These experiments were conducted to determine the seasonal effects of feeding finishing pigs a reduced crude protein (CP) diet on the excretion of urine and nitrogen. The experimental diets prepared were a standard CP diet (CP 14.5%) and a low CP, amino acid-supplemented diet (CP 11.5%). Three to 8 pigs (60kgBW) were fed these diets for 10 to 14 days. The experiments were conducted twice in winter and once in summer and autumn.
In winter, the low CP diets reduced water intake and urine excretion by 17% and 25%, respectively. In summer, there was no difference in water intake and urine excretion, however the nitrogen content ratio in urine tended to decrease with a low CP diet. Although there was no difference in fecal nitrogen excretion,the low CP diets reduced urine nitrogen excretion and total nitrogen excretion by 30.5 to 40.1% and 18.6 to 24.9% in all seasons. Reduction in dietary CP had only a slight impact on DG, GF, feed conversion ratio, feces excretion, and moisture contents.

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The objective of this study was to determine ammonia emission during composting of swine manure from a low protein diet. Feces and urine of pigs fed CP 14.5% (standard) or 11.5% (low protein) diet were mixed. The percentage of urine content was 20 or 30% in each of the feces. A water adjustment for each feces was made with 55% using perlite. The composting materials were aerated after being filled in a laboratory-scale composting system. The dry matter and organic matter degradation rates were equal. Decreasing dietary CP reduced maximum concentration and amount of ammonia emission during composting to 48.8% and 43.0%. However, a higher urine addition increased ammonia emission.

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Ghrelin, a 28 amino acids gastric peptide, is thought to be involved in the regulation of feeding behavior and energy metabolism. However, to date, little is known about the regulation of ghrelin secretion in pigs. The aim of this study was to investigate whether oral glucose administration influences the ghrelin secretion in pigs. Six crossbred (LW×D) castrated male pigs were assigned to four treatments in which the pigs were given an oral administration of glucose at one of doses of 0, 1, 2 and 4g/kgBW, in a change-over trial with four experimental periods. Blood samples were taken frequently over the following 2h. Oral glucose administration decreased plasma ghrelin in a dose-dependent manner, associated with an increase in plasma glucose and insulin. Strong inverse correlations were observed between plasma glucose and ghrelin (r=−0.69), as well as between insulin and ghrelin (r=−0.59). These results indicate that ghrelin secretion may be suppressed, at least in part, by an increased plasma glucose and/or insulin level in pigs.

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We conducted a feeding trial with different levels of dietary lysine in order to control growth performance and intramuscular fat (IMF) content in longissimus dorsi (l. dorsi) muscle of growing-finishing pigs. We prepared diets of two lysine levels : control diets meeting the requirement of lysine (C diet) and low lysine diets the lysine content of which is approximately 70% of the requirement (L diet). The diets are prepared for the growing period (30 to 70kg body weight) and for the finishing period (70 to 120kg body weight), thus, in terms of lysine levels, four diets in total were prepared : C diets for the growing and finishing periods and L diets for the growing and finishing periods. In addition, sweet-potato crumbs as food co-products from a factory of local sweets were added at the level of 10% to the diets for the finishing periods in order to investigate the effects of sweet-potato crumbs on quality of longissimus dorsi (l. dorsi) muscle. There were four patterns of lysine feeding : pigs given the C diet throughout the feeding trial (CC), pigs given the C diet during the growing period and thereafter given the L diet during the finishing period (CL), pigs given the L diet during the growing period and thereafter given the C diet during the finishing period (LC), pigs given the L diet throughout the feeding trial (LL). Further, the halves of the pigs were given the diets with sweet-potato crumbs during the finishing period (IMO+) and the rest were given the diets without sweet-potato crumbs during the finishing period (IMO−). Sex of the pigs was also considered. We used in total thirty two crossbred {(Landrace×Large White)×Duroc} pigs where four teen gilts and 18 barrows were assigned to a 4×2×2 factorial design. The trial started when body weight of the pigs reached to 30kg. The pigs were allowed free access to the diets and water until their body weight reached to 120kg. At the end of the trial, carcass traits were measured and IMF contents, cooking loss, and share value of l. dorsi muscle were determined.
Feeding the low lysine diets throughout the trial tended to decrease growth rates of the pigs (P<0.1). Patterns of lysine feeding affected IMF contents in l. dorsi of pigs (P<0.05) : it was the highest in the LL group (5.7%), followed by LC group (3.9%) and CC, LC group (3.5%). Patterns of lysine feeding tended to affect share values of l. dorsi muscle (P<0.1) : it was the lowest in the LL group (1.9kgf), those of the CC and CL groups were similar (2.4kgf), and the LC group had the highest value (2.5kgf). Although growth rates and feed intake of the LC group during the growing period were lower than those of the other groups, both growth rates and feed intake were recovered during the finishing period. As a result, average growth rate of the LC group throughout the trial was as high as 998g/d. However, back fat depth of the LC group tended to be larger than the other groups (P<0.1). Adding sweet-potato crumbs to diets during the finishing period did not affect IMF contents and other traits of l. dorsi muscle.
These results indicate that growth performance, growth rate in particular, and IMF content in l. dorsi muscle can be controlled by pattern of lysine feeding in growing-finishing pigs.

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