Carcass and meat quality traits of rabbits under heat stress

Abstract

Rabbits are very sensitive to heat stress because they have difficulty eliminating excess body heat. The objective of the current study was to evaluate the effects of heat stress on slaughter weight, dressing percentage and carcass and meat quality traits of rabbits from two genetic groups. Ninety-six weaned rabbits were used: half were from the Botucatu genetic group and half were crossbreds between New Zealand White sires and Botucatu does. They were assigned to a completely randomized design in a 2 3 3 factorial arrangement (two genetic groups and three ambient temperatures: 188C, 258C and 308C) and kept under controlled conditions in three environmental chambers from 5 to 10 weeks of age. Slaughter took place at 10 weeks, on 2 consecutive days. Meat quality measurements were made in the longissimus muscle. Actual average ambient temperature and relative humidity in the three chambers were 18.48C and 63.9%, 24.48C and 80.2% and 29.68C and 75.9%, respectively. Purebred rabbits were heavier at slaughter and had heavier commercial and reference carcasses than crossbreds at 308C; however, no differences between genetic groups for these traits were found at lower temperatures. No genetic group 3 ambient temperature interaction was detected for any other carcass or meat quality traits. The percentages of distal parts of legs, skin and carcass forepart were higher in crossbred rabbits, indicating a lower degree of maturity at slaughter in this group. The percentage of thoracic viscera was higher in the purebreds. Lightness of the longissimus muscle was higher in the purebreds, whereas redness was higher in the crossbreds. Slaughter, commercial and reference carcass weights and the percentages of thoracic viscera, liver and kidneys were negatively related with ambient temperature. Commercial and reference carcass yields, and the percentage of distal parts of legs, on the other hand, had a positive linear relationship with ambient temperature. Meat redness and yellowness diminished as ambient temperature increased, whereas cooking loss was linearly elevated with ambient temperature. Meat color traits revealed paler meat in the purebreds, but no differences in instrumental texture properties and water-holding capacity between genetic groups. Purebred rabbits were less susceptible to heat stress than the crossbreds. Heat stress resulted in lower slaughter and carcass weights and proportional reductions of organ weights, which contributed to a higher carcass yield. Moreover, it exerted a small, but negative, effect on meat quality traits.

Effect of gestational and lactational exposure to heat stress on performance in rabbits

“…Nevertheless, HS applied during lactation resulted in decreased growth and final liveweight with the consequent impact on production, which was consistent with earlier studies in this field (Renaudeau et al, 2012;Baumgard and Rhoads, 2013;Zeferino et al, 2013). Studies published to date have considered that rabbit growth is mainly dependent on two factors, birth weight and litter size, as the kit spends half of its life with the mother (gestation and lactation, Poigner et al, 2000).…”

“…In rabbit, it has been established that growth performance of kits up to 21 d of age mainly depends on their mother's milk production and composition (Maertens et al, 2006), especially during the 3 rd wk of lactation (Szendrö et al, 1998). Moreover, HS also decreased feed intake and depressed the performance of growing rabbits (Marai et al, 2002;Zeferino et al, 2011Zeferino et al, , 2013. Consequently, HS depressed slaughter weight at a fixed market age as well as the commercial and reference carcass weights (Zeferino et al, 2011).…”

Meat physical quality and muscle fibre properties of rabbit meat as affected by the sire breed, season, parity order and gender in an organic production system

“…As for the season effect, the literature described mainly the negative effect of high temperatures on live performance and on carcass and meat quality of hybrid rabbits reared under intensive conditions (Chiericato et al, 1993;Marai et al, 2002;Zeferino et al, 2011Zeferino et al, , 2013, whereas information on crosses of coloured breeds extensively farmed D'Agata et al, 2009), or on rabbits reared under organic conditions are still scarce (Pla, 2008;Paci, 2013, 2014;Paci et al, 2014).…”

A balanced perspective on animal welfare for improved meat and meat products

“…The mortality of animals, especially chickens and pigs, increases because of heat stress and long distance transportation without rest (Von Keyserlingk et al, 2009;Melesse et al, 2011). In addition, heat stress affects the metabolism and performance of animals because they become too sensitive to heat, especially if there is no air circulation during transportation (Dalla Costa et al, 2007;Koknaroglu & Akunal, 2013;Zeferino et al, 2013). Stress is a physiological disturbance that is linked to mental states associated with threatening or harmful and painful situations (Von Holleben et al, 2010).…”

“…DFD beef develops in cattle (pH >5.9), while in poultry and pork, a rapid fall of pH (pH <5.3) results in pale soft and exudative (PSE) (Young et al, 2004;Gregory, 2010;Gajana et al, 2013). Elevated environmental temperatures affect poultry performance, physiology and their immune system (Star et al, 2009;Melesse et al, 2011), and reduced feed intake, slaughter weight, myoglobin content and meat sensory properties in rabbits (Zeferino et al, 2013), PSE pork and increased bruising score are associated with cold ambient temperatures (Dalla Costa et al, 2007). There are few reports on the effect of heat stress in sheep and cattle, although Gregory (2010) stated that occurrences of cattle that were dead on arrival and incidences of DFD beef had been observed.…”