Effects of time-based feed restriction on morbidity, mortality, performance and meat quality of growing rabbits housed in collective systems

Abstract

In rabbit farms, quantitative feed restriction in the post-weaning period is widely used with the aim of reducing the impact of digestive diseases, whereas less information is available about feed restriction strategies based on the reduction of access time to feeders in different housing systems. This study compared morbidity, mortality, growth performance, carcass characteristics and meat quality of 368 crossbred rabbits fed ad libitum (L) or subjected to a time-based feed restriction programme (R) and housed from 31 to 73 days of age in cages or pens with different dimensions and group sizes, that is, eight conventional cages (0.33 m2, six rabbits/cage), eight small open-top pens (0.50 m2, eight rabbits/pen), eight medium open-top pens (1.00 m2, 16 rabbits/pen) and four large open-top pens (2.00 m2, 32 rabbits/pen). Feed restriction was attained by progressively reducing the access time to feeders in the 1st week from 14 to 8 h/day, maintaining 8 h in the 2nd week and then by increasing access time by 1 h/day during the 3rd and 4th week up to 24 h/day. In the first 2 weeks, R rabbits showed a lower (P ≤ 0.001) daily weight gain, feed intake and feed conversion as compared with L rabbits. During the 3rd and 4th weeks, R rabbits exhibited a greater daily weight gain and better feed conversion (P ≤ 0.001). In the last 2 weeks of trial, daily weight gain tended (P = 0.06) to be greater in the R than L rabbits. In the whole trial, R rabbits manifested a lower daily weight gain, feed intake and feed conversion, as well as lower final live weight and the carcass dressing percentage at slaughter (0.05 ≤ P ≤ 0.01). During feed restriction, R rabbits did not show digestive problems, which, however, appeared in the following 2 weeks of refeeding. Thus, R rabbits had a higher health risk index in the whole trial as compared with L rabbits (P ≤ 0.05). The housing system did not affect growth performance, characteristics at slaughter, and carcass and meat quality. Mortality tended to increase with group size (P = 0.06). In conclusion, the time-based feed restriction significantly improved feed efficiency of growing rabbits housed collectively but had somewhat negative effects on characteristics at slaughter and on morbidity and mortality rate.

Impact of pre-breeding feeding practices on rabbit mammary gland development at mid-pregnancy

“…For fattening rabbits, feed restriction during rearing period allowed uniformity in body weight and decreased neonatal mortality (Rommers et al2001). While a moderate feeding restriction may improve some sperm morphologic characteristics, as well as fertility in male rabbits (Pascual et al 2016), it seems that restriction strategies have shown less beneficial effects and even more for rabbit does (Birolo et al 2020). Restricting feeding during different stages of pregnancy, even if it does not strongly affect growth of young rabbits, may delay placental growth, decrease the offspring survival and birth weight (Rommers et al 2004; Matsuoka et al 2012; Manal, Tony, and Ezzo 2010).…”

“…For fattening rabbits, feed restriction during rearing period allowed uniformity in body weight and decreased neonatal mortality (Rommers et al, 2001). While a moderate feeding restriction may improve some sperm morphologic characteristics, as well as fertility in male rabbits (Pascual et al, 2016), it seems that restriction strategies have shown less beneficial effects and even more for rabbit does (Birolo et al, 2020).…”

A comparative study on the effect of quantitative feed restriction in males and females of broiler chickens, rabbits and nutrias. I. Performance and carcass composition

“…Gratta et al (2019) stated that late-restricted (from 27 to 37 days of age) chickens had a significantly lower carcass weight and breast proportion, while earlyrestricted (from 13 to 23 days of age) chickens had an intermediate carcass weight and breast percentage compared to those of ad libitum fed chickens. In rabbits, Birolo et al (2016;2020a), Alabiso et al (2017), and Chodova et al (2019) did not observe a significant effect of FR on carcass composition, while Gidenne et al (2012), Chodova et al (2016) and Birolo et al (2020b) observed lower DOP in restricted rabbits. In our recent experiment with nutrias, FR increased the hind part and perirenal fat percentage (Tumova et al 2021a).…”

Nutritional strategies to improve carcass yield and carcass composition in fattening rabbits

“…In this trial was not observed any difference among groups, that may have been because the mortality was moderate (12.8% on average). In fact, in other studies the feed restriction did not reduce the mortality rate below 9-17% when that of control group was between 15 and 23% (Gidenne et al, 2009c;Knudsen et al, 2014;, or even tended to increase it (Birolo et al, 2020), although other authors found very positive effects (Birolo et al, 2016;Romero et al, 2010), even compared to a medicated feed (Alabiso et al, 2017). There is no clear explanation for these differences among studies, and a combination of factors like the farm health status, diet, method of feed restriction employed, or type of housing might be behind them.…”

“…However, other authors (Gidenne et al, 2012;Knudsen et al, 2017;Birolo et al, 2020) reported an impairment of the carcass yield. Normally, the impairment is related to higher weight of the full tract associated with the development of internal organ such as small and large intestines, caecum and the liver during the restriction period and refeeding (Tumová et al, 2016).…”