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The objective of this study was to investigate the effect of dietary supplementation with fish oil on growth performance (during all fatening period), carcass characteristics and fatty acid (FA) profile of muscle and fat tissues (at slaughter), as well as cecal fermentation and ileal mucosa morphology of growing rabbits (at 30, 45, and 60 d of age). Two isonitrogenous and isoenergetic diets, only differing in their fat source, were formulated and provided each to 24 does (12 per diet) and their offspring during pregnancy and lactation. The control diet contained 4.59 g of n-3 per 100 g of total FA, and the enriched diet contained 14.9 g of n-3 per 100 g of total FA. From weaning (30 d of age) to slaughter (60 d), the litters (12 per diet; 8 kits each) continued fed the corresponding experimental diet. There were no differences (P > 0.05) between groups in ADFI, ADG and G:F ratio during the growing period. At slaughter, BW, full gastrointestinal tract weight, carcass yield, meat color and pH, drip loss percentage, content of scapular fat and tissue composition of the left hind leg were similar between groups (P > 0.05), but perirenal fat was lower (P = 0.020) and skin weight and abdominal fat tended to be lower (P = 0.055 and P = 0.063, respectively) in enriched rabbits than in control ones. Total PUFA content in both LM and perirenal fat was greater (P = 0.021 and < 0.001, respectively) in enriched rabbits, that also showed lower n-6/n-3 ratios in LM (1.61 vs. 5.80; P < 0.001) and perirenal fat (4.71 vs. 12.0; P < 0.001) than those fed the control diet. Cecal concentrations of total VFA were greater (P < 0.001) in enriched than in control group at 30, 45 and 60 d of age, but diet did not affect (P≥ 0.332) VFA profile, with the exception of a lower (P = 0.013) proportion of minor VFA (sum of isobutyrate, isovalerate, and valerate) in control group. Diet did not affect (P > 0.255) either pH and NH3-N concentrations in the cecum or ileal morphology (crypt depth and villi length). The results showed that dietary fish oil supplementation enhanced beneficial long-chain n-3 FA and decreased n-6/n-3 ratio in rabbit meat and fat, being healthier for human consumption, without having negative effects on growth performance, cecal fermentation, and ileal morphology or carcass characteristics. [ABSTRACT FROM AUTHOR]

The aim of this work was to study the effects of the genotype of the dam, the embryo, or their interactions on prenatal growth by performing doublereciprocal embryo transfers between two lines of rabbits divergently selected for uterine capacity. Females from high (n = 53) and low (n = 48) lines were slaughtered at 72 h of gestation, and recovered embryos were transferred to the oviducts of recipient does from the high (n = 23) and low (n = 19) lines. Each recipient doe received eight embryos from the high line into one oviduct and eight embryos from the low line into the other. Recipient does were slaughtered on d 28 of gestation. The percentages of live fetuses at 28 d of gestation were 89.2 and 74% for high and low recipient lines, respectively. Length and weight of the empty uterine horn and weight of the full uterine horn were not affected by either the recipient or by donor line. Fetal weight was affected by the recipient line but not by the donor line. Fetuses gestated in high recipient does were 7% heavier (P < 0.10) than those in the low recipient does. There was a donor and a donor x recipient interaction effect on fetal placental weight. Fetal placental weight was heavier (7%, P < 0.01) for embryos from the low line. Embryos from the high line gestated in lowline uteri showed a lower fetal placenta weight than did low-line embryos gestated in high-line uteri and low-line uteri (P < 0.05). Linear regression coefficients of fetal weight at term on fetal placental weights differed (P < 0.05) for the high and low donors (4.33 ± 0.28 and 3.41 ± 0.29 respectively). A significant effect of the donor genotype on individual placental length was observed (P < 0.05), which might have resulted from a smaller individual placental length of low-line embryos gestated high-line uteri (P < 0.10). Neither donor nor recipient lines affected maternal placental weight or available space for fetuses. Fetuses and their fetal placentae were heavier when receiving more than four blood vessels than when receiving less than three blood vessels (13 and 17% respectively, P < 0.05). Neither recipient nor donor genotype affected the number of blood vessels arriving at each live fetus. Thus, fetal weight depends on the maternal genotype, whereas fetal placental weight depends on the embryo genotype in these two lines of rabbits divergently selected for uterine capacity. [ABSTRACT FROM AUTHOR]

The aim of this work was to determine whether prenatal survival depends on the genotype of the mother or of the embryo and to identify the critical periods for prenatal mortality in two lines of rabbits divergently selected by high (H) and low (L) uterine capacity. Does from H (n = 124) and L (n = 115) lines were slaughtered at 72 h of gestation. Embryos recovered at 72 h of gestation were transferred to the oviducts of recipient does from the H (n = 23) and L (n = 19) lines. Each recipient does received eight embryos from the H line into one oviduct and eight embryos from the L line into the other. Recipient does were slaughtered on d 28 of gestation. No differences were found between lines in the embryo recovery either in ovulation rate (OR) or in fertilization rate of ova recovered. Recovery rate was higher for the H line (0.80 vs. 0.72, P < 0.01). The number of embryos recovered, fitting ovulation rate as a covariate, was also higher for the H line (9.74 vs. 8.78, P < 0.05). The H line showed a more advanced embryonic stage of development, having a higher percentage of blastocysts (PB) and a lower percentage of compact morulae (PCM) (38% vs. 20%, P < 0.001 for PB, and 51% vs. 64%, P < 0.01 for PCM). The percentage of early morulae was low and similar in both lines. Neither donor nor recipient lines affected embryonic survival from 72 h to 7 d of gestation. Fetal survival was affected by the recipient line (P < 0.05). An interaction between donor and recipient was found. Embryos from the H donor line had a better fetal survival rate than embryos from the L donor line (P < 0.05) in H recipient females. Within L recipient females, embryos from H and L donor lines showed similar fetal survival. Fetal survival was divided into early (from d 7 to 17 of gestation) and late (from d 17 to 28 of gestation). The high recipient line showed a higher early fetal survival than the L recipient line (P < 0.05). The same effect was observed for late fetal survival, but the difference between H and L recipient lines was lower (P < 0.10). Thus, fetal survival depends mainly on the maternal genotype, and the embryo genotype only affects fetal survival when embryo transfer is performed to a favorable maternal environment. Selection for uterine capacity in rabbits leads to modification of early embryonic survival and of early and late fetal survival, but differences are higher for early than for late fetal survival. [ABSTRACT FROM AUTHOR]

Interest in low-fat diets coupled with attention for novel and locally-produced foods has led to a resurgence in rabbit meat consumption in the United States. Psyllium seed husks (PSH) from the Plantago ovata plant have been touted as a livestock nutritional enhancement designed to clean digestive tracts, improve performance and feed efficiency, and lower production costs; however, PSH has not been fully investigated in rabbit diets. Therefore, intact male and female New Zealand fryers (n = 44) were used to examine effects of diets with PSH or without (C) on carcass composition, fatty acid profile, and cholesterol of rabbits. Rabbit fryers (2.3 ± 0.54 kg BW) were sourced from 2 producers, and transported from southwest Missouri to the University of Arkansas abattoir, where they were humanely harvested. After harvest, carcass measurements were collected and LM samples were obtained for fatty acid analysis and cholesterol determination. Rabbits fed PSH had greater (P < 0.01) final B W, HCW, cold CW, and DP than rabbits fed C. Even though LM color and cooking losses did not differ (P ≥ 0.34) between treatments, LM from PSH-fed rabbits had greater (P < 0.01) shear force values than that from C-fed rabbits. Cholesterol content tended to be greater (P ≤ 0.07) in the LM of C than PSH rabbits. Among the various SFA, mg of C 10:0 was higher (P ≤ 0.01) in the LM of C-fed rabbits, whereas, LM concentrations of C14:0 was greater (P ≤ 0.04) in PSH-fed rabbits. All other SFA examined did not differ (P ≥ 0.26) between treatments. For MUFA, only C18:1t was found to be greater (P ≤ 0.03) in PSH-fed than C-fed rabbits; all other MUFA were similar (P ≥ 0.26) between treatments. Polyunsaturated fatty acids, C20:4n-6, C22:5, and C22:6 were greater (P ≤ 0.03) in PSH than C rabbits. Fatty acid C20:2 tended (P ≤ 0.07) to be higher in C vs. PSH. All other PUFA were similar (P ≥ 0.12) between dietary treatments. Total mg of FA found in LM of PSH- and C-fed rabbits did not differ (P ≥ 0.65). Weights and dressing percentages of rabbit fryers fed psyllium seed husks were improved relative to control rabbits sourced and harvested at the same time; however, shear force values were lower in control rabbits in this trial. Cholesterol tended to be lower and various differences were observed in the fatty acid profle of rabbits fed psyllium seed husks. [ABSTRACT FROM AUTHOR]