Effect of different feed restriction regimens on lamb performance and carcass traits

Abstract

-Fifty Najdi ram lambs weighing an average of 38.1±0.5 kg were utilized in this study to determine the effects of feed restriction level with or without subsequent realimentation on lamb performance and carcass composition. Lambs were allotted randomly and equally into five groups. The groups were fed a control diet ad libitum; two groups fed 0.90 and 0.80 of ad libitum intake throughout the eight-week period of the trial (R), and two groups fed 0.90 and 0.80 of ad libitum intake for a six-week period followed by two weeks of realimentation (RR). All lambs were slaughtered after eight weeks of experimentation. Average daily gain (ADG) for the 0.90 and 0.80 ad libitum groups decreased by 7.6 and 26.9% during restriction, whereas the lambs during realimentation period had 35 and 30.5% faster ADG and 27.5 and 21.8% better feed:gain ratios than the control, respectively. At the end of the trial, final, empty and hot carcass weights and overall ADG of the 0.90 ad libitum RR group did not differ from control. Feeding performance values of the 0.80 ad libitum R group were the lowest among the treatments. The studied feed restriction regimens depressed the weights of empty stomach, tail fat, visceral fat, and subcutaneous fat; however, two weeks of realimentation were not enough to induce complete weight recovery in these tissues. The 0.90 ad libitum RR restriction routine can be adopted as a nutritional management practice for fattening Najdi lambs.

Impact of short compensatory growth periods on performance,carcass traits, fat deposition, and meat properties of Najdi lambs

“…Compensatory growth is a complex metabolic function; it may be influenced by genetic factors, the age of animals, severity and duration of restriction, diet quality, and duration of the realimentation (3). There are conflict results about feed consumption during the realimentation phase; some studies reported a significant increase in feed intake (4,5) while others found no significant differences (1,6,7).…”

Performance and ruminal and intestinal morphometry of Santa Inês sheep submitted to feed restriction and refeeding

“…The decreases in ADG and FE and, consequently, in final body weight were commonly reported in several studies (Homem Júnior et al 2007Abouheif et al 2013Abouheif et al , 2015, being related that negative impacts are directly related to the nutritional plan imposed, resulting in an inadequate intake of nutrients (Cui et al 2018), in which are necessary to sustain the rapid growth and development of animal. When feed intake is insufficient to cover their maintenance requirements, animals make use of body reserves, causing weight loss, and the magnitude of the reserve mobilization will depend on the severity and duration of the feed shortage (Pastén et al 2010).…”

“…The compensatory gain cannot be attributed to DMI, since there was no difference between the restricted and ad libitum groups in both weight groups, but possibly due to the better feed efficiency of the feed restricted lambs (Yambayamba et al 1996;Abouheif et al 2015;Ma et al 2017). These results are in agreement with those of Abouheif et al (2013) andHomem Júnior et al (2010), but different from those found by Greeff et al (1986) andHomem Júnior et al (2007), who reported that the rapid gain during refeeding was associated with increased feed intake, which did not occur in the present study.…”

“…There are conflicting results about daily weight gain after a period of feed restriction. Some authors (Homem Júnior et al 2007;Abouheif et al 2013Abouheif et al , 2015 reported a significant increase in daily gain, while others (Mahouachi and Atti 2005) reported no significant difference. For the total compensatory gain, the lambs with 20 kg of body weight subjected to 25 and 40% of feed restriction should have presented a daily weight gain of 273 and 334 g day −1 , respectively, in the refeeding period.…”

“…Sheep respond differently to refeeding when dietary restrictions are lifted. Compensatory gain was associated with higher feed intake (Kamalzadeh et al 1997), better feed conversion (Homem Júnior et al 2007;Shadnoush et al 2011), greater feed efficiency (Abouheif et al 2013), and greater weight gain (Abouheif et al 2015), and mainly, with the best nutrient utilization due to the modifications in the size and morphology of the internal organs (Addah et al 2017).…”