The objective of this study was to determine how harvest maturity of whole-crop cereals commonly used in swath grazing systems in western Canada affects yield, chemical composition, and in situ digestibility. We hypothesized that the increase in yield with advancing maturity would not offset the decline in digestibility and, thus, the yield of effectively degradable DM (EDDM) would decline with advanced stages of maturity. Four replicate plots of barley (Hordeum vulgare L.; cv. CDC Cowboy), millet (Panicum milliaceum; cv. Red Proso), oat (Avena sativa L., spp.; CDC Weaver), and wheat (Triticum aestivum L.; cv. 07FOR21) were grown, with a subsection in each replicate harvested at 4 different maturities: head elongation, late milk, hard dough, and fully mature. At each stage of maturity, the wet and DM yields, and chemical composition (DM, OM, NDF, crude fat, and nonfiber carbohydrates; NFC) were determined. Whole-crop samples were ground (2-mm screen) and weighed into nylon bags (pore size of 53 ± 10 µm), and duplicate incubation runs were conducted by crop type. For each incubation run, nylon bags were randomly allocated (randomized by field replication, stage of maturity, and incubation time) to 1 of 7 heifers (32 bags/heifer during each run). Degradation rates were determined using a first-order kinetic model and data were analyzed with stage of maturity as a fixed effect and plot as a random effect. The DM, OM, and NFC yields increased linearly for barley and oat (P < 0.001), and increased quadratically for millet and wheat (P ≤ 0.025). Neutral detergent fiber yield increased linearly for barley (P = 0.005) and quadratically for millet, oat, and wheat (P = 0.044). There were no changes in CP yield observed for barley, millet, or oat with advancing maturity, but there was a linear increase observed for wheat (P = 0.002). The NFC concentration increased linearly for barley, millet, and oat (P < 0.001), and quadratically for wheat (P < 0.001), whereas the EDDM concentration decreased quadratically for millet, oat, and wheat (P = 0.003). The degradation rate of NDF decreased linearly with advancing maturity (P ≤ 0.014) for millet, oat, and wheat, but was not affected for barley (P = 0.13). The yield EDDM increased linearly for barley and oat (P < 0.001), and increased quadratically for millet and wheat (P ≤ 0.025). These findings suggest that harvesting whole-crop annual cereals at the hard dough and mature stages may maximize the yield of EDDM.
In western Canada, dugouts are the primary source of water for beef cattle during the summer months. Over time, drought conditions and/or direct access by grazing animals have a negative effect on water constituents and overall water quality. A study was conducted to determine the effects of improvements in water quality on cattle performance. The effect of pasture water quality on weight gain of beef cattle was assessed with 44 Hereford yearling steers over 5 years and 40 Angus cow–calf pairs over 3 years. From 1999 to 2003, cattle were allocated to 1 of 4 treatments, which comprised untreated dugout water pumped to a trough, aerated water pumped to a trough, and coagulated and chlorinated water pumped to a trough, all compared with direct access by livestock to the water source. Data were collected on livestock weight gains, water consumption, fecal parasites, environmental conditions, water chemistry, biological constituents, and forage production and quality. Water treatment by aeration or coagulation tended to improve steer weight gains (P < 0.05) over untreated water from a dugout in 3 of 5 years. Daily weight gains tended to be improved slightly by simply pumping water to a trough without treatment. Water aerated and pumped to a trough in early summer tended to produce greater (P < 0.05) weight gains in calves than those drinking directly from the dugout. The effect of treatment on improving cattle weight gains appeared to be related to improved water palatability, which increased water and feed consumption. Water chemistry and biological constituents analysed did not identify significant differences among treatments. These results suggest that improving water quality with aeration and pumping to a trough will improve weight gain 9–10% over a 90-day grazing period in most years.
Postweaning heifer development systems were evaluated at 2 locations in a 4-yr study for their effect on performance and subsequent adaptation to grazing corn residue as a pregnant heifer. In Exp. 1, heifers were blocked by BW and randomly assigned to graze winter range (WR) or graze winter range and corn residue (CR). In Exp. 2, heifers were assigned to graze winter range and corn residue (CR) or graze winter range and placed in a drylot (DL). Artificial insemination and natural mating were used at breeding on the basis of location. In Exp. 1, heifers developed on corn residue tended (P = 0.11) to have reduced ADG compared with WR heifers. Subsequently, BW at the end of the 82-d corn residue grazing period tended (P = 0.09) to be lower for CR compared with WR heifers. However, the proportion of heifers attaining puberty before the breeding season and pregnancy rates were similar (P ≥ 0.29) for CR and WR heifers. Developing heifers on winter range tended (P = 0.09) to reduce heifer development costs $36/pregnant heifer compared with CR heifers. In Exp. 2, DL heifers had greater (P < 0.01) overall ADG during development compared with CR heifers, resulting in greater (P < 0.01) prebreeding BW for DL heifers compared with CR heifers (355 vs. 322 ± 9 kg). At pregnancy diagnosis BW remained greater (P = 0.02) for DL compared with CR heifers (423 vs. 406 ± 7 kg). Corn-residue-developed heifers had increased (P = 0.03) AI conception rates compared with DL heifers (78% vs. 67% ± 6%). However, there was no difference (P ≥ 0.21) in percent pubertal before the breeding season or final pregnancy rates for CR and DL heifers. Developing heifers on corn residue reduced (P = 0.02) heifer development costs $38/pregnant heifer compared with DL-developed heifers. A subset of pregnant heifers from both experiments grazed corn residue fields in late gestation. As pregnant heifers grazing corn residue, WR heifers (Exp. 1) tended to have reduced ADG compared with CR heifers (0.34 vs. 0.43 ± 0.08 kg/d, P = 0.07). Furthermore, in Exp. 2 CR heifers had greater (0.41 vs. 0.30 ± 0.22 kg/d) ADG grazing corn residue as pregnant heifers compared with DL-developed heifers. Calving date, dystocia score, and calf birth BW were similar (P ≥ 0.15) between development systems in both experiments. There appears to be a potential learned grazing behavior for heifers developed on corn residue allowing them to better adapt to grazing corn residue as pregnant heifers compared with WR and DL heifers.
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