In vitro ruminal fermentation, methane production and nutrient degradability as affected by fruit and vegetable...

Area of Science:

• Agricultural Science
• Animal Nutrition
• Food Science

Background:

• Pomaces are by-products of the food industry with potential for use as sustainable animal feed.
• Ruminant nutrition can be enhanced by incorporating alternative feed sources to improve sustainability.
• Investigating the effects of pomaces on rumen fermentation is crucial for their effective utilization.

Purpose of the Study:

• To evaluate the fermentation characteristics of various dried fruit and vegetable pomaces in ruminant diets.
• To assess the impact of pomaces on gas production, methane emissions, and digestibility in vitro.
• To analyze the polyphenol content of pomaces and correlate it with fermentation outcomes.

Main Methods:

• An in vitro Hohenheim Gas Test was employed using rumen fluid from fistulated cows.
• Six fruit pomaces (apple, aronia, orange, pomegranate, red grape, white grape) and three vegetable pomaces (beetroot, carrot, tomato) were tested.
• Pomaces were supplemented at three concentrations (150, 300, 500 g kg⁻¹ DM) to a basal hay diet, with analysis of gas, SCFA, digestibility, microbial counts, and polyphenols.

Main Results:

• Most pomaces did not significantly alter rumen fermentation at tested dosages.
• Aronia pomace decreased organic matter digestibility at the highest concentration.
• Apple, carrot, and beetroot pomaces increased gas formation relative to digestible organic matter.
• Pomegranate pomace significantly reduced methane production by 28% at 500 g kg⁻¹ DM without affecting digestibility.

Conclusions:

• Pomaces can generally be used in ruminant nutrition without adverse effects.
• Pomegranate pomace, particularly due to its high hydrolysable tannin content, shows promise as a methane-mitigating feed supplement for ruminants.
• Further in vivo studies are recommended to validate the methane-reducing potential of pomegranate pomace.