Sowing Date and Age at Harvest Affect the Productivity, Quality and Ruminal Fermentation Degradation of Forage Teosinte (Zea mexicana L.)

Balancing maximum biomass yield with high nutritional quality and reduced environmental impact remains a primary challenge in sustainable summer forage production for livestock, a challenge intensified by competition between conventional and forage crops for agricultural land, particularly regarding planting dates and land occupation duration, which limits available livestock forage resources. To address this issue, this study evaluated the forage yield, quality, and nutritive value of teosinte (Zea Mexicana L.) under three sowing dates: 1 May, 20 May, and 10 June, and three harvest ages: 40, 55, and 70 days after sowing (DAS), under Egyptian field conditions. Results showed that delaying harvesting until 70 DAS produced the highest fresh (34.95 to 46.0 t ha−1) and dry (5.38 to 6.03 t ha−1) yields for the late sowing date (10 June). The in vitro gas production (GP) assay showed that GP was significantly higher for teosinte sown on May 20 and June 10 but declined progressively with advancing harvest age. The NH3-N concentration decreased (p < 0.05) when teosinte was sown on May 1 and harvested at 40 DAS. True organic matter degradability declined for teosinte sown on May 1, May 20, and June 10 when harvested at 70 DAS, whereas it increased at harvest ages of 40 and 55 DAS for teosinte sown on May 1 and June 10. Teosinte sown on May 1 produced significantly lower methane emissions than that sown on May 20 or June 10, regardless of harvest age (40, 55, or 70 DAS). Overall, delaying harvest until 70 DAS resulted in the highest fresh and dry matter yields but significantly decreased gas production and organic matter degradability compared to earlier harvests, which require future research to optimize the utilization of teosinte.