Strip grazing: Changes in biomass, nutrient content and digestibility of temperate, midsummer pasture by strip-grazed or ‘free’-grazing ponies, over 4 weeks.

The research article investigates the differences in the nutritional value and digestibility of grass in pastures grazed in two different ways: strip-grazing and free-grazing. The results of the study demonstrate that strip-grazing offers a more consistent nutrient supply over time, which could be beneficial to animals vulnerable to metabolic health issues.

Study Design

• The study monitored twelve ponies over a 28 day period.
• The ponies were grazed individually in adjacent paddocks, each sized 10 meters wide.
• Paddock lengths were adjusted to contain a 28-day supply of herbage biomass based on the individual weight of each pony.
• The ponies were divided into groups for two treatment methods: free-grazing (referred to as ‘TA’, with the full 28 days’ supply made accessible immediately) and strip-grazing (referred to as ‘SG1 and SG2’).
• SG1 used a ‘lead’ fence that moved forward by 1/26th of the total paddock length each day, while SG2 had the addition of a ‘back fence’, moved at the same pace as the lead.

Feed Inspection and Method of Evaluation

• Pasture nutrient contents and estimated nutrient digestibilities were determined weekly.
• Measurements were taken on the water-soluble carbohydrate (WSC) content, crude protein, neutral-detergent fiber (NDF), and acid-detergent fiber (ADF) values.
• The calculated digestible energy (cDE) of the pastures also factored into the study.

Findings

• Over weeks 1 through 4, the mean content of WSC and crude protein in strip-grazed pastures experienced a decline.
• In contrast, values for NDF and ADF increased.
• cDE of all pastures, regardless of grazing method, diminished over time.
• By week 4, fiber contents were higher and WSC, cDE, and estimated dry matter digestibility (eDMD) were lower in TA pastures than in strip-grazed pastures.
• cDE intake of ponies in the TA group exceeded requirements by 42% in the first two weeks, compared to a surplus of 8% seen in the strip-grazed groups.
• This indicates that strip-grazing provides a more balanced, steady supply of nutrients, potentially benefiting animals prone to metabolic syndrome or other health issues related to diet.