# The Botanical Composition of the Diet of Grazing Cows During the Dry Season in a Subtropical Region of Mexico

## TL;DR

This study identifies the plants cows eat during dry seasons in Mexico and how these plants meet their nutritional needs.

## Contribution

The study provides new insights into the use of alternative forages like shrubs and trees to sustain cattle during dry seasons.

## Key findings

- Cows consumed Cynodon plectostachyus and woody species like Vachellia farnesiana during the dry season.
- These forages met 47-63% of the cows' dry matter, energy, and protein needs.
- Alternative forages help sustain cattle when pasture resources are scarce.

## Abstract

Tropical and subtropical cattle production systems use local resources to produce milk and beef under extensive grazing with limited supplementation during the dry season. Lactating cows graze in complex agroecosystems composed of native and introduced grasses in pastures with scattered shrubs and trees that are part of the cows’ diets, with varied nutritional composition. Our results provide information about the botanical composition of the cows’ diet and the nutrients obtained from forages like Cynodon plectostachyus and the woody species Vachellia farnesiana, Pithecellobium dulce, Guazuma ulmifolia, and Ficus sp. Knowledge of the alternative fodder resources consumed by the cows and their nutritional contributions can be used to develop efficient and sustainable management practices.

The introduction of livestock into tropical and subtropical forest areas has displaced the original forest vegetation. Posterior surges of secondary vegetation have served as a source of alternative forage to cattle during scarcity periods. The objective of this study was to determine the botanical composition of cows’ diet (BCD) and the productive performance of lactating Brown Swiss cows during the dry season. The BCD was determined through microhistological analysis of faecal samples of grazing cows. Grazing areas were sampled to determine morphological and botanical composition (BCP). Forages were sampled to determine their chemical composition. Cows’ productive variables were recorded during March, April, and May of 2012. The BCP and BCD consisted of Cynodon plectostachyus and the woody species included Vachellia farnesiana, with smaller proportions of Pithecellobium dulce, Guazuma ulmifolia, and Ficus sp. These forages contributed 63, 48, and 47% of the dry matter, metabolizable energy, and metabolizable protein requirements of the cows. Therefore, it is concluded that alternative forages contributed significantly to addressing nutritional requirements during periods of pasture scarcity. Understanding the botanical composition of the diet of grazing cows allows for the development of management strategies based on the efficient use of local resources.