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Sources of sulfur in protein supplements and fiber degradability
Sulfur sources in protein supplements and fiber degradability
The present work is focused on the evaluation of different sulfur sources in protein supplements for cattle. Crossbred steers were fed with Brachiaria dictyoneurahay, with different sulfur sources in the protein supplement: 70S elementary sulfur (ES70S); 98S elementary sulfur (ES98S); hydrated calcium sulfate (HCS); anhydrous calcium sulfate (ACS) and ammonium sulfate (AS). The nutritional effects observed to the steers in relation to the different sulfur sources were evaluated by means of different aspects, such as nutrient intake, apparent digestibility, fiber degradability and particle flow-rate. An 11:1 nitrogen:sulfur ratio was employed, being that five steers fistulated in the rumen and abomasum were utilized through distribution in a 5 x 5 Latin square. The different sulfur sources in the supplement did not affect (P>0.05) the intakes of dry matter of hay; crude protein (CP); neutral detergent fiber corrected for ash and protein (NDFap); organic matter (OM); nonfiber carbohydrate (NFC); ether extract (EE); and total digestible nutrients (TDN). The respective sulfur sources do not generated significant alterations (P>0.05) regarding the digestibility coefficients of NDFap and CP.
In this study, NDF degradation profiles were encountered in agreement with the solid transit kinetics parameters model and estimations. The data were adjusted to different double-compartment models (G1G1, G2G1, G3G1, G4G1, G5G1 and G6G1). The models G2G1, G3G1, G5G1, G4G1 and G3G1 were more efficient in accordance with the estimations of the following treatments: G2G1 to 70S elementary sulfur; G3G1 to 98S elementary sulfur; G5G1 to calcium sulfate (hydrated gypsum); G4G1 to calcium sulfate (anhydrous gypsum) and G3G1 to ammonium sulfate. It was possible to infer that the sulfur sources employed in the present work influenced slightly the ruminal fiber degradation.
Table 1 – Medium values and coefficients of variation (CV) for daily intake of dry matter (DM), crude protein (CP), neutral detergent fiber corrected for ash and protein (NDFap), organic matter (OM), total digestible nutrients (TDN), as function of sulfur sources in the protein supplements.
Item |
ES70S |
ES98S |
HCS |
ACS |
AS |
CV(%) |
g/kg BW |
||||||
Hay DMI |
17.08 |
17.31 |
16.71 |
17.18 |
17.11 |
4.66 |
kg/day |
||||||
CP |
0.48 |
0.47 |
0.47 |
0.47 |
0.45 |
7.46 |
NDFap |
3.76 |
3.76 |
3.60 |
3.74 |
3.79 |
4.90 |
OM |
4.19 |
4.17 |
4.00 |
4.14 |
4.18 |
5.14 |
NDT |
3.04 |
3.15 |
2.73 |
2.51 |
2.62 |
17.67 |
Keywords: degradability, fiber, intake, nitrogen sulfur ration