Dale R. ZoBell

Stockpiled Forage Kochia to Maintain Beef Cows During Winter

Abstract Extending grazing into the winter, as opposed to feeding of harvested forages, can increase the sustainability of ranching in the western US. This study was conducted to determine the economic value of grazing stockpiled forage kochia (Kochia prostrata [L.] Scrad.) and crested wheatgrass (Agropyron desertorum [Fisch. Ex Link] Schultes) during the fall and winter. Changes in cow body weight, body condition score, and ultrasound backfat were compared for late-gestation cows grazing forage kochia–crested wheatgrass pastures vs. those fed alfalfa (Medicago sativa L.) hay in drylot. The study was conducted from early November to late January for 2 consecutive years near Promontory, Utah. Forage availability and nutritional quality were monitored throughout the experiment. Cows grazing stockpiled forages did not receive any protein or energy supplements. Forage kochia comprised approximately 70% of available forage, with November crude protein content of 116 and 76 g·kg−1 in years 1 and 2, respectively. Nutritional quality declined throughout the season, presumably mostly because of removal of higher-quality forage by preferential grazing as opposed to weathering. Averaged over years, cows grazing forage kochia–grass gained body weight (19 kg), increased in body condition (0.3 points), and maintained backfat thickness, finishing well within the range considered optimum for onset of calving and return to estrus. Pasture- vs. drylot-fed cows did not differ with regard to changes in body weight or body condition score. Both treatments increased backfat in year 1, when initial backfat was less than 0.5 cm, but both treatments resulted in loss of backfat in year 2, when initial backfat was greater than 1.0 cm. Grazing was more economical, costing

Growth performance, ruminal fermentation profiles, and carcass characteristics of beef steers grazing tall fescue without or with nitrogen fertilization1

0.24·cow−1·d−1 less than feeding alfalfa hay in drylot. Forage kochia can be used on western rangelands to extend grazing into the fall and winter, thereby improving the profitability of beef production.

Ruminal fermentation, milk fatty acid profiles, and productive performance of Holstein dairy cows fed 2 different safflower seeds1

A 2-yr study was conducted to evaluate the effects of finishing beef cattle grazed on tall fescue (TF) pastures without or with N fertilization on growth performance, ruminal fermentation, and carcass characteristics. In each grazing season, 18 Angus crossbred steers were arranged in a completely randomized design with repeated measures on the following 2 treatments: TF without N fertilizer (TF–NF) and TF with N fertilizer (TF+NF). Three replicated pastures with 3 steers per replicate were assigned to each treatment. A total of 168 kg/ha N fertilizer was applied in 3 split applications at 56 kg/ha each to the TF+NF in each grazing season. Steers rotationally grazed on 0.47-ha pasture for 7 d with a 28-d rotation interval for a total of 16 wk. Body weight data and pasture forage samples were collected every 4 wk, whereas ruminal fluid was collected at wk 4, 10, and 16. After the completion of 16-wk grazing, ultrasound measurement was performed to assess carcass characteristics. In response to N fertilization, greater CP concentration was detected on TF+NF compared with TF–NF in 2011 (11.9 vs. 10.6% DM, respectively; P < 0.01). Overall ADG was greater in steers that grazed TF+NF pastures (P < 0.05) in the 2-yr grazing seasons, and tended to increase (P = 0.07) overall DMI and G:F in 2010. Regardless of N fertilization, ADG peaked between wk 4 and 8 (1.05 kg/d; P < 0.01), and then declined until wk 16. A gradual decline of G:F was noticed with progression in grazing seasons (P < 0.05). Greater total VFA concentrations were detected in ruminal fluid of steers that grazed TF+NF (P < 0.01), but a minor effect was shown on individual VFA (acetate, propionate, and butyrate) concentrations and acetate-to-propionate ratio. Ruminal ammonia-N (NH3-N) concentration increased (P < 0.01) with N fertilization, whereas NH3-N:total VFA increased (P < 0.01) with the progression of grazing seasons. Backfat thickness, ribeye area, and intramuscular fat concentration did not differ between treatments. Overall results of this study indicate that N fertilization on TF affected ruminal fermentation which positively influenced growth performances, but did not affect carcass characteristics of grazing beef steers. In addition, readily fermentable carbohydrate supplementation is needed to improve utilization of increased dietary CP due to N fertilization and consequently enhance growth performances of grazing steers.

Effects of Supplementing a Fibrolytic Feed Enzyme on the Growth Performance and Carcass Characteristics of Beef Steers1

A lactation trial was conducted to determine the effects of supplementing whole safflower seeds (SS) on ruminal fermentation, lactational performance, and milk fatty acid (FA) profiles. Nine multiparous Holstein cows (days in milk = 110 ± 20) were used in a replicated 3 × 3 Latin square design. Each period lasted 21 d, with 14 d of adaptation and 7 d of data collection. Within square, cows were randomly assigned to a sequence of 3 dietary treatments as follows: cottonseed total mixed ration (TMR; CST), conventional SS (variety S-208) TMR (CSST), and NutraSaff SS (Safflower Technologies International, Sidney, MT) TMR (NSST). Diets contained approximately 63% forage (36% alfalfa hay, 4% grass hay, and 23% corn silage) and 37% concentrate supplemented with 2% cottonseed to the CST and 3% conventional or NutraSaff SS to the CSST or the NSST, respectively. Intake of dry matter (DM) averaged 21.8 kg/d and did not differ across diets, but feeding the NSST decreased intake of neutral detergent fiber (NDF) due to lower dietary concentration of NDF in the NSST. Digestibilities of DM and nutrients were similar among treatments. No differences in yields of milk or milk components were observed in response to supplementing SS. Dietary treatments did not affect ruminal pH, total or molar proportions of ruminal volatile FA, and ammonia-N. However, cows fed SS had a higher molar proportion of isobutyrate than those fed the CST diet. Ruminal C16:0 FA concentration increased with the CST, whereas C18:1 cis-9 and C18:2 n-6 tended to increase with SS supplementation, indicating that conventional and NutraSaff SS were partially protected from microbial biohydrogenation. Supplementing SS decreased milk C16:0 concentration, whereas it increased C18:1 cis-9 and C18:1 trans-9. Milk FA C18:1 trans-11 and cis-9, trans-11 conjugated linoleic acid increased and tended to increase with feeding the NSST, respectively, but not the CSST diet. In conclusion, supplementing diets with whole SS at 3% of dietary DM can be an effective strategy of fat supplementation to lactating dairy cows without negative effects on lactational performance and milk FA profiles.

Addition of high concentration of inorganic selenium in orchardgrass (Dactylis glomerata L.) hay diet does not interfere with microbial fermentation in mixed ruminal microorganisms in continuous cultures1

The objective of this study was to determine the growth performance of growing and finishing beef steers when fed with a fibrolytic feed enzyme (FFE) in a completely randomized design. This experiment was conducted during growing and finishing periods using 60 group-penned Angus crossbred steers randomly assigned to treatments: control (no enzyme), low enzyme, and high enzyme. For the enzyme treatments, the FFE was added to the control diet at a dose of 1 or 2 g enzyme/kg DM TMR for the low-enzyme or high-enzyme treatment, respectively. Supplementing the growing diet with FFE did not affect DMI, regardless of dose rate. Body weight gain was not affected by FFE supplementation. Supplementation with FFE did not affect ADG and G:F. The overall growth performance during the finishing period was not influenced by the FFE, as was seen in the growing period. However, supplementation with FFE reduced 12th-rib fat thickness (P < 0.01) and tended to decrease the marbling score (P = 0.14) across both enzyme doses. Supplementing the beef growing and finishing diets with FFE at 1 and 2 g/kg DM TMR did not affect growth performance and had minor effects on the carcass characteristics of beef steers.

Effects of an exogenous proteolytic enzyme on growth performance of beef steers and in vitro ruminal fermentation in continuous cultures1

ABSTRACT The current literature lacks information on ruminal microbial metabolism in response to high selenium (Se) concentration in the diet. The current study was performed to investigate changes in ruminal fermentation when high concentration of Se was administered in mixed ruminal cultures in fermentors. Two mature beef cows, fitted with a rumen cannula, were grazed on tall-fescue pasture and used as donor animals for ruminal contents. Filtered ruminal contents were allowed 11 d of adaptation to diets followed by 3 d of data collection. A dual-flow continuous culture system was used in a completely randomized design (n = 4) to test 2 dietary treatments: control (no Se addition) and 50 mg/kg of Se addition. Orchardgrass hay (20 g of DM/d) containing 0.12 mg/kg of Se was added to the fermentors in 2 equal portions at 0800 and 1700 h. Selenium (sodium selenate) was added to the Se-addition treatment by gradually increasing the concentration from 2 to 50 mg/kg over the 11-d adaptation period. Culture pH averaged 6.04 and was not affected by treatment. Total VFA concentration averaged 52.2 and 55.5 mM in the control and Se treatment cultures, respectively, and addition of Se did not affect the total VFA concentration. Molar proportions of acetate and propionate did not differ because of Se addition, resulting in a similar acetate-to-propionate ratio. However, addition of Se tended to increase (P = 0.09) ammonia-N concentration and methane production (P = 0.10). Selenate-respiring microorganisms were detected by the most probable number enumeration technique in 3 of the 4 replications receiving Se. Addition of 50 mg/kg of Se in orchardgrass-hay diet had no negative effects on ruminal fermentation, as was observed in similar culture pH and VFA concentration. However, addition of Se affected microbial metabolism in the mixed cultures by increasing ammonia-N concentration and methane production. Overall data in this study suggest that the addition of Se up to 50 mg/kg would not interfere with in vitro ruminal metabolism by microbiota and that some adaptation of Se-reducing microbes may occur.

Effects of energy supplementation in pasture forages on in vitro ruminal fermentation characteristics in continuous cultures1

ABSTRACT A series of experiments was conducted to investigate the effects of adding an exogenous proteolytic enzyme (EPE) on the growth performance of beef steers fed growing and finishing diets containing 30% dried distillers grains with solubles (DDGS; Exp. 1), and results corroborated by in vitro ruminal fermentation in continuous cultures (Exp. 2). In Exp. 1, 48 Angus crossbred steers were randomly allotted to 12 pens (4 animals per pen) and assigned to 2 treatments (6 pens per treatment) in a completely randomized design: DDGS TMR (DT) without and with EPE (27 mg of azocasein hydrolyzed/min/kg DM TMR). The addition of EPE during the growing phase increased DMI (P = 0.02), but had no effects on final BW, BW change, ADG, and G:F. Adding EPE during the growing phase decreased NDF digestibility, whereas the digestibility of DM, CP, and ADF was not affected. There was a tendency for both ADG (P = 0.09) and final BW (P = 0.11) to increase during the finishing phase without affecting BW change and G:F. As opposed to the growing phase, EPE increased digestibility (P

Fatty acid composition in adipose tissue of pasture- and feedlot-finished beef steers1

ABSTRACT A dual-flow, continuous-culture system was used to assess the effects of energy supplementation with 4 pasture forages on in vitro ruminal fermentation characteristics. Twelve dietary treatments were tested in a split-plot design: energy supplementation (no concentrate, 30% ground corn, or 30% dried distilled grains with solubles) as a whole plot and pasture forages [tall fescue (TF) without N fertilizer, TF with N fertilizer (TF+NF), TF-alfalfa mixture, and TF-birdsfoot trefoil mixture (TF+BFT)] as a subplot. Three replicated runs lasted 9 d each, with 7 d for adaptation period and 2 d for data collection. The greatest total VFA and propionate concentrations (P

Effects of processed corn silage on its digestibility and production of growing beef replacement heifers

ABSTRACT Twenty-seven Angus crossbred steers were used to evaluate the effects of finishing beef cattle on pasture without or with N fertilization of the pasture versus feedlot finishing beef steers on fatty acid composition in subcutaneous adipose tissue. A completely randomized design with repeated measures was used to arrange steers into 3 treatments: grazing on tall fescue (TF) without N fertilizer (TF−NF), grazing on TF with N fertilizer (TF+NF), and feeding TMR on feedlot (FLT). For the pasture treatments, it was hypothesized that N fertilization would affect fatty acid composition of adipose tissue in pasture-fed beef steers because of its potential effects on nutrient and energy utilization. Three replicated pastures or group pens with 3 steers per replicate were assigned into each treatment. A total of 168 kg of N fertilizer per hectare was applied in 3 split applications at 56 kg/ha to the TF+NF. From May through September 2010 (total of 16 wk), pasture-finished steers were grazed on replicated 0.47-ha paddocks, while steers on the FLT were fed a finishing diet containing 76% barley grain. Subcutaneous adipose tissue biopsies were obtained on wk 4, 12, and 16. Total fat percentage in TF pasture did not differ due to N fertilization, and similar total fat concentrations were also measured between TF pasture and the FLT on wk 12 and 16. Nitrogen fertilization increased PUFA proportion (mg/100 mg of total fatty acid) in TF grass on wk 4 and 12, including C18:3 n-3 (P

Forage Kochia and Russian Wildrye Potential for Rehabilitating Gardner’s Saltbush Ecosystems Degraded by Halogeton

A study was conducted to determine effects of processing whole crop chopped corn prior to ensiling on diet digestibility and growth of beef replacement heifers. Corn silage (CS) was harvested using two identical six-row self-propelled choppers, one of which was adapted with a roller-processing unit. Corn was chopped to either 13.3 mm (unprocessed; UP) or 10.6 mm (processed; PR) theoretical length of cut (TLC) and ensiled in silage bags. Over the 56-day feedlot study, 90 growing British-cross replacement heifers were randomly assigned to UP or PR CS with three pens per treatment. The diet initially consisted on a dry matter (DM) basis of 55.4% UP or PR CS, 22.3% alfalfa hay (AH), 19.6% wheat middling (WM) and 2.7% supplement (SUPP). Whole plant particle size was estimated from three sub-samples per treatment. Whole cob fraction as a percent of total dry mass was 0.0% for PR and 6.4% for UP (P 0.05) but neutral detergent fiber (NDF) digestibility was higher in heifers fed the PR treatment (P<0.008). Processing substantially reduced the number of whole kernels in CS and increased NDF digestibility, but did not improve heifer performance on diets containing 55% of DM as CS.