Linda Uhlířová

The effect of 1-week feed restriction on performance, digestibility of nutrients and digestive system development in the growing rabbit.

A 3 to 4 week feed restriction of about 20% to 25% of the free intake is widely applied in rabbit breeding systems to reduce post-weaning digestive disorders. However, a short intensive feed restriction is described in few studies and can be beneficial for growing rabbits due to a longer re-alimentation period. The aim of this study was to evaluate the effect of ad libitum (AL) and two restriction levels of feeding (50 and 65 g/rabbit per day) applied for 1 week on performance, gastrointestinal morphology and physiological parameters during the restriction and during the re-alimentation period. Rabbits were divided into three experimental groups: AL rabbits were fed AL, R1 rabbits were restricted from 42 to 49 days of age and received 50 g daily (29% of AL) and R2 rabbits were restricted at the same age and were fed 65 g of feed daily (37% of AL). In the 1(st) week after weaning and in the weeks after restriction, all the groups were fed AL. During the restriction period, daily weight gain (DWG) in R1 significantly dropped to 11% (experiment 1) and 5% (experiment 2) compared with rabbits in the AL group, although they were fed 29% of AL, whereas in the R2 group it decreased to 20% (experiment 1) and 10% (experiment 2). In the week following feed restriction, DWG in the restricted groups increased (P<0.001) to 166% and 148% in R1 and to 128% and 145% in R2. Restricted rabbits in both the experiments reached up to 90% to 93% of the final live weight (70 days) of the AL group. Over the entire experimental period, feed restriction significantly decreased feed intake to 85% to 88% of the AL group; however, the feed conversion ratio was lower (P<0.05) only in experiment 1 (-6% in R1 and -4% in R2). Digestibilities of CP and fat were not significantly higher during the restriction period and during the 1(st) week of re-alimentation compared with the AL group. Significant interactions between feeding regime and age revealed the shortest large intestine in the AL group at 49 days of age and the longest at 70 days in the AL and R1 groups. Small intestinal villi were significantly higher and the crypts were significantly deeper in the restricted groups. It could be concluded that short intensive feed restriction increased digestible area in the small and large intestines, including the height of villi and depth of crypts, which might be involved in the compensatory growth and defence mechanism.

Carcass composition and meat quality of Czech genetic resources of nutrias (Myocastor coypus).

The effects of sex and colour type on carcass composition, nutrients content, and muscle fibre characteristics of hind leg meat of nutrias raised under intensive conditions were the focus of this study. Thirtysix eight-month-old nutrias of both sexes with three colour types (Standard nutria, ST; Moravian Silver, MS; and Prestice Multicolour, PM) were studied. Live weight was affected by colour type (P < 0.05) and sex (P < 0.001); however, no effects of these variables were found for the dressing out percentage. Crude protein content was significantly higher in males than in females, whereas crude fat content was higher in females. A significant interaction between colour type and sex was found for hydroxyproline and ash contents. Fatty acids were affected primarily by the sex of nutrias. No effect of colour type on the distribution of muscle fibres in the Biceps femoris muscle was found. However, females had fewer βR (P < 0.05) and more αR fibres (P < 0.001) than males.

Age-related changes in the carcass yield and meat quality of male and female nutrias (Myocastor coypus) under intensive production system

The age at which final nutria weight is achieved varies in literature between six and 14months. The aim of this study was to evaluate the growth, carcass composition and meat quality of male and female nutrias between the ages of six and eight months in intensive production system. Sexual dimorphism in growth was observed from three months of age, and in females, growth considerably decreased after six months of age. The dressing-out percentage and the meat color were not affected by the age or sex of nutrias. Dry matter, ether extract and energetic values were significantly higher in females and in older nutrias. The decreasing frequency of type IIA fibers in older nutrias was presumably associated with a conversion of type IIA fibers to type IIB fibers. Nutrias under intensive production system can be slaughtered at six months of age when they reach a high carcass yield and meat quality.

Age related changes in laying pattern and egg weight of different laying hen genotypes

The aim of the study was to evaluate changes in laying patterns depending on the age of different genotypes of laying hens. In the experiment, six genotypes were evaluated (brown-egg hens Bovans Brown, Bovans Sperwer and Isa Sussex, white-egg hens Dekalb White, and laying hens with tinted shells Moravia Barred and Moravia BSL) in three periods during the laying cycle (the onset of lay between 20 and 26 weeks of age, the middle from 36 to 42 weeks of age and the end of lay between 64 and 70 weeks of age). A significant interaction between genotype and age was apparent in mean sequence length (P<0.001), length of the prime sequence (P<0.001), mean number of sequences (P<0.001) and mean time of oviposition (P˂0.001). The longest lag during the course of the experiment was with Moravia BSL, which was more than 3h; the shortest lag was observed in Bovans Brown, which was less than 1h. The mean time of oviposition was also affected by genotype (P˂0.001). Bovans Brown laid their eggs approximately 3.5h after the lights came on, whereas Moravia BSL laid their eggs almost 6h after the lights came on. Egg weight increased with age (P˂0.001), and the smallest differences in egg weight were with ISA Sussex (5g), whereas the biggest differences were with Moravia BSL (10g).

Relationship between muscle fibre characteristics and meat sensory properties in three nutria (Myocastor coypus) colour types.

The study determined the muscle fibre characteristics and sensory properties of the longissimus lumborum muscle (LL) of eight-month-old nutrias of three colour types and the correlations between meat histochemical measurements and eating quality. The following nutria colour types were used in the experiment: Standard (ST), Moravian Silver (MS), and Prestice Multicolour (PM). The nutria colour type significantly (P < 0.001) affected the number of type IIB fibres with the lowest number in ST (108 per mm2). The proportion of type I fibres varied between 10.6 and 14.2%; type IIA fibres varied between 6.1 and 7.8%; and type IIB fibres varied between 78.2 and 83.4% and it was not affected by colour type. The cross-sectional area (CSA) was 2.565–2.841 μm2 in type I, 2.867–3.010 μm2 in type IIA, and 4.698–5.517 μm2 in type IIB fibres. The CSA of type IIB fibres (P < 0.001) was the largest in ST. The sensory trait of tenderness (P < 0.05) was the lowest in MS. Correlations between the proportion of fibres and sensory traits were not observed. The CSA of type I fibres correlated with flavour (0.19) and the CSA of type IIB fibres with tenderness (0.10).

White lupin bran and its effects on the growth performance, carcass characteristics and digestibility of nutrients in fattening rabbits

The purpose of the present study was to evaluate the effects of including white lupin bran (WLB) in a fattening rabbit diet on growth, carcass traits and nutrient digestibility. The C diet (control) based on alfalfa meal, whereas the WLB 5 and WLB 15 diets were based on white lupin bran (crude protein 152 g/kg, neutral detergent fibre 524 g/kg as-fed basis). The WLB 5 diet contained 50 g of white lupin bran/kg instead of 50 g of alfalfa meal/kg, whereas the WLB 15 diet contained 150 g of white lupin bran/kg, 5 g of soybean meal/kg and 10 g of sugar beet pulp/kg instead of 165 g of alfalfa meal/kg. The diets had similar digestible protein/digestible energy ratios. A total of 150 Hyplus rabbits between the ages of 30 to 73 d were randomly allocated into one of 3 groups and fed one of the 3 experimental diets. Additionally, another 30 Hyplus rabbits (10 per dietary treatment) at the age of 30 d were selected to determine coefficients of total tract apparent digestibility (CTTAD) of diets between 63 and 67 d of age. The dietary treatments did not affect the final live weight of rabbits (mean=2969 g). There was a higher feed intake (+30 g/d; P<0.001) in both groups of rabbits fed the WLB 5 and WLB 15 diets compared to rabbits fed the C diet, which led to impaired feed conversion ratios (P<0.001). Sanitary risk index was not affected by dietary treatment. The rabbits fed the WLB 15 diet exhibited a higher drip loss percentage (+0.65%; P<0.001) than the rabbits fed the other diets, as well as a lower dressing-out percentage (by 1.6%; P=0.024). The CTTAD of the lignocellulose fraction (acid detergent fibre) was significantly higher in rabbits fed the WLB 5 and WLB 15 diets than in those fed the C diet. White lupin bran may be used as a dietary fibrous by-product without significant impairment of the nutritive value of the diet. This lupin by-product can be included in diets for fattening rabbits up to 15% as a partial replacement of alfalfa meal.

Effect of dietary dehulled white lupine seed supplementation on the growth, carcass traits and chemical, physical and sensory meat quality parameters of growing-fattening rabbits

This work aimed to extend our current knowledge by obtaining novel information regarding the effect of the dietary inclusion of dehulled white lupine seeds (DWL) on the physical characteristics and sensory qualities of rabbit meat, as well as growth and carcass traits. The DWL diet was compared with a soybean meal-based diet. Feeding the DWL diet to rabbits led to lower Warner-Bratzler shear force values measured in grilled meat samples (Longissimus lumborum muscle) across fibers and this finding was confirmed in the sensory evaluation of texture in terms of higher tenderness and fibrosity of meat samples. No differences were detected by panelists in terms of intensity of aroma, the presence of a flavor typical for cooked meat, or the presence of a flavor typical for rabbit meat. Additionally, saturation and thrombogenic indexes from hind leg meat of rabbits fed the DWL diet were reduced. There was a better feed conversion ratio in rabbits fed the DWL diet.

Fatty acid composition of goose meat depending on genotype and sex

Objective The aim of this study was to compare male and female geese of two contrasting genotypes in terms of fatty acid composition, indexes related to human health, lipid metabolism and oxidative stability of the meat. Methods The experiment was carried out on total of 120 geese of two different genotypes; the native breed Czech goose (CG) and commercial hybrid Novohradska goose (NG). One-d-old goslings were divided into 4 groups according to genotype and sex, and 8 birds from each group were slaughtered at 8 weeks of age. Results The effects of the interactions between genotype and sex were observed on growth performance and carcass traits. Final body weight (p<0.001), daily weight gain (p<0.001), daily feed intake (p<0.001), slaughter weight (p<0.001), and cold carcass weight (p<0.001) were highest in NG males and lowest in CG females. The meat fatty acid composition results showed effects of both genotype and sex on the total n-6 and the total polyunsaturated fatty acid (PUFA) content, as well as the PUFA n-6/PUFA n-3 ratio. Regarding genotype, the total n-6, the total PUFA content and the PUFA n-6/PUFA n-3 ratio were higher in CG, and higher values were found in females. In terms of the lipid metabolism, Δ5–Δ6 desaturase (p = 0.006) was higher in males. The meat oxidative stability results revealed an interaction between genotype, sex and storage time (p<0.001). The highest (13.85 mg/kg) malondialdehyde content was measured in the meat of CG females after 5 days of storage and was presumably related to a higher PUFA content. Conclusion NG had a relatively higher growth rate and meat oxidative stability, whereas the advantage of CG meat is its favourable fatty acid profile characterized by a higher PUFA content.

The effect of age, genotype and sex on carcass traits, meat quality and sensory attributes of geese

Objective The aim of this study was to compare carcass traits, meat quality and sensory attributes in two different genotypes of geese according to age and sex. Methods The experiment was carried out on 160 birds of two genotypes of geese: the Czech Goose (CG) breed and a Eskildsen Schwer (ES) hybrid. One-d-old goslings were divided into four groups according to genotype and sex. Two dates for slaughtering (at 8 and 16 wk of age of goslings) were undertaken. Results The slaughter weight, cold carcass weight and dressing percentage were affected by all the studied factors, and significant interactions between age, genotype and sex were detected in the slaughter weight (p<0.001) and cold carcass weight (p = 0.004). The pH was not affected by any of studied factors, whereas in terms of meat colour parameters there were observed significant effects of age on L* and b* value and a significant effect of sex on a* value. The meat fat content was higher (p = 0.002) in ES. Higher score for overall acceptance of goose meat was recorded for ES at both ages compared to CG. Conclusion ES had higher dressing percentage and better sensory attributes, whereas CG exceled in the favourable nutritional value of the meat.