigella sativa Oil on Growth Performance and Feed Utilization and Comparison of different Non-Linear Functions against Linear Model to Describe the Growth Curve in Nile Tilapia

“…Different non linear functions were used to describe growth curve in the present study such as Von Bertalanffy model, Weibull model and Morgan-Mercer-Flodin model in addition to linear model. Different authors in different studies reported that non linear models gave highest accuracies in the description of growth curve (Esenbuğa et al, 2000;Lewis et al, 2002;Bilgin and Esenbuga, 2003;Topal et al, 2004;Tekel et al, 2005;Tariq et al, 2013 andSieklicki et al, 2016).…”

“…Results in Table 8 showed the different parameters along with their standard error for different growth models fitted to body weight in Nile tilapia (Oreochromis niloticus) reared on diets with different levels from Nigella sativa oil. Sieklicki et al (2016) reported that the knowledge of the different parameters for non linear models is very important to establish specific feeding managements and determine the marketing age.…”

“…Nowadays, medicinal herbs are becoming more popular than ever before as far as the possible adverse effects of synthetic drugs are concerned (Rawling et al, 2009;Bilen et al, 2011Bilen et al, , 2013Bilen et al, and 2014. Several studies demonstrated positive effect of medical herbs and oil on growth performance and feed utilization in different types of fish (Dias, 2002;Metwally, 2009;Abdelwahab and El-Bahr, 2012;Sönmez et al, 2015).In connection to growth curve, numerous growth equations have been fitted to describe the nonlinear relationship between growth and age of animal such as Brody, Morgan-Mercer-Flodin, weibull, Gompertz, Logistic and Von Bertalanffy models (Tekel et al,2005;Tariq et al, 2013;Sieklicki et al, 2016).The objective of the present study is to investigate the effect of different dietry levels of Nigella sativa oil on growth performance and feed utilization in Nile tilapia (Oreochromis niloticus) and comparison of different nonlinear functions to describe growth curve against linear function.…”

Growth Curves in Lambs of Various Genotypes Created on the Basis of Improved Valachian and Tsigai Breeds

“…Growth intensity of lambs before weaning and after weaning significantly affects the economics of farming (Petr et al, 2009;Pajor et al, 2008;2009a;Wolfová et al, 2009;Komprda et al, 2012;Svitáková et al, 2014;Koutná et al, 2016). The growth is affected by many factors where the most important are the breed, nutrition, sex, litter size, management, biotic stress, health and age of mothers (Kuchtík and Horák, 2007;Dobeš et al, 2007;Hošek et al, 2008;Pajor et al, 2007;2009b;Kuchtík et al, 2010;Zapletal et al, 2010;Štolc et al, 2011;Ptáček et al, 2013;Lupi et al, 2015;Waheed et al, 2015;Aguirre Riofrio et al, 2016;Mellado et al, 2016;Moreira et al, 2016;Sieklicki et al, 2016).…”