The objective of this experiment was to determine the net energy requirements for maintenance of growing and finishing pigs using regression models. Thirty-six growing (27.38 ± 2.24 kg) and 36 finishing (70.25 ± 2.61 kg) barrows were used and within each phase. Pigs received a corn-soybean meal diet fed at 6 levels of feed intake, which were calculated as 0, 20, 40, 60, 80, or 100% of the estimated ad libitum ME intake (2,400 kJ ME/kg BW(0.6)·d(-1)) of the pigs. Measurements were conducted on 6 pigs per feeding level and per stage of growth. After a 5-d adjustment period, barrows in the fasted treatment were kept in respiration chambers for 2 d to measure the fasting heat production. Barrows in the other treatments were kept individually in respiration chambers for a 5-d balance trial followed by a 2-d fasting period. Heat production (HP) in the fed state was measured and feces and urine were collected in the balance trial. The total HP increased (P < 0.01) with increasing feeding levels. Fasting HP increased (P < 0.01) as previous feeding level increased and was less (P = 0.012) in finishing pigs than growing pigs if calculated per kilogram BW(0.6) per day. When using an exponential regression analysis, ME requirements for maintenance were estimated at 973 and 921 kJ/kg BW(0.6)·d(-1) and NE requirements for maintenance were estimated at 758 and 732 kJ/kg BW(0.6)·d(-1) for growing and finishing pigs, respectively. The efficiencies of using ME for growth and for maintenance were estimated at 66 and 78.7% for growing and finishing pigs, respectively. It is concluded that exponential regression between HP and a wide range of ME intake may be used as a new method to determine the NE requirement for maintenance.
Five hundred and four 40-wk-old Brown Dwarf hens (1.51 +/- 0.08 kg BW) were fed corn-soybean meal diets containing 0, 1, 2, 3, 4, 5, or 6% conjugated linoleic acid (CLA) for 56 d to measure the effects of dietary CLA on laying hen productivity and egg quality during refrigerated storage. Four hens were placed in 1 cage, and 3 cages were grouped as 1 replicate resulting in 6 replicates per treatment. After feeding the experimental diets for 11 d, eggs were collected to determine the fatty acid composition of egg yolks. From d 12 to 18, eggs from hens fed diets containing 0, 2, 4, and 6% CLA diets were stored at 4 degrees C for up to 28 d. At designated times (1, 14, or 28 d), eggs were taken, broken, and shelled to evaluate water content, pH, and ion concentration. Firmness of hard-cooked egg yolk was also determined. With increased dietary CLA, feed intake, BW gain, rate of egg production, egg weight, and feed efficiency all decreased linearly (P < 0.01). The weight of the yolk, albumen, and shell decreased linearly (P < 0.01) with increasing dietary CLA. Concentration of CLA in the yolk lipids increased quadratically (P < 0.01), with increasing dietary CLA. Concurrent increases (P < 0.01) in the concentration of myristic, palmitic, and stearic acids and decreases (P < 0.01) in oleic, linoleic, linolenic, and archidonic acids in egg yolk lipids were observed. Days of storage and CLA (P < 0.01) increased yolk firmness. Egg yolk water content and pH increased with storage and CLA content (P < 0.01). Corresponding decreases were observed in albumen pH. Regardless of dietary treatment, the concentrations of Na, K, and Mg in egg yolks increased with longer storage time. At 28 d of storage, there was a linear (P < 0.01) increase in Na, K, and Mg content in egg yolks as dietary CLA increased. In contrast to the egg yolk, the concentrations of Na, K, and Mg in egg albumen decreased with storage time. On d 28, there was a linear decrease (P < 0.01) in the Na content of albumen with increasing CLA. This study suggests that the greater firmness of CLA-fed eggs might be related to the change of pH, water content, and ion concentrations during refrigerated storage.
Braised chicken is a traditional ready-to-eat poultry product produced by frying chicken coated with maltose or honey and then boiling it in a soup that is circularly used. This study examined the effects of the frying time, honey concentration, boiling time, and cycle times of the soup on the formation of heterocyclic amines (HA), a class of mutagenic/carcinogenic compounds generated in heated muscle meat. Nine HA in chicken and recycled soups were analyzed by HPLC with UV and fluorescence detection. 1-Methyl-9H-pyrido[3,4-b]indole (Harman), 9H-pyrido[3,4-b]indole (Norharman), and 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) were detected in most samples, and the amount of each HA increased with the frying or boiling time. Chicken skin was found to have higher HA content than chicken meat. More HA were detected in the soup than in the chicken, in most cases. 2-Amino-3-methylimidazo[4,5-f]quinoline and 2-amino-3,4,8-trimethylimidazoquinoxaline (4,8-DiMeIQx) were also detected in chicken and soup circularly boiled 20 times, and the total amount of HA reached 68.80 and 96.98 ng/g in chicken and soup, respectively.
A total of 216 Brown Dwarf laying hens (1.62 +/- 0.06 kg BW and 60 wk old) were fed 1 of 3 corn-soybean meal-based diets containing 0, 2.5, or 5.0% conjugated linoleic aicd (CLA) to explore its effects on the fatty acid composition of egg yolk, plasma, and liver as well as hepatic stearoyl-coenzyme A desaturase-1 (SCD-1) activity and its mRNA gene expression. Four hens were placed in wired-floored cages (45 x 40 x 45 cm) and 3 cages were grouped as 1 replicate, resulting in 6 replicates per treatment. The experimental diets were fed for 54 d, and then eggs were collected to determine the fatty acid composition of egg yolk. Four eggs were randomly selected from the total day's production for each replicate, and the contents were pooled prior to analysis. On d 56, one randomly chosen hen from each replicate (6 hens per replicate and a total of 18 hens) was bled via heart puncture and then killed in order to collect liver samples to measure the fatty acid profile of plasma and liver tissue as well as hepatic SCD-1 activity and its mRNA abundance. Dietary supplementation of CLA resulted in a significant deposition of CLA in egg yolk, plasma, and liver lipids (P < 0.01). As the dietary level of CLA increased, the concentration of saturated fatty acids in egg yolk, plasma, and liver also increased (P < 0.05). However, the concentration of monounsaturated fatty acids in these same tissues decreased (P < 0.01). Compared with the control, the activity of SCD-1 was reduced by feeding 2.5% CLA (P < 0.05) without a change in SCD-1 mRNA gene expression. However, feeding 5% CLA reduced both SCD-1 activity and mRNA abundance (P < 0.05). These results indicate that the conversion of saturated to monounsaturated fatty acids in egg yolk, plasma, and liver might be modulated directly at hepatic mRNA gene expression levels, or may be indirectly regulated at the downstream post-transcriptional levels.
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