Performance and Quantitative Traits of Lamb Carcass of Three Subcutaneous Fat Thicknesses on the Loin

Abstract

The objective of this study was to evaluate productive and economic performances and quantitative carcass characteristics of ½Dorper + ½Santa Inês (½D-SI) and purebred Santa Inês (SI) lambs slaughtered with different subcutaneous fat thicknesses (SFT). Thirty-four lambs (16 SI and 18 ½D-SI) were confined and fed a total diet for an average daily weight gain of 0.300 kg. The subcutaneous fat thickness was measured by ultrasound (between the 12th and 13th ribs) and weekly weighing, and the lambs were slaughtered as they reached the pre-established SFT of 2.0, 3.0 and 4.0 mm. Breed group had no effect on productive performance. With regard to SFT, the final body weight was highest in the animals slaughtered with 4.0 mm. The economic evaluation provided an increasing net income with increase in SFT. The commercial and true yields were affected by the SFT at slaughter. For the cuts, the yield of the loin of crossbred animals was higher than that of Santa Inês lambs. The loin measurements showed no difference between breed groups. The lambs slaughtered with 2.0 and 3.0 mm of fat thickness presented the best feed conversion; however, those slaughtered with 4.0 mm of fat thickness had better economic results.

Allometric growth of ½ Dorper + ½ Santa Inês lambs slaughtered with different subcutaneous fat thicknesses

“…A similar growth rate was observed for the Cornigliese breed, with differences regarding gender and a proportional development of the head (Sabbioni et al, 2018). However, for lambs of other breeds finished in confinement (Furusho-Garcia et al, 2006) and slaughtered with different SFT (Mora et al, 2014), the neck cut showed isogonic growth. The shoulder cut presented a fast growth rate (β < 1) in relation to the development of the half carcass in lambs with 2.0 and 4.0 mm SFT.…”

“…Unlike the other half-carcass cuts, the rib presented an isogonic growth in lambs slaughtered with 2.0 and 3.0 mm SFT. This same type of growth was observed for confined Texel x Ile de France (Galvani et al, 2008) and Pantaneiro (Mora et al, 2014) lambs, being considered unrelated to race. In the present study, an opposite result (β <1) was found for lambs slaughtered with 4.0 mm SFT.…”

“…Lambs slaughtered with 2.0 mm SFT showed a negative heterogeneous growth (β <1) in the leg in relation to the half carcass. However, when the SFT of the lambs increased to 3.0 and 4.0 mm, the growth rate of this cut decreased, becoming isogonic, as verified for the leg growth of female Pantaneiro lambs (Mora et al, 2014). This allows inferring that smaller breeds are more precocious than larger ones (Figueiredo et al, 2019), especially regarding fat deposition (Van der Merwe et al, 2020).…”

“…An important parameter to obtain quality meat is body weight; however, it should not be the only criteria used for slaughtering (Osório et al, 2012), since lambs of different breeds with similar weights still present varying amounts of tissue deposition, which influences carcass characteristics (Camacho et al, 2015). The measurement of subcutaneous fat thickness (SFT) with the real-time ultrasound technique can be used as an indicator of the best time for the slaughter of lambs (Nascimento et al, 2018), as SFT allows predicting the composition and relative growth of other carcass cuts and tissues (Wood et al, 1980;Teixeira et al, 2006;Mora et al, 2014).…”

“…Allometry allows to better understand the growth rate and development of carcass regions, serving as a reference for a more precise slaughter time for each genetic group (Hashimoto et al, 2012). Although there are allometry studies related to sex, termination system, animal morphology, and SFT (Hashimoto et al, 2012;Mora et al, 2014;Sabbioni et al, 2018), the specific relative growth of ½ Dorper + ½ Santa Inês lambs slaughtered with different SFTs has not yet been evaluated. This crossing has shown reduced slaughter time, being an alternative for the production of sheep meat (Issakowicz et al, 2018).…”