This experiment was conducted to evaluate the effects of lower dietary crude protein (CP) level on performance, egg quality and nitrogen balance in laying hens under standard ileal digestible (SID) amino acid (AA) pattern. A total of 540 healthy Hy-Line W36 laying hens aged 20 weeks with similar body weight were randomly allotted to one of five treatments (18.0%, 17.5%, 17.0%, 16.5% and 16.0% of CP) with the metabolizable energy (ME) of 11.82 MJ/kg and SID Lys of 0.831% under the same AA pattern. Each treatment consisted of six replicates with 18 birds per replicate. The results showed as follows: under the SID amino acid pattern, lowering dietary protein level significantly affected average egg weight (P<0.01), CP intake (P<0.01), albumen height (P<0.05) and nitrogen intake and excretion (P<0.05), and a trend of improving the nitrogen apparent availability was also shown up (P=0.05). Data analyses of Pearson correlation and Pearson partial correlation showed that the declined average egg weight had significant correlation with the reduction of dietary essential amino acids, such as Arg, Phe and Leu beyond SID AA pattern used (P<0.05), but declined albumen height had not (P>0.05). In conclusion, lowering dietary CP level rarely affects performance, egg quality and blood biochemical indices except for average egg weight and albumen height, and the decrease of average egg weight is related to the deficiency of Arg, Phe and Leu in the diets. Applying SID AA pattern in low protein diets, performance of laying hens maintains well, while nitrogen excretion is significantly declined.
FU Shengyong
,
WU Shugeng
,
ZHANG Haijun
,
YUE Hongyuan
,
DONG Yan
,
QI Guanghai
. Effects of Lowering Dietary Protein Level on Performance, Egg Quality and Nitrogen Balance in Laying Hens under Standard Ileal Digestible Amino Acid Pattern[J]. Chinese Journal of Animal Nutrition, 2012
, 24(9)
: 1683
-1693
.
DOI: 10.3969/j.issn.1006-267x.2012.09.010
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