J.T. Green

Performance of lactating dairy cows fed varying levels of total mixed ration and pasture

Two, 8-week experiments, each using 30 lactating Holstein cows, were conducted to examine performance of animals offered combinations of total mixed ration (TMR) and high-quality pasture. Experiment 1 was initiated in mid October 2004 and Experiment 2 was initiated in late March 2005. Cows were assigned to either a 100% TMR diet (100:00, no access to pasture) or one of the following three formulated partial mixed rations (PMR) targeted at (1) 85% TMR and 15% pasture, (2) 70% TMR and 30% pasture and (3) 55% TMR and 45% pasture. Based on actual TMR and pasture intake, the dietary TMR and pasture proportions of the three PMR in Experiment 1 were 79% TMR and 21% pasture (79:21), 68% TMR and 32% pasture (68:32), and 59% TMR and 41% pasture (59:41), respectively. Corresponding proportions in Experiment 2 were 89% TMR and 11% pasture (89:11), 79% TMR and 21% pasture (79:21) and 65% TMR and 35% pasture (65:35), respectively. Reducing the proportion of TMR in the diets increased pasture consumption of cows on all PMR, but reduced total dry matter intake compared with cows on 100:00. An increase in forage from pasture increased the concentration of conjugated linoleic acids and decreased the concentration of saturated fatty acids in milk. Although milk and milk protein yields from cows grazing spring pastures (Experiment 2) increased with increasing intakes of TMR, a partial mixed ration that was composed of 41% pasture grazed in the fall (Experiment 1) resulted in a similar overall lactation performance with increased feed efficiency compared to an all-TMR ration.

Seasonal Activity and Species Composition of Dung Beetles (Coleoptera: Scarabaeidae and Geotrupidae) Inhabiting Cattle Pastures in North Carolina

Abstract Species composition and seasonal distribution of dung beetles were studied on dairy and beef cattle pastures in North Carolina. Study sites included a dairy located in the piedmont region (North Carolina Department of Agriculture Piedmont Research Station, Salisbury, NC) and a combined dairy/beef facility in the coastal plain (North Carolina Department of Agriculture Center for Environmental Farming Systems, Goldsboro, NC). Dung beetles were trapped in cattle pastures from March 2002 through September 2003 by using dung-baited pitfall traps. Trapping yielded 4,111 beetles representing 14 species from the piedmont dairy, including Aphodius prodromus Brahm, a new record for North Carolina. Totals of 57,026 beetles representing 28 species and 28,857 beetles representing 26 species were trapped from the dairy unit and beef unit in the coastal plain site, respectively. Onthophagus gazella (F.), a second new record for North Carolina, was collected from the coastal plain. Beetles common to all collection sites include Aphodius erraticus (L.), Aphodius fimetarius (L.), Aphodius granarius (L.), Aphodius pseudolividus Balthasar, Onthophagus taurus Schreber, Onthophagus hecate hecate Panzer, and Onthophagus pennsylvanicus Harold. The introduced beetle O. taurus dominated the dung beetle population, accounting for >50% of the total beetles caught at either site. Beetle activity was greatest from March until November, with activity declining during the winter. Nine exotic species in the genera Onthophagus and Aphodius represented nearly 95% of the beetles trapped.

Performance of growing cattle grazing stockpiled Jesup tall fescue with varying endophyte status.

The objective of this study was to evaluate the performance of growing cattle when intensively grazing stockpiled endophyte-infected (E+), endophyte-free (E-), and nontoxic endophyte-infected (EN) tall fescue during the winter. The experiment was conducted over 5 consecutive winters. In each year, plots (1 ha each, 4 per treatment) were harvested for hay in August, fertilized in September, and forage was allowed to accumulate until grazing was initiated in early December. Each year, 48 Angus-cross tester cattle (4 per plot) were given a daily allotment of forage, under strip-grazing (frontal grazing) management, with a target residual height of 5 cm. Steers were used the first year, and heifers were used in subsequent years. The grazing periods for determination of pasture ADG were 86 d (yr 1), 70 d (yr 2), 86 d (yr 3), 72 d (yr 4), and 56 d (yr 5). Pasture ADG of cattle did not differ among treatments (P = 0.13) and were 0.51, 0.59, and 0.56 kg/d (SEM 0.03) for E+, E-, and EN, respectively. Serum prolactin concentrations of heifers grazing E+ were less (P < 0.05) than those grazing E- and EN during all years except yr 2. In yr 2, E+ and E- did not differ (P = 0.11). Serum prolactin of heifers grazing E- and EN did not differ (P > 0.20) except in yr 4. During yr 4, serum prolactin of heifers grazing E- was greater (P = 0.05) than that of heifers grazing EN. Serum urea-N concentrations (SUN) tended to differ among treatments (P = 0.10) and there was a treatment x year interaction (P = 0.05). During yr 1 through 3, SUN did not differ (P > 0.15) among treatments. However, as the stands aged, E- had a greater invasion of other plant species, which increased the CP content of the sward, thus causing heifers grazing E- during yr 5 to have greater (P < 0.01) SUN than heifers grazing E+ and EN, which did not differ (P = 0.89). Forage disappearance (DM basis) did not differ (P = 0.75) among treatments and was 4.7, 4.7, and 5.0 kg/animal daily (SEM 0.27) for E+, E-, and EN, respectively. Body weight gain per hectare was greater (P = 0.04) for E+ (257 kg) than for E- (220 kg) or EN (228 kg). In most years, animal grazing days on E+ were greater than those on E- or EN. However, in yr 5, animal grazing days did not differ (P > 0.20) among treatments. The use of stockpiled E+ as a source of low-cost winter feed is a viable option for producers, whereas grazing of EN may be more beneficial during the spring and fall, when more severe negative effects of ergot alkaloids have been observed.

Effects of feeding strategy on milk production, reproduction, pasture utilization, and economics of autumn-calving dairy cows in eastern North Carolina.

A balance among stocking rate (SR), pasture management, and supplementary feeding is required to optimize overall farm performance and profitability in pasture-based dairying. Beginning in September 2003, a seasonal, autumn-calving, pasture-based farming system was established to address the effects of feeding strategy (FS; i.e., a unique combination of stocking and supplementation rate) on productive, reproductive, and economic performance of lactating herds over 3 yr. Eighty lactating cows (1/3 Holsteins, 1/3 Jerseys, and 1/3 crosses of those breeds) were randomly assigned to either a lesser stocking, lesser supplementation group [LSR; 2.2 cows/ha, 6.3 kg of dry matter (DM) of a corn-based concentrate consumed daily, n=40] or a greater stocking, greater supplementation group (HSR; 3.3 cows/ha, 9.2 kg of DM of a corn-based concentrate consumed daily, n=40). Pasture/forage crop rotations included annual ryegrass and sorghum-Sudan (50%), annual ryegrass and bermudagrass (20%), and a tall fescue-white clover pasture (30%). Pre- and postgrazing herbage mass values and grazing intervals (3,347±255.8 kg of DM/ha, 1,861±160.6 kg of DM/ha, 23.6±1.9 d) did not differ between FS. The nutritive value of fresh and conserved forages was similar between feeding strategies, except for acid detergent fiber in freshly grazed bermudagrass (29.6 vs. 26.3% of DM for LSR and HSR, respectively). Cows on HSR tended to spend more time on an adjacent feeding area where conserved forages were offered (85 vs. 61 d/yr) as opposed to grazing paddocks (204 vs. 228 d/yr). Lactation performance was greater for HSR; cows on HSR produced 10.8% more milk fat and 6.3% more milk protein than cows on LSR. Holstein cows produced the greatest amounts of mature-equivalent milk, but did not differ from crossbred cows in terms of energy-corrected milk, and mature-equivalent fat and protein yields. Reproductive efficiency did not differ among feeding strategy, but breed differences were observed; conception rates at first and all services, as well as pregnancy rates, were greater for Jersey and crossbred cows compared with Holsteins. The greater stocking rate required additional supplemental concentrate and time away from grazing paddocks, but reproductive efficiency was similar and overall lactation performance was greater. The greater stocking rate resulted in increased productivity and greater income over feed costs per unit of land.

Visual Reference Guide for Estimating Legume Content in Pastures

As the prices of nitrogen fertilizers rise, there is increased incentive to grow legumes for fixing nitrogen and improving forage quality in pastures and hay meadows. From a management perspective, it is important for managers to be able to estimate legume content in the stand. In research, clipping and hand separation is the standard method for measuring legume content. However, this method is impractical for farm managers. Another option is visual appraisal of the percentage surface covered by legumes. The objective of this photo reference guide is to provide a tool that pasture managers can use to assess legume content as it is related to legume cover. For each photo, the area within the quadrat was clipped and hand separated to determine the actual legume content. These photos represent a range of legume content across two ranges of forage mass. By using these photos to help estimate legume content, forage managers should be able to increase the accuracy of their visual estimate of legume content in pastures and aftermath meadows. IntroductIon There are advantages to growing legumes with the grasses in pastures and hay fields. These include providing nitrogen for plant growth and increasing forage quality, thereby reducing fertilizer cost and enhancing animal performance (Blaser et al., 1969; Blaser and Colleagues, 1986; Rayburn et al., 2006). Legume content in pastures is a dynamic characteristic that is dependent on weather, management, nitrogen accumulation in the soil, pests, and the legume and grass species present. During dry weather, pastures may be grazed closely, allowing white clover to increase and red clover seed to germinate and establish. Proper lime and fertilizer management is essential for legume production. Most clovers grow best when the soil pH is above 6.0 and soil-test phosphorous and potassium are high. When the soil-nitrogen supply is low, as for a newly planted forage stand in a crop Published in Forage and Grazinglands DOI 10.2134/FG-2011-0176-DG