D. Chodová

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).

Effect of light colour on egg production and egg contamination

The objective of this study was to compare the performance of laying hens, quality of air in poul- try house, and microbial contamination of eggshell in laying hens kept under blue, green, red, and yellow light colour in enriched cages. The daily photoperiod consisted of 15 h light, light intensity of 10 lx at bird head level. The laying performance characteristics (hen-day egg production, mortality, and egg weight) were not affected by light colour. Similarly, microbial contamination of the air was not significantly different related to the light colour. There were significant interactions in eggshell contamination between the position of the cage floor and light colour in Escherichia coli ( P ≤ 0.042) and Enterococcus ( P ≤ 0.019). The highest number of Escherichia coli was detected in eggs from hens housed on the middle floor given yellow light (6.06 log colony forming units (cfu)/eggshell) and the lowest values (3.30 log cfu/eggshell) on the upper floor also under yellow light colour. Similar results were observed in Enterococcus, where the highest contamination was on the middle floor under yellow light colour (5.26 log cfu/eggshell), while the lowest contamination (2.45 log cfu/eggshell) was found on the upper floor under blue colour. The results of our study indicate that the light colour has a minor effect on microbial contamination but the significant influence was in the floor position. The highest microbial egg contamination was found on eggs from the middle floor.

The effect of one-week intensive feed restriction and age on the carcass composition and meat quality of growing rabbits

The effect of one-week intensive feed restriction on the carcass characteristics, meat tenderness, cooking loss, and muscle fibre characteristics of growing rabbits was evaluated. Weaned rabbits (35 days) were divided into three groups: rabbits fed ad libitum (ADL), rabbits fed 50 g (R50), and rabbits fed 65 g (R65) of feed per animal per day in days 42-49 of age. Dressing out percentage was lower (-1.3% and -2.3% for R50 and R65, respectively) in restricted rabbits (P ≤ 0.001) but increased with age (P ≤ 0.001). Cooking loss signifi- cantly increased in restricted rabbits. A significant interaction between feeding regime and age was observed in the number of type αR muscle fibres, the highest number (P ≤ 0.05) was observed in the ADL rabbits (114.5) at 49 days, and the lowest was found in the R50 group at 70 days of age (25.0). Feed restriction increased the percentage of αW glycolytic fibres (P ≤ 0.01). A significant negative correlation was found between cooking loss and the cross sectional area of αW fibres (-0.486) and αR (-0.325). It could be concluded that one-week intensive feed restriction did not have a negative effect on meat tenderness and cooking loss, despite the fact that it affected muscle fibre type distribution.

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.

Feed Restriction and Muscle Fibre Characteristics of Pectoralis Major in Broiler Chickens

Abstract The aim of the study was to evaluate the effect of one-week quantitative feed restriction (in days 8-14 of age) on histological characteristics of musculus pectoralis major in broiler chickens during the fattening period. Cockerels of Ross 308 (1215 chicken) were divided into 3 groups: ad libitum fed (AL; 3 × 135), restricted 80% of AL (R80; 3 × 135), and with limited feed intake 65% of AL (R65; 3 × 135). Eight cockerels per group were slaughtered in weekly intervals from day 14 of age till the end of experiment at 35 days to determine changes in the muscle fibre characteristics. The number of muscle fibres in pectoralis major decreased (P ≤ 0.001) with increasing age. Fibre cross sectional area was s ignificantly (P ≤ 0.027) affected by the interaction of group and age. At the end of feed restriction at 14 days all groups had similar fibre area (519-539 μm2), the differences between groups were observed at 35 days of age with the largest fibre area in R65 chickens (2296 μm2), while R80 did not differ from AL (1728 μm2 and 1667 μm2). There was no effect of feeding regime on giant muscle fibre incidence.

Effects of subclinical Eimeria tenella infection on Pectoralis major muscle in broiler chickens

Abstract The aim of this study was to evaluate changes in the histological characteristics of the pectoralis major (PM) muscle in chickens as well as histological changes in the caecum after a low dose of Eimeria tenella (E. tenella). The chickens were inoculated orally with 5 × 102 E. tenella oocysts (Gr1) and 1 × 103 E. tenella oocysts (Gr2) at 16 days of age. Six chickens from each group were sacrificed for post mortem examination at 9 days post-infection (pi) and 16 days pi. Chicken growth was not affected by infection. On the 9th day of infection, caecal villus height was significantly greater in the non-infected control group. However, infected chickens from group Gr1 sacrificed seven days later had an even greater caecal villus height than those of the control (p =.001). Both infected groups had higher PM weights at 16 days pi than did the control group (p = .001). The fibre cross-sectional area was smaller in Gr2 at 9 days pi; however, this parameter was larger in these chickens at 16 days pi. The pH value of PM of group Gr2 was significantly higher than that of the control group or group Gr1 at 16 days pi (p = .020).