Validating the stage of maturity at harvest for barley, oat and triticale for swath grazing

Abstract

Two experiments were conducted to evaluate stage of maturity at harvest recommendation for barley, oat and triticale in a swath grazing system. Experiment 1 evaluated the in situ disappearance of dry matter (DM) and neutral detergent fibre (NDFD) of whole plant triticale. Neutral detergent fibre disappearance (P < 0.05) of triticale increased (P < 0.05) with advancing maturity from early milk (EM) to hard dough (HD). There was an interaction (P < 0.05) between incubation period and stage of maturity observed for DM degradability of triticale. Experiment 2 was a field study assessing the impacts of stage of maturity at harvest on barley, oat, and triticale evaluating forage yield, nutrient composition, dry matter intake (DMI), feed utilization, animal unit months per ha (AUM/ha), cow performance, and whole-system economics when used as a feed for beef cattle. The field study was carried out during the winters of 2015-16 (yr 1) and 2016-17 (yr 2) and evaluated three cereal crops (barley [cv. CDC Maverick], oat [cv. CDC S01] and triticale [cv. Taza]) when swathed at the soft dough stage or hard dough stages of maturity (3 × 2 factorial design with 2 replications/treatment in each year). One hundred and twenty cows (620.3 ± 18 kg) were allocated to 1 of 6 treatments that lasted 90 and 107 d in yr 1 and yr 2, respectively. Forage yield (kg/ha) measured prior to swathing was greater for crops swathed at the HD stage in comparison to SD (P < 0.05). However, there were no differences between barley, oat, or triticale (P = 0.07) in yield. Crude protein (CP) decreased from 12 to 11% as crops matured and total digestible nutrients (TDN) increased from 55.7 to 61.0% (P < 0.05). Dry matter intake was not different among treatments (P = 0.78). Animal unit month per ha increased for crops harvested at the HD maturity in comparison to SD (11.5 vs. 9.15 AUM/ha; P < 0.05). There were no differences observed for final body weight (P = 0.10) or final body condition score (P = 0.60) of cows among treatments and cows were able to maintain a body condition score of 2.6 throughout the grazing period. Total production costs were greater for crops harvested at soft dough ($1.80/cow/d) than hard dough ($1.52/cow/d; P < 0.05). Total production costs were least for triticale ($1.36/hd/d) and the most for barley ($1.92/cow/d; P < 0.05). Results from the current studies suggest delaying swathing until hard dough increased forage yield, decreased CP concentrations but increased TDN, increased AUM/ha, and reduced system cost without affecting the performance of cows. Based on these results, the current recommendation for maturity at time of harvest may need to move from soft dough to hard dough to maximize whole-plant potential of barley, oat and triticale in swath grazing systems.