|Buhr, Richard - Jeff|
Submitted to: Poultry Science Association Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/2/2005
Publication Date: 7/31/2005
Citation: Webster, A.B., Buhr, R.J., Dale, N.M., Jardim, R.M. 2005. Dietary fluoride fed during growth on bone strength of caged laying hens [abstract]. Poultry Science Association Meeting. 84(supp 1):81. Interpretive Summary:
Technical Abstract: 500 Hy-Line W-36 pullets were raised on the floor and fed one of five diets containing 0, 50, 100, 200, or 400 ppm fluoride (F), provided in the form of sodium fluoride (NaF), from day 1 to 16 weeks of age. Feeds were formulated according to the Hy-Line management guide, with Na level being made equal for all the diets. At 16 weeks, 20 pullets per treatment were weighed and sacrificed. The left humerus, femur, and tibiotarsus of each bird were excised and cleaned of soft tissue by dissection. After measuring weight and length, each bone was broken in a Instron machine to determine maximum breaking load. The free thoracic vertebra (FTV) and the proximal section of the tarsometatarsus (PTM) were fixed in formalin for subsequent preparation of slide sections for histomorphometric assessment of bone components. The remaining pullets were housed, 2 per cage, in the UGA layer house, where they were photostimulated and fed the UGA layer ration, without NaF. At 30 and 45 weeks of age, additional sets of 20 pullets per treatment were sacrificed and data collected as described above. Live-bird palpation scoring of severity of deformity at the costochondral junctions of the ribs was conducted at 20, 28, 35, and 45 weeks. A six-point scale (0-5) was used with 0 indicating no rib deformity and 5 denoting gross deformation of the rib cage. Egg production was recorded from 19-30 weeks and 41-43 weeks. Dietary fluoride provided from 0-16 weeks resulted in statistically significant increases in bone strength at all ages (P<.05). The improvement was most pronounced for birds fed 400 ppm F. At 45 weeks, the maximum breaking loads for the humerus, femur, and tibiotarsus of these birds averaged 37, 24, and 22% greater, respectively, than those for the control hens, although the bones were significantly shorter by 2.1, 2.0, and 2.9 mm, respectively. 400 ppm F significantly increased humerus weight but not femur or tibiotarsus weight. Rib palpation scores were low (few and slight deformities) until 36 weeks and increased considerably by 45 weeks, at which time the birds in the 50 ppm F treatment had the best scores. Birds fed 400 ppm F were significantly lighter than control birds (e.g. 1136 vs. 1162 g at 16 weeks, and 1612 vs. 1768 g at 45 weeks). Egg Histomorphometric evaluation of the FTV and PTM remain to be completed.