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Low dietary energy and decreased intake of herbage have been attributed to the reduced performance of grazing dairy cattle. We hypothesized that grasses with inherently greater energy would interact in a complementary way with condensed tannins (CT) in birdsfoot trefoil to increase herbage intake by grazing dairy heifers. Eight pasture treatments comprising high-sugar perennial ryegrass (Lolium perenne L.), orchardgrass (Dactylis glomerata L.), meadow bromegrass (Bromus riparius Rehmann), and tall fescue [ Schendonorus arundinaceus (Schreb.) Dumort] were established in Lewiston, Utah as monocultures and binary mixtures with birdsfoot trefoil (Lotus corniculatus L.; BFT). Pasture treatments were rotationally stocked by Jersey heifers for 105 d in 2017 and 2018, and herbage samples were collected pre- and postgrazing for each 7-d grazing period and analyzed for herbage mass, nutritive value, and apparent herbage intake. We observed differences among pasture treatments in herbage quantity and nutritive value, as well as differences in herbage intake by grazing Jersey heifers. On average, grass-BFT mixtures had greater herbage intake than grass monocultures, and every grass-BFT treatment individually had greater herbage intake than their respective grass monocultures. Using multivariate analyses, we determined that approximately 50% of the variation in herbage intake was due to nutritive and physical herbage characteristics, with the most explanatory being characteristics related to fiber and energy, followed by those related to the percent of BFT in the herbage. Grass monocultures exhibited a range of inherent dietary energy, but there was indication that an imbalance of energy to crude protein (e.g., protein deficient) reduced intake of grass monocultures. Moreover, there was some evidence of a complementary effect between increased dietary energy and CT; however, low CT levels made it impossible to determine the effect of CT on herbage intake per se. This study confirmed that chemical and physical characteristics inherent to different pasture species have a large effect on herbage intake by grazing cattle. Pastures planted to binary mixtures of nutritious grasses and birdsfoot trefoil increase herbage intake of temperate pastures by grazing Jersey heifers. [ABSTRACT FROM AUTHOR]

A complete randomized design was used to investigate the effect of increasing pasture species on herbage production, chemical composition and utilization under intensive sheep grazing. Four experimental farmlets were established, namely perennial ryegrass (Lolium perenne) only, receiving 163 kg N ha−1 year−1 (PRG); a perennial ryegrass and white clover (Trifolium repens) sward (PRGWC); a six species sward containing two grasses, two legumes and two herbs (6S); and a nine species sward containing three grasses, three legumes and three herbs (9S), each receiving 90 kg N ha−1 year−1. Ewes (12.5 ewes ha−1) and lambs rotationally grazed each farmlet from turnout post‐lambing until housing. Target pre‐grazing herbage mass (above 4 cm) was 1,200 kg dry‐matter (DM) ha−1, Target post‐grazing sward height was 4 cm for all rotations. Herbage samples were collected for DM yield, botanical and chemical composition determination at each grazing. Annual DM production of the 6S, 9S and PRG swards was similar (10.3, 9.9 and 9.9 ± 0.5 t DM ha−1, respectively) despite differences in N application. The 6S sward, however, had greater annual DM production compared to the PRGWC sward (9.1 t DM ha−1, p < 0.05). Herb proportions decreased in the 6S and 9S swards from 2015 to 2016 (p < 0.05) resulting in increased proportions of grass in these swards (p < 0.05). In conclusion, the PRGWC, 6S and 9S swards produced similar annual herbage DM from lower N inputs to PRG swards; however, maintaining the proportions of herbs is a challenge under intensive sheep grazing. [ABSTRACT FROM AUTHOR]

• Average bite mass was greater when pasture allowance was greater. • Bite mass was greatest in the first hour of grazing and then declined. • No difference in bite mass was found when cows grazed low and medium pasture mass. Dry matter intake (DMI) of herbage is a product of bite rate and bite mass and is a determinant of the performance of grazing ruminants. This research tested the effect of herbage allowance and herbage mass on average bite mass of individual dairy cows grazing perennial ryegrass herbage (Lolium perenne L.). Two experiments were conducted, one in each of winter (Experiment 1) and spring (Experiment 2). In each experiment, 24 Holstein-Friesian dairy cows grazed individual perennial ryegrass plots over 10 d. In each experiment cows grazed one of six treatments: low or medium herbage mass (1900 or 2200 kg DM.ha−1 in Experiment 1 and 2200 or 3000 kg DM.ha−1 in Experiment 2) combined with either low, medium or high herbage allowance (15, 25 or 40 kg DM.cow−1.d−1 in Experiment 1 and 20, 30 or 40 kg DM.cow−1.d-1 in Experiment 2). Grazing behaviour was measured with jaw movement sensors and DMI was determined by herbage disappearance measured with a rising plate meter daily, and at hourly intervals during the first 4 h of grazing after the morning milking. Average bite mass (g DM.bite−1) per day and per hour was determined as the mass of herbage that had disappeared in each period (g.d−1 or g. h−1) divided by number of prehension bites in that period. The combined data from two experiments was analysed by Linear Mixed Model and it was found there was no effect of herbage mass (P = 0.686) on bite mass per day. However, cows offered high herbage allowance had greater (P < 0.001) bite mass per day (0.62 g DM.bite-1) than cows offered the lowest herbage allowance (0.38 g DM.bite-1) across both experiments. The effect of herbage allowance was similar across both herbage masses. Bite mass per hour was the highest (P < 0.001) in the first hour of grazing in both experiments with average bite mass per hour across two experiments in the first hour of grazing (0.69 g DM.bite−1) greater than in the second (0.40 g DM.bite−1), third (0.35 g DM.bite−1) and fourth (0.32 g DM.bite−1) hours of grazing. We conclude that herbage allowance is a significant factor in determining bite mass and should be included in models aimed at predicting bite mass and hence daily herbage intake of grazing dairy cows. [ABSTRACT FROM AUTHOR]