Protein, nucleic acid content and activity of μ- and m-calpain in thelongissimus dorsimuscle as affected by protein and energy restriction during early growth of pigs

The Effect of Decreased Protein Levels in Sow Diets on Nitrogen Content of Faeces and Physiological Parameters of Blood

The research material consisted of 42 sows divided into 3 feeding groups, 14 individuals in each group, which received feed mixtures with different protein levels. Protein and amino acid levels in the control group were in accordance with recommendations contained in Polish standards. The level of protein in experimental groups was decreased by 10 and 20%, respectively, and the levels of lysine, methionine, threonine and tryptophan were adjusted to those of the control group. During the gestation and lactation periods all sows were fed individually. The content of dry matter, nitrogen, fibre, fat and ash was determined in samples of faeces collected at 60 and 105 days of pregnancy, and the total nitrogen content was assessed in urine. Blood from sows was collected on day 14 of lactation, and indices of protein, fat transformation and mineral components content were determined in blood serum. The results of the analysis of faeces and urine prove that pregnant sows from the experimental groups excreted 7% and 10% less nitrogen in faeces, and 18% and 23% less urine in faeces. The reduced protein level in feed mixtures did not significantly influence the content of dry matter, fibre and ash in faeces. A significant decrease in the content of total protein, globulins, urea and an increase in cholesterol level was observed in the blood serum of sows from both experimental groups. No influence of the reduced protein level in feed on the content of mineral compounds in blood serum or haematological parameters of the sows' blood was noted.

Profile of fatty acids, muscle structure and shear force of musculus longissimus dorsi (MLD) in growing pigs as affected by energy and protein or protein restriction followed by realimentation

Forty-eight gilts were submitted to a 30% restriction of feed (groups F and F1) or protein intake (group P) from 90 to 118 days of age, followed by realimentation from 119 to 168 days of age. Control pigs (C) were fed during the whole experiment according to a semi ad libitum scale. During realimentation all animals were fed according to semi ad libitum scale except pigs F1 which were fed ad libitum. Six pigs from each group were slaughtered at the end of restriction and realimentation. Restriction decreased the weight of musculus longissimus dorsi (MLD) and increased shear force. Restriction of feed intake depressed MUFA concentration and increased n-6/n-3 ratio while protein restriction decreased n-6/n-3 and PUFA:SFA ratios. Structure of fibers was not affected. After realimentation MLD mass was still lower in all previously restricted pigs, shear force was the lowest in F1 pigs. Only percentage of fast twich oxidative fibers was significantly greater in F1 pigs than in others. Significant correlations between parameters investigated during the study were found.