Effect of different weaning age (21, 28 or 35 days) on production, growth and certain parameters of the digestive tract in rabbits

The effect of different weaning ages, that is, 21 (G21), 28 (G28) or 35 (G35) days, on growth and certain parameters of the digestive tract was examined in rabbits to assess the risk of early weaning attributable to the less-developed digestive system. On days 35 and 42, G35 rabbits had 10% to 14% and 10% higher BW, respectively ( P,0.05), than those weaned at days 21 and 28. In the 4th week of life, early weaned animals had 75% higher feed intake than G28 and G35 rabbits ( P,0.05). The relative weight of the liver increased by 62% between 21 and 28 days of age, and thereafter it decreased by 76% between 35 and 42 days of age ( P,0.05), with G21 rabbits having 29% higher weight compared with G35 animals on day 35 ( P,0.05). The relative weight of the whole gastrointestinal (GI) tract increased by 49% and 22% after weaning in G21 and G28 rabbits, respectively ( P,0.05). On day 28, the relative weight of the GI tract was 19% higher in G21 than in G28 rabbits, whereas on day 35 G21 and G28 animals had a 12% heavier GI tract compared with G35 rabbits ( P,0.05). Age influenced the ratio of stomach, small intestine and caecum within the GI tract; however, no effect of different weaning age was demonstrated. The pH value of the stomach and caecum decreased from 5.7 to 1.6 and from 7.1 to 6.3, respectively, whereas that of the small intestine increased from 6.8 to 8.4 ( P,0.05); the differences between groups were not statistically significant. Strictly anaerobic culturable bacteria were present in the caecum in high amounts (108), already at 14 days of age; no significant difference attributable to weaning age was demonstrable. The concentration of total volatile fatty acids (tVFA) was higher in G21 than in G28 and G35 throughout the experimental period ( P,0.05). The proportion of acetic and butyric acid within tVFA increased, whereas that of propionic acid decreased, resulting in a C3 : C4 ratio decreasing with age. Early weaning (G21) resulted in higher butyric acid and lower propionic acid proportions on day 28 ( P,0.05). No interaction between age and treatment was found, except in relative weight of the GI tract and caecal content. In conclusion, early weaning did not cause considerable changes in the digestive physiological parameters measured, but it resulted in 10% lower growth in rabbits

The Influence of Temperature Conditions on Position Control of Fluidic Muscle

Pneumatic artificial muscles (PAMs) are of special importance in the field of pneumatic drives and in robotics. Different designs have been developed, but the McKibben muscle is the most popular and is made commercially available by different companies, e.g. Fluidic Muscle manufactured by Festo Company. There are a lot of advantages of PAMs like the high strength, good power/weight ratio, good power/volume ratio, low price, little maintenance needed, great compliance, compactness, flexibility, inherent safety and usage under rough environments. The objective of this research note is to determine the error of positioning with a Fluidic Muscle at cold and at normal operating temperature of the system with sliding mode control. The results of the experiments showed that the positioning error of the Fluidic Muscle under the experimental conditions was 0.01 mm

Bicellular cage vs. collective pen housing for rabbits: Growth performance, carcass and meat quality

The aim of this study was to compare the growth performance, slaughter results, and carcass and meat quality of rabbits reared in different housing systems. To this purpose, 456 Hyplus crossbred rabbits were reared from weaning (35 d of age) until slaughter (77 d) in 40 bicellular wire net cages (28 x 40 x 28 cm; 2 rabbits/cage; 18 animals/m2); 4 small collective pens (1.40 x 1.20 m) at low stocking density (20 rabbits/pen; 12 animals/m2); 4 small collective pens at high stocking density (27 rabbits/pen; 16 animals/m2); 2 large collective pens (1.40 x 2.40 m) at low stocking density (40 rabbits/pen; 12 animals/m2); and 2 large collective cages at high stocking density (54 rabbits/cage; 16 animals/m2). The housing of rabbits in collective pens decreased final live weight (2839 vs. 2655 g; P < 0.01), daily weight gain by 10.0% (P 64 0.01), and feed intake by 10.7% (P = 0.001), compared with rabbits housed in bicellular cages, without affecting feed efficiency. At slaughter, the rabbits from collective pens showed lower live weight, carcass weight, dressing percentage (60.5% vs. 59.5%), dissectible fat proportion (3.0% vs. 2.1%), and hind leg muscle-to-bone ratio (7.53 vs. 6.63) compared with those from bicellular cages (P < 0.001); the former rabbits had shorter (P < 0.05) and thicker femurs (P = 0.01). Within the collective pens, the increase in the stocking density from 12 to 16 rabbits/m2 increased only the slaughter dressing percentage (59.4% vs. 59.8%; P = 0.05) and the femur resistance to fracture (39.9 kg vs. 45.5 kg; P < 0.01). Pen size affected meat quality: meat pH was lower (5.72 vs. 5.76 for longissimus lumborum muscle; 5.98 vs. 6.00 for biceps femoris muscle; P = 0.05) and cooking losses were higher (longissimus lumborum: 30.0% vs. 28.8%; P < 0.01) for rabbits reared in small pens compared with those in large pens. Additionally, femur maximum diameter was lower in rabbits kept in small pens compared to those in large pens (P = 0.05). In conclusion, rearing rabbits in collective pens impaired growth performance and slaughter results compared to rabbits kept in bicellular cages, regardless of stocking density or pen size. However, the skeletal development of the animals improved in collective systems, whereas meat quality was only slightly affected by the housing system