Digestive efficiency in rabbit does according to environment and genetic type

The general aim of this research was to study the effect of high ambient temperature on the performance of does during lactation, specifically the following factors: average daily feed (ADFI) and water (ADWI) intakes, daily milk yield (DMY); milk composition: dry matter (DM), CP and gross energy (GE); doe BW (DW); individual kit weaning weight (IWW) and litter survival rate during lactation (SR). The study was undertaken comparing the performance of two groups of contemporary does reared under the same management, feeding regime and environmental conditions, except the environmental temperature and humidity. A total of 80 females were randomly allocated, at 60 days of age, into two identical and continuous rooms. In one room, the temperature was maintained permanently within the thermo-neutral zone (between 18°C to 22°C); thus, environmental conditions in this room were considered as comfort conditions. In the second room, the environmental temperature pattern simulated the daily temperature cycles that were characteristic of the summer in Mediterranean countries (24°C at 0800 h, increasing up to 29°C until 1100 h; maintenance at 29°C to 31°C for 4 h and decreasing to about 24°C to 26°C around 1700 h until 0800 h of the following day), which were considered as thermal stress conditions. Females followed a semi-intensive reproductive rhythm, first artificial insemination at 4.5 months of age, with subsequent 42-day reproductive cycles. Traits were recorded from a total of 138 lactations. Does were controlled up to the 5th lactation. Data were analyzed using linear and linear mixed models. High ambient temperature led to a lower ADFI (−9.4%), DW (−6.2%) and IWW (−8%), but it did not affect ADWI. No significant difference was found either for DMY, milk composition (DM, CP and GE) and SR during the lactation period. Heat stress was moderate, and does were able to adapt to it behaviorally by decreasing feed intake (to reduce heat production), but also live weight, allowing them to preserve milk yield and composition for assuring litter survival. On the other hand, water consumption could not be the main animal mechanism to overcome heat stress.Keywords: food and water consumption, heat stress, milk yield, milk composition, rabbits ImplicationsAssessing the effect of heat on lactating doe performance is crucial before defining the best strategies regarding management and selection practices to alleviate the negative impact of this factor on animal welfare and production. This study evaluates lactation performance of two groups of does that were raised and reproduced either under circadian cycle of temperature emulating the Mediterranean summer or under constant comfort temperature conditions. We show that rabbit does were able to adapt to moderate heat stress by decreasing feed intake, and thus live weight, but preserving milk yield and composition to ensure litter survival.

Section: Discussionsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Lactating performance, water and feed consumption of rabbit does reared under a Mediterranean summer circadian cycle of temperature v. comfort temperature conditions

Bakr

Tusell

Rafel

et al. 2015

“…Finally, the nutritional challenging environment (NF) was created by combining normal room temperatures (N) with a low-energy fibrous diet (F), formulated to achieve 9.1 MJ DE/kg DM, 104 g digestible protein/kg DM and 266 g ADF/kg DM, which is clearly below the recommendations for lactating rabbit does (de Blas and Mateos, 2010). Ingredients, chemical composition and apparent digestible coefficients of the experimental diets used in the different environments and the DE intake were calculated from digestibilities obtained in each environment, as described at Savietto et al (2012). Savietto, Cervera, Blas, Baselga, Larsen, Friggens and Pascual Therefore, the DE content of diets consumed by LP and V female rabbits were 12.67 and 12.43 at HC, 11.65 and 11.54 at NC, and 8.95 and 9.12 MJ DE/kg DM at NF, respectively.…”

Section: Environmentsmentioning

confidence: 99%

Environmental sensitivity differs between rabbit lines selected for reproductive intensity and longevity

Savietto

Cervera

Blas

et al. 2013

To better understand the mechanisms that allow some animals to sustain their productive effort in harsh environmental conditions, rabbit does from two selection lines (LP and V) were housed in normal (NC), nutritional (NF) or heat (HC) challenging environmental conditions from first to third partum. The LP line (n = 85) was founded on reproductive longevity criteria by selecting does from commercial farms that had a minimum of 25 partum with more than 7.5 kits born alive per parity. Line V (n = 79) was constituted from four specialised maternal lines into a composite synthetic line and then selected by litter size at weaning for 36 generations. Female rabbits in NC and NF environments were housed at normal room temperature (18°C to 24°C) and fed with control [11.6 MJ digestible energy (DE)/kg dry matter (DM)] or low-energy diets (9.1 MJ DE/kg DM). HC does were housed at high room temperatures (25°C to 35°C) and fed the control diet. Female rabbits in the HC and NF environments ingested 11.5% and 6% less DE than NC does, respectively ( P < 0.05). These differences between environments occurred in both lines, with the differences being higher for LP than for V does (+6%; P < 0.05). Milk yield responses followed those of energy intake also being higher for LP does (+21.3 g/day; P < 0.05). The environmental conditions did not affect the perirenal fat thickness (PFT), but a genotype by environment interaction was observed. In NC and HC, the PFT was higher for line V (+0.23 and +0.35 mm, respectively; P < 0.05) than for LP does, but this was not the case at NF (−0.01 mm). Moreover, the PFT evolution was different between them. In the NC environment, LP does used the accreted PFT in late lactation (−0.29 mm), whereas V does did not (−0.08 mm). Conversely, in the HC environment, LP does showed a flat PFT evolution in late lactation, whereas V does accumulated PFT. In the NF environment, LP and V does had a similar PFT evolution. There was also a litter size reduction for V does of −2.59 kits total born in HC and −1.78 kits total born in NF environments, whereas this was not observed for LP does. The results for LP does indicate a direct use of DE ingested for reproduction with little PFT change, whereas V does actively use the PFT reserves for reproduction.

“…Finally, an environmental restriction because of feed quality (NF) was produced by combining N housing with a low-energy fibrous diet (F: 9.1 MJ DE/kg DM, 104 g DP/kg DM and 266 g ADF/kg DM), following recommendations for lactating rabbit does (Nicodemus et al, 2010). Ingredients and chemical composition of the experimental diets are available online as a Supplementary Material (Supplementary Table S1) and the apparent digestible coefficients for each generation and environment are given by Savietto et al (2012), from a sample of animals used in the present study. As a reference, the calculated DE content of diets in N housing was 11.7 MJ DE/kg DM for diet C and 9.1 MJ DE/kg DM for diet F. In H housing, the DE content of diet C was 12.5 MJ DE/kg DM.…”

Section: Environmentsmentioning

confidence: 99%

Different resource allocation strategies result from selection for litter size at weaning in rabbit does

Savietto

Cervera

Ródenas

et al. 2014

This study examined the effect of long-term selection of a maternal rabbit line, solely for a reproductive criterion, on the ability of female rabbits to deal with constrained environmental conditions. Female rabbits from generations 16 and 36 (n = 72 and 79, respectively) of a line founded and selected to increase litter size at weaning were compared simultaneously. Female rabbits were subjected to normal (NC), nutritional (NF) or heat (HC) challenging conditions from 1st to 3rd parturition. Animals in NC and NF were housed at normal room temperatures (18°C to 25°C) and respectively fed with control (11.6 MJ digestible energy (DE)/kg dry matter (DM), 126 g digestible protein (DP)/kg DM, and 168 g of ADF/kg DM) or low-energy fibrous diets (9.1 MJ DE/kg DM, 104 g DP/kg DM and 266 g ADF/kg DM), whereas those housed in HC were subjected to high room temperatures (25°C to 35°C) and the control diet. The litter size was lower for female rabbits housed in both NF and HC environments, but the extent and timing where this reduction took place differed between generations. In challenging conditions (NF and HC), the average reduction in the reproductive performance of female rabbits from generation 16, compared with NC, was −2.26 (P < 0.05) and −0.51 kits born alive at 2nd and 3rd parturition, respectively. However, under these challenging conditions, the reproductive performance of female rabbits from generation 36 was less affected at 2nd parturition (−1.25 kits born alive), but showed a greater reduction at the 3rd parturition (−3.53 kits born alive; P < 0.05) compared with NC. The results also showed differences between generations in digestible energy intake, milk yield and accretion, and use of body reserves throughout lactation in NC, HC and NF, which together indicate that there were different resource allocation strategies in the animals from the different generations. Selection to increase litter size at weaning led to increased reproductive robustness at the onset of an environmental constraint, but failure to sustain the reproductive liability when the challenge was maintained in the long term. This response could be directly related to the shortterm environmental fluctuations (less severe) that frequently occur in the environment where this line has been selected.