Abstract
The objective of this study was to evaluate the effects of dietary inclusion of protected sodium butyrate (PSB) on the intestinal development and feed nutrient metabolizability of commercial laying hens. The birds started to receive the treatment rations at 58 weeks of age. At 76 weeks of age the laying hens were distributed in a randomized block design to four treatments (0, 105, 210 and 300 g t-1/PSB), six replicates, and two birds/replicate. The nitrogen balance (NB), ether extract balance (EEB), dry matter metabolizability coefficient, nitrogen, ether extract, ash, apparent metabolizable energy (AME), and AME corrected by nitrogen (AMEn) were evaluated. For assessment of intestinal development, we evaluated the duodenum, jejunum, ileum, cecum, and colorectal lengths, the relative intestine weight and villus height, crypt depth, and villus:crypt ratio of the duodenum, jejunum, and ileum. A decreasing linear effect was observed in the duodenum length, while an increasing linear effect was observed in the height of the duodenum and jejunum villi. A quadratic effect was found in the jejunum crypt depth. A linear increasing effect was found on the villus:crypt ratio of the duodenum and jejunum, and a quadratic effect was observed in the ileum. Quadratic and increasing linear effects were observed in the NB and EEB, respectively. Additionally, increasing linear effects were observed in the AME and AMEn. The dietary addition of 300 g t-1 of PSB improved intestinal development and energy metabolizability of the diet.
Highlights
They lay larger eggs with reduced shell thickness owing to the larger egg surface area; the calcium carbonate deposition per unit surface area decreases because the egg weight increase rate is higher than the shell volume increase rate in eggs laid by ageing birds (Carvalho et al, 2013; Oliveira et al, 2020)
Based on the bromatological analyses, we calculated the nitrogen balance (NB), ether extract balance (EEB), dry matter metabolizability coefficient (DMMC), nitrogen metabolizability coefficient (NMC), ether extract metabolizability coefficient (EEMC), ash metabolizability coefficient (AMC), apparent metabolizable energy (AME), and AME corrected by nitrogen (AMEn) using the equations proposed by Sakomura & Rostagno (2016)
The regression analysis showed that the addition of dietary protected sodium butyrate did not have an effect on the intestinal morphometry of laying hens at 76 days of age (Table 2)
Summary
They lay larger eggs with reduced shell thickness owing to the larger egg surface area; the calcium carbonate deposition per unit surface area decreases because the egg weight increase rate is higher than the shell volume increase rate in eggs laid by ageing birds (Carvalho et al, 2013; Oliveira et al, 2020). Older birds have reduced ability to absorb calcium through the intestine owing to a reduction in their capacity to convert the inactive form of vitamin D into its active form; their retention rate of absorbed calcium is lower, as is their ability to mobilize bone calcium, owing to the lower enzymatic activity of carbonic anhydrase, which leads to reduced eggshell calcification (Vilela et al, 2016). According to Sengor et al (2007), as the birds get older, the intestinal mucosa cells weaken, thereby leading to a reduction in duodenal villus height, which hampers the absorption of the nutrients required for eggshell formation. Sodium butyrate [Na(C3H7COO)], is a four-carbon short-chain organic acid in the form of a soluble salt derived from butyric acid; it can be used in its free or protected form in animal feeds. In its protected form, sodium butyrate is gradually released into the digestive tract, thereby increasing its mode of action at several parts of the intestine (Vallejos et al, 2015; Santos Junior et al, 2016)
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