Distribution of micronutrients in Arborg oat (Avena sativa L.) using synchrotron X-ray fluorescence imaging.

It is important to know the mineral distribution in cereal grains for nutritional improvement or genetic biofortification. Distributions and intensities of micro-elements (Mn, Fe, Cu, and Zn) and macro-elements (P, S, K and Ca) in Arborg oat were investigated using synchrotron-based on X-ray fluorescence imaging (XFI). Arborg oat provided by the Crop Development Center (CDC, Aaron Beattie) of the University of Saskatchewan for 2D X-ray fluorescence scans were measured at the BioXAS-Imaging beamline at the Canadian Light Source. The results show that the Ca and Mn were mainly localized in the aleurone layer and scutellum. P, K, Fe, Cu, and Zn were mainly accumulated in the aleurone layer and embryo. Particularly the intensities of P, K, Cu, and Zn in the scutellum were higher compared to other areas. S was also distributed in each tissue and its abundance in the sub-aleurone was the highest. In addition, the intensities of S and Cu were highest in the nucellar projection of the crease region. All these elements were also found in the pericarp but they were at lower levels than other tissues. Overall, the details of these experimental results can provide important information for micronutrient biofortification and processing strategies on oat through elemental mapping in Arborg oat.

Effects of alternate day supplementation at two levels of energy on intake, rumen fermentation, and digestibility of beef heifers fed cool-season perennial grass hay.

A study was conducted to evaluate the effects of supplementing energy daily vs. on alternate days at levels that were 1.5 and 2 times the daily amount on DMI, rumen fermentation parameters, and apparent total tract digestibility of beef heifers fed grass hay. Four cannulated Hereford heifers (339 ± 11 kg) were randomly assigned over 4 periods to a 4 × 4 Latin square design. Heifers were fed a cool-season perennial grass (CSPG) hay (10% CP and 42% ADF) and supplemented with a pelleted feed formulated to provide 3.2 Mcal/kg of DE. Treatments consisted of a nonsupplemented control (CON) and 3 supplemented treatments where the supplement was offered daily at 0.6% BW (DLY) or on alternate days at 0.9% BW (LA) and 1.2% BW (HA). Heifers fed DLY had lower ( ≤ 0.04) CSPG hay DMI (7.1 vs. 8.1 kg/d) and mean ruminal pH (6.65 vs. 6.75) and greater ( < 0.01) total short-chain fatty acid (SCFA; 77.1 vs. 69.2 m) and NH-N (4.6 vs. 3.4 mg/dL) concentrations in ruminal fluid than CON heifers. The concentration of ruminal NH-N for LA (5.8 mg/dL) was greater ( < 0.01) than for DLY. Total tract DM digestibility was greater for DLY (52.5%; ≤ 0.03) than for CON (44.2%) and LA (49.7%), whereas no effects were found ( ≥ 0.11) for DLY vs. HA. When data was analyzed for days when LA and HA were supplemented, hay DMI was greater ( < 0.05) for DLY (7.3 kg/d) vs. HA (6.0 kg/d) but not different ( = 0.16) vs. LA (6.4 kg/d), mean ruminal pH of DLY (6.64) was greater vs. HA (6.59; = 0.04) and tended to be greater vs. LA (6.60; < 0.09), and total SCFA concentration of DLY (77.9 m) was lower ( < 0.01) vs. HA (88.2 m) and tended ( = 0.08) to be lower vs. LA (84.0 m). On days when LA and HA were not supplemented, hay DMI was not different ( ≥ 0.48) for DLY vs. LA and HA, mean ruminal pH was greater ( ≤ 0.03) for LA (6.79) and HA (6.85) compared with DLY (6.67), and total SCFA concentration of DLY (76.2 m) was not different ( = 0.15) vs. LA (67.5 m) but greater ( = 0.03) vs. HA (62.0 m). These results show that reducing the amount of supplement fed on alternate supplementation programs from 2 to 1.5 times the amount of daily programs can minimize the negative effects on rumen fermentation and forage DMI.

Effect of maturity at harvest for whole-crop barley and oat on dry matter intake, sorting, and digestibility when fed to beef cattle.

The objectives were to evaluate the effect of harvest maturity of whole-crop oat (Study 1) and whole-crop barley (Study 2) on forage intake and sorting, ruminal fermentation, ruminal digestibility, and total tract digestibility when fed to beef heifers. In Study 1, 3 ruminally cannulated heifers (417 ± 5 kg) were used in a 3 × 3 Latin square design with 24-d periods. Whole-crop oat forage harvested at the late milk (LMILK), hard dough (HD), or ripe (RP) stages was fed for ad libitum intake and heifers were supplemented (1% of BW) with alfalfa pellets, barley grain, canola meal, and a mineral and vitamin pellet. Maturity at harvest for whole-crop oat did not affect ( ≥ 0.058) forage intake, DE intake, amount of forage refused, ruminal short-chain fatty acid concentration, or digestibility of DM, OM, NDF, and ADF. Ruminal starch digestibility decreased ( < 0.001) from 92.6% at the LMILK stage to 90.0% at the RP stage, with total tract starch digestibility decreasing ( = 0.043) from 95.8% at the LMILK stage to 94.8% at the RP stage. Ruminal CP digestibility was reduced at the HD stage compared with the LMILK and RP stages ( < 0.001). Mean ruminal pH was greatest for the LMILK stage (6.36; = 0.003) compared with the HD and RP stages (6.30 and 6.28, respectively). In Study 2, 6 ruminally cannulated heifers (273 ± 16 kg) were used in a replicated 3 × 3 Latin square design with 24-d periods. Dietary treatments included ad libitum access to whole-crop barley harvested at the LMILK, HD, or RP stage and a constant rate (0.8% BW) of supplement containing alfalfa pellets, barley grain, canola meal, and a mineral and vitamin pellet. Dry matter intake, ruminal content mass, and feeding behavior were not affected by harvest maturity ( ≥ 0.16). There was a decrease in total tract digestibility of DM, OM, and NDF observed at the HD stage compared with the LMILK and RP stages ( ≤ 0.004). Ruminal NDF digestibility decreased from 69.7% at the LMILK stage to 54.4% at the HD stage and 54.9% at the RP stage ( = 0.001), whereas ruminal ADF digestibility decreased from 70.0% at the LMILK stage to 44.4% at the HD stage and 42.5% at the RP stage ( = 0.002). Minimum and mean ruminal pH were least for the LMILK stage, intermediate at the RP stage, and greatest at the HD stage ( = 0.016 and = 0.031, respectively). These data suggest that despite reductions in ruminal digestibility of NDF and ADF with advancing maturity, harvesting whole-crop oat and barley forage at the HD and RP stages of maturity did not negatively affect DMI, fermentation characteristics, or DE relative to whole-crop cereal forage harvested at the LMILK stage.

Effect of development system on growth and reproductive performance of beef heifers.

Reproductive performance was evaluated in beef heifers born over a 2-yr period to determine the effects of target breeding weight (TBW) and development system (SYS) on growth and subsequent reproductive efficiency. Spring-born Angus heifers (253 ± 0.7 kg) were randomly allocated over 2 consecutive yr (yr 1, n = 80; yr 2, n = 96) to be developed to either 55% (350 kg) of mature BW (moderate gain, MG) or 62% (395 kg) of mature BW (high gain, HG). Each MG and HG group was further assigned to 1 of 2 replicated systems: (1) bale graze bromegrass-alfalfa round bales in field paddocks (BG) or (2) fed bromegrass-alfalfa round bales in drylot pens (DL). Heifers were fed a diet of bromegrass-alfalfa hay (56.9% TDN; 9.8% CP) and barley grain supplement (85.1% TDN; 12.3% CP). After the 202-d development period, heifers were exposed to bulls for a 63-d breeding season. Target BW × SYS interactions were not detected for any measured parameters. During the winter development period, MG heifers had lower (P = 0.01) ADG than HG heifers and MG heifers had lighter (P = 0.01) BW at breeding. The proportion of heifers attaining puberty by 14.5 mo of age was less (P = 0.05) in MG (20 ± 4%) than HG heifers (52 ± 3%). From the end of the 202-d development period to pregnancy diagnosis, ADG was greater (P = 0.04) in MG heifers than HG heifers (0.83 vs. 0.71 kg/d). First-calf pregnancy rates were 86 and 88% for MG and HG heifers, respectively (P = 0.41). Second- and third-calf pregnancy rates of cows, developed in either a MG or HG system as heifers, were not different (P = 0.74; 94.7 vs. 95.9% and 93.8 vs. 93.9%, respectively). Economic analysis revealed a $58 reduced development cost for heifers developed to 55% compared with 62% of mature BW without a loss in reproductive performance.

Effect of beef heifer development system on average daily gain, reproduction, and adaptation to corn residue during first pregnancy.

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.

Effect of maturity at harvest on yield, chemical composition, and in situ degradability for annual cereals used for swath grazing.

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.

Nutrient export in run-off from an in-field cattle overwintering site in East-Central Saskatchewan.

Wintering cattle directly in the field creates potential concerns with water quality, as nutrients added from urine and fecal material over the winter can end up in runoff water, ground water and soil. In 2008/2009 an experiment was conducted to observe the effect of in-field winter feeding of cows on the nutrients in spring snowmelt run-off water. Low temperatures give little opportunity for organic N, urea and ammonium added in the urine and fecal matter to convert to nitrate, resulting in nitrate-N concentrations in snowmelt run-off water that were similar in the control and winter fed areas. Orthophosphate-P and ammonium-N concentrations were significantly elevated in run-off from the winter feed treatment basins compared to the controls. Surface soil sampled in the spring from the winter feeding site had higher soluble nitrate while soluble forms of phosphorus in the soil were lower compared to the fall soil samples. Caution should be used when utilizing in-field winter feeding systems so that the runoff water does not reach sensitive water bodies.