[Ruminal 15N-straw degradation in sacco and the in vivo digestibility of 15N from straw in the sheep and pony].

This study measures the degradation and digestibility of a specific type of nitrogen (15N) in wheat straw when ingested by sheep and ponies. These measurements were made using a method that involves placing the straw in a nylon bag, implanting it in the animal’s rumen (a part of the digestive system), and observing how much of the substance is digested at various intervals.

Experiment Methodology

• The researchers used a technique known as the nylon-bag method to determine the degradation of dry matter and nitrogen in 15N-labelled wheat straw.
• The experiment involved four sheep (known as wethers), each surgically fitted with a rumen cannula, which is a tube inserted into the rumen to provide direct access for the nylon bag.
• The bags, each containing 15N-labelled wheat straw, were inserted into the rumen and extracted at 3, 6, or 12 hours post-incubation.

Results of Rumen Degradation

• The disappearance of dry matter in the wheat straw varied between 6 and 23 percent.
• The disappearance of 15N happened at a higher rate than the total nitrogen in the straw.
• After 12 hours, 71% of the 15N had disappeared, compared to only 25% of total nitrogen.
• Scientists calculated that the rumen microbial-N in the nylon bag increased from 31% (3 hours) to 45% (6 hours) and then 61% (12 hours).

Digestibility Experiment

• In a subsequent experiment, the digestibility of the 15N-labelled straw was assessed in both wethers and ponies.
• The apparent 15N digestibility was very similar in both species, at 53 +/- 2% for wethers and 51 +/- 2% for ponies.

Conclusion

• The study sheds light on the degradation and digestibility of 15N in wheat straw when ingested by sheep and ponies and suggests that a notable amount of nitrogen is obtained from the wheat straw during digestion.
• This could potentially inform livestock nutritional strategies, as understanding the digestion process can aid in optimizing feed formulas.