A 3-week feed restriction after weaning as an alternative to a medicated diet: effects on growth, health, carcass and meat traits of rabbits of two genotypes

Abstract

Feed restriction after weaning is widely used in meat rabbit farms to promote health and reduce mortality, but this practice impacts negatively on rabbit growth and slaughter performance. This study compared a 3-week post-weaning feed restriction with ad libitum medicated feeding, evaluating effects on feed intake, growth, health, carcass and meat quality of rabbits of two genotypes: Italian White pure breed and Hycole hybrid × Italian White crossbred. A total of 512 rabbits at 36 days of age, of both sexes and two genotypes, were divided into four homogeneous groups assigned, from 36 to 57 days of age, to different feeding programmes (FP): restricted non-medicated (R-N), ad libitum non-medicated (L-N), restricted medicated (R-M) and ad libitum medicated (L-M). The diets were medicated with oxytetracycline (1540 mg/kg) and colistin sulphate (240 mg/kg). The restriction, performed by giving 70, 80 and 90 g/day of feed for the 1st, 2nd and 3rd week, was followed by ad libitum feeding in the successive 5 weeks, up to slaughter at 92 days of age. Restricted feeds were ingested at a level of 64% of the feed intake recorded in the ad libitum fed rabbits; it was significantly associated, regardless of medication and rabbit genotype, with a lower feed intake (−22 to −24 g dry matter/day) during the entire experiment, compensatory growth and a lower feed conversion ratio in the ad libitum period, and a lower final live weight (−150 g) than ad libitum feeding (P < 0.001). During restriction, mortality was lower in the restricted rabbits (6.25%, 5.47% v. 12.5%, 14.8% for R-N, R-M, L-N and L-M; P < 0.05), whereas in the ad libitum period mortality did not differ among the groups (9.23%, 9.90%, 11.0% and 4.59% for R-N, R-M, L-N and L-M). Dressing out percentage was not affected by FP or genotype; heavier carcasses were produced by rabbits fed ad libitum (+100 g; P < 0.001) and crossbred rabbits (+122 g; P < 0.001). Restriction did not alter meat quality, except for a tendency towards a higher cooking loss and less fat; crossbred meat was higher in L* (+1.3; P < 0.01) and b* (+0.51; P < 0.05) colour indexes and tenderness (−0.14 kg/cm 2 ; P < 0.05) than pure breed meat. Under the conditions of this study, a 3-week restricted feeding after weaning resulted to be a suitable alternative, also for high growth potential genotypes, to the antibiotics to preserve rabbit health. The production of lighter carcasses could be compensated partly by the lower feed conversion ratio showed by restricted rabbits.

The effect of limited feed intake on carcase yield and meat quality in early weaned rabbits

“…In terms of meat quality characteristics, tenderness is the most important factor for consumers. Feed restriction did not affect the meat toughness and was consistent with Carrilho et al (2009), Alabiso et al (2016) and our previous results (Chodov a et al 2016). The cooking loss is one of the parameters by which the water holding capacity is expressed, and there was no effect of feeding regime on cooking loss, which corresponds with the observations of .…”

“…Our feeding regime did not affect the dressing out percentage, as was also observed by Tůmov a et al (2003,2006), Oliveira et al (2012) and Alabiso et al (2016). In contrast, the application of feed restriction at 35 days of age, one week after weaning, resulted in a lower dressing out percentage in restricted rabbits (Chodov a et al 2016).…”

“…During the realimentation period, when animals are again fed ad libitum, compensatory growth is observed, and its intensity is related to the intensity of feed restriction (Gidenne et al 2012). However, the average daily weight gain observed by most authors over the whole experimental period is lower in restricted rabbits weaned at 35 days of age than in rabbits fed ad libitum Oliveira et al 2012;Alabiso et al 2016;Tůmov a, Volek et al 2016). In the present study, feed intake was similar for restricted rabbits and those fed ad libitum, and this result agrees with those of Tůmov a et al (2003) and Romero et al (2010).…”

Growth, carcass and meat quality traits of two South African meat rabbit breeds

“…Overall, the live weights of both the South African NZW and Phendula rabbits compared well with those reported for various breeds, breed crosses and hybrid lines in recent literature (Pascual et al, 2015;Alabiso et al, 2017;Nasr et al, 2017;Belabbas et al, 2019). However, in the absence of standardized rearing and environmental conditions, the value of these comparisons is limited.…”

“…The greater live weights for female rabbits than males of both breeds at 11 weeks old resulted from the greater ADG of females towards the end of the growth period (Figure 1), These results differed from North et al (2018a), in which no sex effect on live weight was detected for NZW from the same genetic stock. Bernardini Battaglini et al (1995), Ortiz Hernández & Rubio Lozano (2001, Yalçin et al (2006) and Alabiso et al (2017) similarly reported no sex differences in live weight or SW for a variety of genetic types. However, whereas Blasco & Gomez (1993) found no sex differences in a line selected for growth rate, females from a line selected for litter size had significantly greater live weights than males from the same line.…”