Researchers compared goats that ate grass in abandoned rice fields with goats kept in pens and fed hay and grain. Both groups of goats grew similarly well until September, but the grazing goats ended up slightly smaller by the end of the study. The scientists measured chemicals in the goats’ blood to understand how well they were eating and how the plants in the field were growing. This research suggests that blood tests could help farmers know when grazing fields have enough food for their animals and when the goats are getting proper nutrition.

The Quick Take

  • What they studied: Whether goats grow better when allowed to graze and eat grass in old rice fields compared to goats kept in pens and fed stored hay and grain
  • Who participated: Eight young Saanen goats (a dairy breed) that were 4 months old at the start, split into two equal groups—one grazing outdoors and one kept in pens
  • Key finding: Both groups grew at similar rates until late September, but grazing goats weighed slightly less at the end of the 6-month study period. Blood tests showed that grazing goats’ nutrition levels changed throughout the season as plants grew and died back.
  • What it means for you: If you raise goats for meat, grazing in abandoned fields may work, but you might need to add extra grain to help them reach their full size. Blood tests could help you know when your grazing field is running out of food.

The Research Details

Scientists divided eight young goats into two groups in May. One group grazed freely in an abandoned rice field and received extra grain (1.2% of their body weight daily). The other group stayed in pens and ate stored grass hay plus grain (1.0% of their body weight daily). The study lasted from late May through early November—about 6 months. Researchers measured how much the goats weighed each month, tested their blood regularly, and tracked what plants were growing in the grazing field and how much the goats were eating.

The grazing field contained mainly two types of wild plants: a tall grass called cogon grass and a plant called ramie. The scientists measured how much plant material was available each month and noticed the plants grew most in August, then declined as fall arrived.

This approach allowed researchers to see real-world differences between the two feeding systems and understand how blood chemistry changes when goats graze on natural plants versus eating prepared feed.

This study design reflects how farmers actually raise goats in some parts of the world, making the results practical and useful. By measuring blood chemicals, the researchers found a way to monitor whether grazing goats are getting enough nutrition without constantly weighing them. This could help farmers make better decisions about when to move goats to new fields or add more grain.

This was a small study with only 8 goats total, which limits how much we can generalize the findings to all goat farms. The study lasted one season, so we don’t know if results would be similar in different years or climates. The researchers used standard scientific methods for measuring weight and blood chemistry, which strengthens confidence in those specific measurements. However, the small group size means results should be viewed as preliminary findings that suggest directions for future research rather than definitive answers.

What the Results Show

Both groups of goats gained weight steadily from May through September, with no meaningful difference between grazing and pen-raised goats during this period. However, from September through November, the grazing goats gained less weight than the pen-raised goats, resulting in the grazing group being noticeably lighter at the end of the study.

The plants in the grazing field peaked in August—this is when the most plant material was available for the goats to eat. After August, the amount of available plants decreased significantly, which likely explains why grazing goats grew more slowly in the final months.

Blood tests revealed that grazing goats had changing levels of various nutrients throughout the study. These included urea (a nitrogen waste product), cholesterol, fatty acids, lactate (a muscle byproduct), amino acids (protein building blocks), and phytanic acid (a compound from plants). In contrast, pen-raised goats had more stable blood chemistry because they received consistent feed daily.

The researchers identified that two specific plant species dominated the grazing field: cogon grass and ramie. These plants provided adequate nutrition early in the grazing season but became less abundant and possibly less nutritious as fall approached. The fluctuating blood chemistry in grazing goats appeared to reflect these changes in plant availability and quality. This suggests that blood tests could serve as an early warning system—when certain blood chemicals change, it signals that the grazing field may be running low on good food.

Previous research has shown that grazing systems can be economical for goat farming because animals find their own food. This study adds important information by showing that while grazing works well during peak growing season, supplemental grain becomes increasingly important as natural plants decline. The finding that blood chemistry reflects field conditions aligns with earlier research suggesting that blood tests can indicate animal nutrition status, but this is one of the first studies to connect blood chemistry specifically to grazing field conditions.

The study included only 8 goats, which is a very small number. Results from such a small group may not apply to larger herds or different goat breeds. The study ran for only one season, so we don’t know if these patterns would repeat in other years with different weather. The research was conducted in Japan with specific plant species, so results may differ in other climates or regions with different vegetation. Additionally, the study didn’t test whether adding more grain to grazing goats in fall would have helped them catch up in weight to the pen-raised group.

The Bottom Line

If you raise goats for meat and have access to abandoned fields, grazing appears to be a viable option, especially from spring through early fall. However, plan to increase grain supplementation in late summer and fall when natural plants become scarce. Moderate confidence: Blood tests could help monitor your grazing goats’ nutrition, but this would require working with a veterinarian to establish normal ranges for your situation.

Goat farmers in regions with abandoned agricultural land, particularly those interested in lower-cost production methods. This is especially relevant in areas with seasonal plant growth patterns. This research is less applicable to farmers in year-round warm climates or those with access to high-quality pasture. It may not apply to dairy goat operations, which have different nutritional requirements than meat goats.

Goats on this grazing system grew normally through the first 4 months (May-September). Weight differences became apparent in months 5-6 (October-November) when plants declined. If you implement this system, expect to see good growth during peak plant season but plan for slower growth as plants decline in fall. Full benefits of monitoring blood chemistry would take several months to establish baseline patterns for your specific situation.

Want to Apply This Research?

  • Track your goats’ monthly weight and note the date when you observe plant growth declining in your grazing field. Record when you increase grain supplementation and correlate this with weight gain rates. This creates a simple record to improve your system year to year.
  • If using a farm management app, set monthly reminders to weigh your grazing goats and assess field conditions. In late August or early September, schedule a reminder to increase grain supplementation before plant decline causes slower growth. Document which fields work best and when plants typically peak in your region.
  • Over multiple seasons, track the relationship between plant availability in your fields and your goats’ growth rates. Work with a veterinarian to establish baseline blood chemistry values for your herd, then use periodic blood tests (perhaps monthly during grazing season) to detect early signs of nutritional stress before it affects weight gain. This long-term data helps you optimize grazing management and supplementation timing.

This research describes results from a small study of 8 goats over one season and should not be considered definitive guidance for all goat farming operations. Results may vary significantly based on climate, plant species, goat breed, and individual farm conditions. Before implementing major changes to your goat feeding system, consult with a veterinarian or animal nutritionist familiar with your specific situation. Blood chemistry testing should only be performed and interpreted by qualified veterinary professionals. This summary is for informational purposes and does not replace professional agricultural or veterinary advice.