Changes in body composition of sheep selected for high and low backfat thickness, during periods of ad libitum and maintenance feeding

Abstract

Link to this article: http://journals.cambridge.org/abstract_S1357729800015289How to cite this article: J. Afonso and J. M. Thompson (1996). Changes in body composition of sheep selected for high and low backfat thickness, during periods of ad libitum and maintenance feeding. AbstractCoopworth sheep from the high and low backfat selection lines and from one random-bred line developed at Invermay, New Zealand, were used to examine the interaction between the degree of fatness of sheep and a period of maintenance feeding (from 20 to 35 weeks of age), in terms of total fat, carcass lean tissue, bone and viscera weights, relative to the empty body weight measured in computer-aided tomography scans. A similar study was done for weights of subcutaneous, intermuscular and internal (abdominal) fat partitions relative to total fat weight. During two ad libitum feeding periods (front 10 to 20 and from 35 to 43 weeks of age) changes in the same components relative to the 'whole' (empty body weight or total fat, depending on the case) were expressed in allometric terms. Only the allometric growth coefficient for total fat weight was significantly affected by the period of restricted feeding, decreasing after this period. No line or sex effect was observed on any growth coefficient. As a result, there were no changes in differences between treatments over the ad libitum feeding periods, with fat animals and females having significantly higher proportions of fat, while females also had a significantly lower proportion of intermuscular fat. During maintenance feeding, line and sex differences in dissectible component weights did not change significantly, except in terms of intermuscular fat, with the males showing an increasingly larger proportion than the females.

Growth and distribution of non-carcass components of Small East African and F1 Norwegian crossbred goats under concentrate diets

“…Results from the present study showing that most fat depots had growth coefficient greater than one relative to EBW confirm the phenomenon that fat tissue matures late than other tissues in the empty body (Afonso and Thompson, 1996;Wood et al, 1999;Okeudo and Moss, 2007). Moreover, the higher allometric growth coefficient for non-carcass compared to carcass fat depot displayed in the present study is similar to the pattern observed in sheep (Mahgoub and Lodge, 1994).…”

“…Non-carcass fat matures later than carcass fat and hence the pronounced effect of concentrate supplementation in non-carcass compared to carcass depot during finishing period (Cameron et al, 2001;Negussie et al, 2003;Mahgoub and Lu, 2004). Afonso and Thompson (1996) working with sheep, however, reported the allometric growth coefficient of less than one for internal fat relative to TBF. The discrepancy in findings indicates the species difference in growth and partitioning of body fat.…”

“…Non-carcass fat, on the other hand, acts as protective pad for internal organs. Overall, both carcass and non-carcass fat depots serve as energy stores, providing a survival buffer against periodic food scarcity such as in drought (Afonso and Thompson, 1996;Negussie et al, 2003). Research findings show that, onset of fattening and distribution of fat in domestic animals is affected by breed and plane of nutrition (Wood et al, 1999;Sanudo et al, 1998;Andersen et al, 2005;Warren et al, 2008).…”

Adipose and skeletal muscle thermogenesis: studies from large animals

“…Over thousands of years of domestication, the modern sheep has undergone much human-imposed selection to the point that there exists polygenic populations predisposed to either obesity or leanness (Afonso & Thompson 1996, Morris et al 1997. Animals were originally selected for innate differences in adiposity by measuring back fat thickness and two lines were created via selective breeding strategies.…”

The role of promotion tools used in the Spanish campaign to promote new lamb meat cuts

“…En nuestro caso, a pesar de que como ya se ha indicado la raza no fue, globalmente, un efecto significativo, fueron los lechales y ternascos churros los que presentaron una carne más grasa, posiblemente por ser una raza más precoz y de pequeño formato (Zygoyannis et al, 1990, Sañudo et al, 1997 y aptitud lechera (Wood et al, 1980). En cualquier caso, hay que considerar que unas mayores edades y pesos están asociados a superiores estados de engrasamiento (Tabla 16) (Field et al, 1990, Zygoyannis et al, 1990, Aziz et al, 1993 aunque algunas veces las diferencias no sean significativas (Alfonso y Thompson, 1996) ya que estas diferencias son, dentro de una raza o cruce, más marcadas a unos pesos de sacrificio que a otros (Andrews y Ørskov, 1970) La grasa también influye en muchas características que califican la calidad del producto que se consume (Tabla 17), desde el color de la carne, hasta la percepción de su textura o de su sabor, ya que dependen de una u otra manera de la composición de la misma (Muchenje et al, 2009). Un mayor porcentaje de ácidos grasos insaturados se puede relacionar con un color más intenso y más amarillo debido a la mayor susceptibilidad a la oxidación por su mayor inestabilidad.…”