Pigs of Belgian Landrace (B), Duroc (D), Hampshire (H), and Pietrain (P) breeds were slaughtered at 90, 110 and 130
kg body weight (BW) and the carcass chemical composition and fatty acid profiles of ...intramuscular fat of loin and backfat were determined. The carcass of Pietrain pigs had a higher concentration of protein and less fat than of B, D and H breeds. In tissues, the PUFA:SFA ratio was lower in the heavier (130
kg BW) than in lighter pigs (90 and 110
kg BW). This feature was higher in P pigs compared with the other breeds. The backfat had a higher concentration of PUFA:SFA ratio than intramuscular fat. The PUFA
n−
6:
n−
3 ratio was not affected by the breed and weight of pigs, but it was lower in backfat than in longissimus muscle fat. The protein concentration in the carcass was positively related to PUFA and negatively to SFA concentration in tissues.
Forty-eight gilts were used to investigate the effects of a 30% restriction of feed (groups F) or protein (group P) in the period from 90 to 118 days of age on performance and on bone growth and ...mineralization between 119 and 168 days of age, when all of the pigs were fed an adequate diet at approximately 95% of ad libitum, with the exception of those in one of the previously feed-restricted groups, which were offered the same diet ad libitum (F1). During the entire experiment, control pigs (C) were fed according to a semi ad libitum scale. Half of the pigs from each treatment were slaughtered at the end of periods 1 and 2, and the femur and the third and fourth metacarpal and metatarsal bones were removed and weighed. Bone mineral content (BMC) and density (BMD) were determined using a DXA scanner (NORLAND). Pigs subjected to the feed and protein restrictions in period 1 were 17% (P<0.001) and 7% (P<0.001) lighter, respectively, at 118 days of age than their control counterparts. The femur and other bones of feed-restricted pigs were also significantly lighter, and their BMC and BMD significantly lower at 118 days than those of the controls. Protein restriction had no significant effect, however, on bone weight or mineralization at 118 days of age. After 118 days of age, F1 pigs grew significantly faster than pigs on all of the other treatments and were heavier at 168 days of age than control, P-, and F-treatment pigs. At 168 days, F-treatment pigs grew faster and were of a similar weight (P>0.05) as controls, whereas P pigs exhibited similar growth as controls. There were no significant differences in bone weight or BMC between treatments at 168 days of age, but BMD was significantly higher in the femur and fourth metatarsal bones of F- and P-treatment pigs compared with control animals. The results indicate that young pigs subjected to short-term deficiency of protein and energy intake were able to recover and even surpass the parameters of bone/skeletal mineralization compared with adequately fed pigs.
The aim of the experiment was to determine the effect of different strategies of pig nutrition (restriction and realimentation) on histochemical traits in Longissimus lumborum (LL), Biceps femoris ...(BF) and Semitendinosus (ST) muscles. Reduced energy and protein intake contributed to a significant decrease in the weight of LL muscles during controlled growth and in the weight of LL, BF and ST muscles at 168 days of age. After the restricted feeding period, it was found that reduced intake of protein and energy or of protein alone had a significant effect on the proportion and diameter of fast-twitch glycolytic (FTG) fibres. After realimentation, no differences in muscle structure were found between the investigated groups of animals. Regardless of the feeding system, the growth of pigs was paralleled by hypertrophy of all muscle fibre types and their different transformation in the muscles.
Based on the results on the study it may be concluded that the growth rate of pigs is much more sensitive to energy than protein restriction in the diet. The kind of underfeeding influences the fat ...content in the body and pigs consuming inadequate amounts of energy have decreased, while those consuming inadequate amounts of protein have increased fat stores. The growth of internal organs is much more sensitive to energy than protein restriction and the organs whose growth in most inhibited are the liver and small intestines. Compensdatory growth takes about 2-3 weeks after the change from restriction to realimentation and a recovery of body physical and chemical composition but not age of previously underfed animals is possible
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