Leslie Aaron Stalker

Late gestation supplementation of beef cows differing in body condition score: Effects on cow and calf performance

A 2-yr study utilizing 120 mature, crossbred (Angus × Herford) cows/year, evaluated the influence of cow BCS and dried distillers grains with solubles (DDGS) supplementation during late gestation on cow performance and productivity of subsequent offspring. Treatments were arranged as a 2×2 factorial in a randomized complete block design with 2 BCS and with or without DDGS supplementation. Cows were nutritionally managed to enter the last trimester of gestation with a BCS of approximately 4 (LBCS) or 6 (HBCS) and were thereafter managed in a single herd (initial BCS were 4.4 and 5.7 for LBCS and HBCS treatments, respectively). During the last trimester, 12.7 kg/cow of low quality meadow hay (6.4% CP; DM basis) was provided each day. Supplemented cows were gathered and sorted into pens (12 pens; 5 cows/pen; 6 pens/BCS) every Monday, Wednesday, and Friday, and received the equivalent of 0.9 kg/cow daily of DDGS (31% CP; DM basis; supplement was consumed within 30 min on each supplementation day). Calf birth weight was greater for HBCS compared to LBCS (P=0.001) and for supplemented compared to nonsupplemented cows (P=0.04). Cow weight at weaning was greater for HBCS compared with LBCS (P<0.001); however, no differences were noted because of supplementation (P=0.16). Weaning weight was greater for the offspring of supplemented compared to nonsupplemented cows (P=0.02). There were no differences in postweaning calf performance (growing lot and feedlot) or carcass characteristics (P>0.05) due to treatments. Nevertheless, HBCS cows had approximately 10% more live calves at birth and at weaning (P≤0.01) compared to LBCS cows. Consequently, the total weaned calf weight per cow was 26 kg greater for HBCS compared with LBCS (P=0.004). Pregnancy rate was greater (P=0.05) for HBCS than LBCS cows (92% vs. 79%, respectively) but not affected by supplementation (P=0.94). This research demonstrates the potential consequences of not maintaining cows in adequate BCS at calving. Also, though it appears that supplementation of beef cows with DDGS during late gestation has a positive effect on weaning weight, there was no apparent developmental programming effect on feedlot performance and carcass characteristics of calves.

A meta-analysis evaluation of supplementing dried distillers grains plus solubles to cattle consuming forage-based diets 1

Data from 20 (13 pasture grazing and 7 confinement-fed) forage-based growing studies utilizing 790 steers and heifers supplemented dried distillers grains (DDGS) were analyzed using mixed models to determine the response to supplementing different levels of DDGS on gain and forage intake. Thirty-eight treatment means (442 cattle) were from grazing cattle supplemented DDGS (range: 0.00 to 1.03% BW/d). Twentyeight treatment means (348 cattle) were from confinement-fed cattle supplemented DDGS (range: 0.00 to 1.27% BW/d). Outcomes of interest were the effect of DDGS intake on forage intake (confinement studies), final BW, and ADG. In pasture grazing studies, final BW increased linearly (P < 0.01) and tended to increase quadratically (P = 0.07) with increasing DDGS supplementation. Daily gain increased linearly (P < 0.01) with increased DDGS supplementation. Results from confinement-fed studies indicate that final BW (P < 0.01) and ADG (P < 0.01) increased quadratically with increasing DDGS supplementation. Intakes measured in the confinement studies suggest that increasing DDGS supplementation increases total DMI (P < 0.01) quadratically, even though forage intake decreases (P < 0.01) quadratically with increased DDGS supplementation. Results from all studies indicate that increasing DDGS supplementation increases ADG and final BW, and supplementation of DDGS replaces some forage in forage-based diets fed to growing cattle.

Corn residue stocking rate affects cattle performance but not subsequent grain yield.

This study investigated effects of stocking rate on cattle performance, quality and quantity of corn residue, and impact of residue removal on grain yield for 5 yr at the University of Nebraska - Lincoln West Central Water Resources Field Laboratory near Brule, NE. Four removal treatments-1) no removal (control), 2) grazing at 2.5 animal unit month (AUM)/ha, 3) grazing at 5.0 AUM/ha, and 4) baling-were applied to a center pivot-irrigated corn field (53 ha). The field was divided into eight 6.6-ha paddocks to which replicated treatments were assigned. Samples of residue were collected in October and March (before and after residue removal) using ten 0.5-m quadrats per treatment replication. Residue was separated into 5 plant parts-stem, cob, leaf, husk, and grain-and analyzed for nutrient content. Esophageally fistulated cattle were used to measure diet quality. Cattle assigned to the 2.5 AUM/ha stocking rate treatment gained more BW ( < 0.01) and BCS ( < 0.01) than cattle assigned to the 5.0 AUM/ha treatment. Leaf contained the most ( < 0.01) CP and husk had the greatest ( < 0.01) in vitro OM disappearance (IVOMD) but the CP and IVOMD of individual plant parts did not differ ( > 0.69) between sampling dates. Amount of total residue was reduced ( < 0.05) by baling and both grazing treatments between October and March but was not different ( > 0.05) in control paddocks between sampling dates. As a proportion of the total residue, stem increased ( < 0.01) and husk decreased ( < 0.01) between October and March. Diet CP content was similar ( = 0.10) between sampling dates for the 2 grazing treatments but IVOMD was greater after grazing in the 2.5 AUM/ha grazing treatment ( = 0.04). Subsequent grain yields were not different ( = 0.16) across all 4 residue removal treatments. At the proper stocking rate, corn residue grazing results in acceptable animal performance without negatively impacting subsequent corn grain production.

Calving date and wintering system effects on cow and calf performance I: A systems approach to beef production in the Nebraska Sandhills 1

A 4-yr study using 217 cows/yr (3/4 Red Angus, 1/4 Simmental) evaluated effects of calving date and wintering sys

Influence of Distillers Dried Grain Supplementation Frequency on Forage Digestibility and Growth Performance of Beef Cattle

ABSTRACT Three experiments evaluated the influence of supplementation frequency of distillers dried grains plus solubles (DDGS) on forage digestibility (Exp. 1) and growth of yearling heifers (Exp. 2) and steers (Exp. 3). In Exp. 1, 6 steers (371 ± 30 kg) were used in a replicated 3 × 3 Latin square design with three 21-d periods. Treatments were DDGS fed at 16.7% of the diet (DM) either 1) daily, 2) every other day, or 3) every third day. In Exp. 2, 48 heifers (193 ± 20 kg) were fed hay and supplemented with the daily equivalent of 1.3 kg/heifer of DDGS, either 3 or 6 d/wk. In Exp. 3, 48 steers were assigned to replicated supplementation groups. Treatments were 1) hay and supplement fed 6 d/wk in a dry lot (control); 2) native winter range and supplement fed 6 d/wk; 3) native winter range and a DDGS supplement fed 6 d/wk; and 4) native winter range and the same DDGS supplement fed 3 d/wk. In Exp. 1, diet DM ( P = 0.06), OM ( P = 0.07), and hay NDF ( P = 0.03) digestibility decreased linearly as DDGS supplementation frequency decreased. In Exp. 2, heifers fed DDGS 6 d/wk gained more BW ( P = 0.01) than heifers fed 3 d/wk. In Exp. 3, steers fed the control diet, native winter range and supplement fed 6 d/wk, and native winter range and DDGS supplement fed 6 d/wk performed similarly, but performance was decreased when steers were fed native winter range and the DDGS supplement 3 d/wk. Improved animal growth may result from more frequent supplementation of DDGS when fed in excess of 15% of the diet.

TECHNICAl NOTE: Estimating beef-cattle forage demand: Evaluating the animal unit concept

The objective of this experiment was to evaluate the effect of BW and physiological status of a beef animal on forage intake. The experiment was repeated over 2 yr with 6 replications of 3 treatments per year: cow-calf pair (CCP, BW = 629 kg), nonlactating cow (NLC, BW = 503 kg), and yearling steer (YS, BW = 305 kg). The CCP was treated as one unit, with the sum of cow BW and calf BW comprising CCP BW. Calves averaged 42 d of age and 73 kg at the start of the experiment each year. Animals were housed in individual pens and fed grass hay harvested from subirrigated meadow (11% CP) in quantities sufficient for ad libitum intake. Intake of DM, OM, DM that disappeared in vitro, and NDF were greatest (P 0.05) from each other. When expressed as a percentage of metabolic BW (BW0.75), intake of DM, OM, DM that disappeared in vitro, and NDF were greatest (P < 0.01) for CCP, intermediate for NLC, and least for YS. Results indicate that intake differences among cattle of different physiological states should be considered when calculating forage demand for stocking rate or feeding purposes.

Calving date and wintering system effects on cow and calf performance II: Economic analysis 1

Data from a 4-yr study involving 217 cows/yr (3/4 Red Angus, 1/4 Simmental) were used to compare net returns among 5 cow/calf production systems: 1) March (Mar) calving cows wintered on native range, 2) Mar calving cows wintered on corn residue, 3) June (Jun) calving cows wintered on native range, 4) Jun calving cows wintered on corn residue, and 5) August (Aug) calving cows wintered on corn residue. Steers born in Mar entered the feedlot at weaning (November; calf-fed). Steers and heifers born in Jun and Aug were divided equally into 2 postweaning management treatments. Half entered the feedlot immediately after weaning (May, calf-fed) and the other half grazed subirrigated meadow and entered the feedlot as yearlings (September to October). Average USDA reported monthly prices for the yr 2007 to 2010 were used to value both inputs and outputs. Prices utilized were at time of purchase for feed ingredients and replacement cows and time of sale for cattle. Costs were not different (P = 0.81) among calving dates, but net returns were greatest (P 0.21) calf feedlot performance. Steers generated greater (P < 0.01) net returns than heifers when ownership was retained. Net returns were greater (P < 0.02) for calf-fed compared with yearling cattle when purchased at weaning and sold on a marketing-grid basis. Purchasing and finishing yearlings was not profitable. Net returns vary by calving date, wintering system, ownership length, postweaning management system, and calf sex.

The effects of supplementing dried distillers grains to steers grazing cool-season meadow1

Two summer experiments were conducted with 28 (BW = 291 ± 22 kg; Exp. 1) and 48 (BW = 280 ± 22 kg; Exp. 2) steers to determine the effect of supplementing dried distillers grains plus solubles (DDGS) on growth when grazing subirrigated Sandhills meadow. Steers were stratified by BW and assigned randomly to a treatment. In Exp. 1, there were 2 treatments: nonsupplemented or 0.6% of BW (1.75 kg) DDGS supplementation daily. In Exp. 2, there were 3 treatments: 0, 0.6 (1.68 kg), or 1.2% of BW (3.36 kg) DDGS supplementation daily. In both experiments, steers were individually supplemented for the duration of the study (Exp. 1 = 92 d; Exp. 2 = 91 d). Both experiments were analyzed as completely randomized designs with individual steer as the experimental unit. In Exp. 1, ending BW (P = 0.52) and ADG (P = 0.16) were not different. In Exp. 2, ADG (P 0.06). However, in Exp. 2, supplementing DDGS to steers grazing subirrigated Sandhills meadow increased carcass weight (P = 0.02) with increasing level of DDGS supplementation. In Exp. 2, supplementing DDGS during summer grazing did not affect QG or YG. Results from Exp. 2 indicate that supplementing DDGS at levels greater than 0.6% of BW during summer meadow grazing increases ADG, with BW maintained through finishing.

Using measurable physical characteristics to forecast beef heifer maturity: the identification of a maturity index.

A target BW is often used to estimate sexual maturity in beef heifers. The target BW, a percentage of mature BW, is generally an average for the breed, herd, or both. Heifer development is done in groups or herds, and not all heifers respond similarly to the same development regimen. Generally, heifers fed at a higher plane of nutrition gain more BW and tend to have increased pregnancy rates, but this usually increases feed costs. Therefore, determining when increased feed costs exceed the economic gains resulting from greater conception rates is critical and requires the inclusion of economic information and relationships. This research focused on the individual heifer as the decision point, and identification of the individual heifer target BW was based on clearly defined biological relationships observed before breeding. These relationships were captured in a maturity index (MI) identified through a series of steps and guided by current, accepted knowledge of heifer growth and development. Using an in-sample mean absolute percent error comparison, it was determined the MI was more accurate than the current group or herd methods in forecasting actual maturity and target BW. Maturity index demonstrated the flexibility in achieving similar maturities with beef heifers of varying characteristics using alternative nutritional programs. The MI was also the only significant predictor of first pregnancy. These results allow for more precision in determining sexual maturity and probability of first pregnancy in beef heifers and serve as the basis for future studies in determining profit differences among heifers.

Bioeconomic Factors of Beef Heifer Maturity to Consider when Establishing Criteria to Optimally Select and/or Retain Herd Replacements

Understanding the biology of heifer maturity and its relationship to calving difficulty and subsequent breeding success is a vital step in building a bioeconomic model to identify optimal production and profitability. A limited dependent variable probit model is used to quantify the responses among heifer maturities, measured by a maturity index (MI), on dystocia and second pregnancy. The MI account for heifer age, birth BW, prebreeding BW, nutrition level, and dam size and age and is found to be inversely related to dystocia occurrence. On average there is a 2.2% increase in the probability of dystocia with every 1 point drop in the MI between the MI scores of 50 and 70. Statistically, MI does not directly alter second pregnancy rate; however, dystocia does. The presence of dystocia reduced second pregnancy rates by 10.67%. Using the probability of dystocia predicted from the MI in the sample, it is found that on average, every 1 point increase in MI added 0.62% to the probability of the occurrence of second pregnancy over the range represented by the data. Relationships among MI, dystocia, and second pregnancy are nonlinear and exhibit diminishing marginal effects. These relationships indicate optimal production and profitability occur at varying maturities, which are altered by animal type, economic environment, production system, and management regime. With these captured relationships, any single group of heifers may be ranked by profitability given their physical characteristics and the applicable production, management, and economic conditions.