RESEARCH ▶▶▶
Dietary betaine improves bone strength in laying hens
Betaine is a widely used feed additive in the poultry industry, mainly due to its ability to reduce heat stress. New research by the University of Edinburgh has unveiled a twist in the use of betaine – its role in improving bone strength in laying hens.
BY MATTHEW WEDZERAI, CORRESPONDENT B
Results show that the addi- tion of betaine in the diet does not significantly affect egg pro- duction and quality.
one fractures and other forms of skeletal damage are a challenge for laying hens; the fractures are usually the result of progressive osteoporosis. Osteo porosis in hens is ultimately the result of the
physiological changes that occur because of the start of re- productive activity. The research was designed to evaluate the effects of dietary betaine on bone quality, plasma homo- cysteine, and egg production in laying hens. The researchers also compared the effects of dietary betaine to two levels of phytase (300 and 1000 FTU/kg). The methyl-donor properties of betaine were key in reducing the concentrations of homo- cysteine, which makes a greater contribution to bone quality.
The research Lohmann day-old chicks were used in this study to assess the effects of dietary betaine on bone strength. Dietary betaine
was also compared to phytase included at two levels (300 FTU/ kg and 1000 FTU/kg). Four diets were used as follows: (1) con- trol (0 mg/kg betaine), (2) Betaine (1000 mg/kg), (3) Phytase (300 FTU/kg), and (4) Phytase (1000 FTU/kg). Measurements of bone strength were taken at 45 and 70 weeks of age.
Bone strength Previous studies show a negative correlation of homocysteine and bone strength. In this study, the focus was more on the effects of betaine on plasma homocysteine levels and how this contributes to better bone strength. Bone strength was measured in tibia, humerus and keel. Betaine, in this study, significantly lowered the levels of homocysteine, but phytase had no effects on homocysteine concentrations.
Lowering plasma homocysteine In this study, hens that were fed betaine had lower concen- trations of homocysteine than hens not receiving betaine. Hens with higher concentrations of plasma homocysteine had poorer bone strength. This was evident in the tibia and humerus breaking strength, and tibia density, which was higher in birds fed betaine. The researchers identified the me- thyl-donor properties of betaine as key in reducing the con- centrations of homocysteine, which makes a greater contri- bution to bone strength. They emphasised the importance of understanding how high levels of homocysteine negatively affect bone strength. “Homocysteine is involved in the trans-methylation cycle, where it can be re-methylated into methionine through the re-methylation pathway. Betaine acts as a methyl donor to enhance the conversion of homo- cysteine to methionine, thus influencing the level of homo- cysteine. There is considerable evidence that high homocyst- eine levels affect collagen cross-linking and hence contribute to osteoporosis. Collagen crosslinks contribute to the struc- tural strength of the bone. High concentrations of homocyst- eine affect the enzyme lysyl oxidase, which disrupts stable collagen cross-link formation. In addition, homocysteine in- creases bone resorption by stimulation of osteoclast forma- tion and activity through increased intracellular reactive
30 ▶ ALL ABOUT FEED | Volume 29, No. 3, 2021
PHOTO: HENK RISWICK
PHOTO: KASTERMANS STUDIOK
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