D.N. Schutz

Fibrous and Nonfibrous Carbohydrate Supplementation to Ruminants Grazing Forage from Small Grain Crops

Animal performance, N balance, and forage digestibility effects of fibrous (beet pulp) and nonfibrous (corn) carbohydrate supplementation to ruminants grazing small-grain forages was studied. Similar supplements were used in 3 studies: no supplement (NS), cracked corn (CN), and beet pulp (BP) at 0.5% BW. The effect of supplementation on ADG of yearling heifers (n = 48, BW = 267 ± 22 kg) grazing triticale (CP = 20 ± 1.2%) or wheat (CP = 27 ± 8.1%) was investigated in Exp. 1. Diet digestion and N metabolism by lambs (n = 12, BW = 36 ± 3.7 kg) consuming fresh triticale forage were studied in Exp. 2. The effect of supplementation on IVDMD of triticale forage was investigated in Exp. 3. In Exp. 1, neither supplement (P = 0.76) nor crop grazed (P = 0.64) affected ADG of heifers. In Exp. 2, BP improved N retention (g/d; P = 0.03), NDF, and ADF digestion (P = 0.01) when compared with NS and CN. Treatment BP improved DM digestion compared with NS (P = 0.05) and tended to improve DM digestion compared with CN. In Exp. 3, rumen pH was lower in BP and CN as compared with NS (P < 0.01), and IVDMD was lower (P < 0.01) in treatment CN as compared with NS and BP. Fibrous carbohydrate supplementation to ruminants grazing triticale forage improved rumen bioavailability of nutrients. Correspondingly, supplementation with high carbohydrate showed no benefits in terms of N retention, ADF, or NDF digestion and decreased IVDMD. Neither supplement affected animal performance when animals on high-quality small-grain forage were experiencing compensatory gain.

Trace Mineral Supplementation in the Presence of Antagonists on Growth Performance, Health, and Carcass Characteristics of Transport-Stressed Calves

Crossbred steer calves (n = 64) were used in a 2 × 2 factorial arrangement to evaluate two levels of organic trace minerals and two levels of inorganic trace minerals. Calves were fed 28 d on the ranch in two pens of eight head per treatment before a simulated transport stress. After being loaded, hauled 129 km, unloaded with an overnight stand without feed and water, and reloaded, they were shipped to the Colorado State University (CSU) research feedyard in Fort Collins and placed in 64 individual pens. Calves fed the organic low level and inorganic high level trace minerals gained better (P<0.05) the first 28 d than did calves fed the organic high level or inorganic low level trace minerals. Overall growth performance was not influenced by trace mineral types or levels. Longissimus area was greater (P<0.05) for calves fed the low level organic trace minerals compared with that for calves fed the low level inorganic trace minerals. Eosinophils (d 28) were higher (P<0.05) for calves fed the organic high level trace minerals compared with calves fed inorganic low level trace minerals. Infectious bovine rhinotracheitis (IBR) and parainfluenza (PI3) titers were not influenced by trace minerals. Red blood cells and packed cell volume were higher (P<0.05) for calves fed low level trace minerals regardless of trace mineral type. Liver Co was increased (P<0.05) at the 28-d sampling when inorganic trace minerals were fed. Liver Co was highest (P<0.05) at the 168- d sampling for calves fed low level inorganic trace minerals followed by calves fed organic high level trace minerals. Liver Fe was lower (P<0.05) in calves at the d-168 sampling when organic trace minerals were fed. Liver Zn was elevated (P<0.05) by d 28 by feeding the inorganic low level trace minerals, and by d-168, liver Zn was higher (P<0.05) for calves fed the low levels of trace minerals. Initial growth performance was maintained by either supplementing organic trace minerals or elevating dietary inorganic trace minerals when confronted with high dietary Fe, S, or Mo.

Reducing Annual Cow Cost by Grazing Windrowed Millet

The objective was to determine whether grazing millet stored in windrows is a viable alternative to baling and feeding hay to beef cows. Sixty spring-calving heifers (458 kg, 5.9 BCS) were randomly allotted to windrow grazing or bale feeding to determine whether performance would differ between treatments. Research was conducted from November 5, 1997 to January 8, 1998. Millet was planted in early July and harvested in early September. Two fields were paired into similarly yielding strips, which were either baled or left as windrows. Small square bales from the baled strips were weighed to estimate forage amounts in the windrows of similarly yielding strips. Field 1 (19.7 ha) was divided into six sections, three baled and three left as windrows. Field 2 (2.1 ha) was divided into one baled section and one section left as windrows. Treatments were: 1) windrow grazing with forage allocation controlled to 13.2 kg·heifer−1·d−1 by moving a temporary fence daily, and 2) daily bale feeding of 13.2 kg·heifer−1·d−1. Heifer weight and BCS were measured at the beginning, d 28, d 56, and the end of the study. Weight or BCS change was not different for any time period (P>0.10). Forage samples were collected every 2 wk for analysis. Differences in forage nutrient composition were found based on storage method. Overall, similar cow performance was attained, whereas the costs of baling and feeding hay were eliminated by grazing the windrows.

Phosphorus and Vitamin D in Beef Finishing Diets

Abstract Two hundred eighty-three steer calves (mean BW = 290 ± 6 kg) were used to evaluate the effects of feeding two levels each of phosphorus and vitamin D on growth performance and carcass characteristics. The experimental design was a 2 × 2 factorial arrangement of a randomized block design with approximately 71 steers per treatment. Steers were randomly assigned to one of four treatment groups. Each group consisted of six pens of 11 or 12 steers each. The four treatments were 1) Low P:low vitamin D (0.24% and 0 IU/kg, respectively) 2) Low P:high vitamin D (0.24% and 5,364 IU/ kg, respectively) 3) High P:low vitamin D (0.35% and 0 IU/kg, respectively) and 4) High P:high vitamin D (0.35% and 5,364 IU/kg, respectively). Starting diets contained 65% whole corn and increased to a final 89.9% whole corn finishing diet over a 4r-wk period. Overall DMI, ADG, and feed efficiency were not affected by supplementing with phosphorus and/or vitamin D in finishing diets. Off-test BW and hot carcass weight were numerically heavier for cattle supplemented with P and vitamin D. Supplementing P and/ or vitamin D to finishing calves had no significant benefit on growth performance or carcass characteristics.

Comparison of Alfalfa Hay and Distillers Dried Grains with Solubles, Alone or in Combination with Cull Beans, as Protein Sources for Beef Cows Grazing Native Winter Range

Abstract A grazing study was conducted at the Eastern Colorado Research Center (ECRC) to evaluate the use of locally available protein sources as supplements for beef cows grazing native winter range. The four treatments were as follows: 1) alfalfa hay to supply 182 g/d CP (Alfalfa); 2) a mixture of alfalfa hay and cull Great Northern Beans to each supply 91 g/d CP (Alfalfa/Beans); 3) distillers dried grains to supply 182 g/d CP (DDG); and 4) a mixture of DDG and cull Great Northern Beans to each supply 91 g/d CP (DDG/Beans). Pregnant, multiparous, spring calving crossbred cows (n = 112; 566 ± 59 kg) were randomly assigned to one of four treatments within one of two replicates. Supplemental CP was increased to 273 g/d ca. 60 d before calving. Cow BW change was affected by treatment (P 0.05) by treatment. Feeding cull Great Northern Beans to supply one-half of the supplemental CP reduced feed costs with little effect on subsequent cow performance. In this study, DDG was a less desirable source of supplemental protein because of higher cost and a lower percentage of degradable intake protein (DIP).

Effects of Salt Level on Growth Performance, Carcass Characteristics, and Manure Salinity of Finishing Beef Steers

Abstract Two hundred ninety-six British and Charolais crossbred beef steers (average BW = 305 ± 20.4 kg) were fed for 163 d at the Eastern Colorado Research Center in a randomized block design to evaluate effects of four dietary levels of salt (NaCl) on growth performance, cost of gain, morbidity/mortality, carcass characteristics and manure nutrient content. Calves were stratified by breed, randomized by BW, and assigned to one of four supplemental NaCl treatments (6 pens per treatment; containing of 11 to 13 head/ pen): 0.0, 0.125, 0.25% or block salt. Average daily feed intake, ADG, feed efficiency, and feed cost of BW gain were not affected (P>0.05) by dietary salt level. Neither mortality nor morbidity was influenced by dietary salt level. Dressing percent and hot carcass weight tended to decrease (P=0.08) linearly as salt supplementation increased. As dietary NaCl increased, concentrations of Na and Mg increased linearly (P

Effects of Dietary Phosphorus and Microbial Phytase1 Level on Beef Finishing Performance

Two experiments were conducted to evaluate the effect of feeding microbial phytase on P availability and feedlot performance of beef steers fed a whole corn-based diet. In Experiment 1, six crossbreed steers were used in a replicated 3 x 3 Latin square design. Steers were paired according to BW, and each pair was assigned to one of three treatment groups: 1) 0 FTU phytase [the quantity of phytase needed to hydrolyze 1 μM of inorganic P/min (37.2˚C and pH 5.5)]; 2) 250 FTU phytase; and 3) 500 FTU phytase. Treatments were rotated so that each pair of steers received each treatment for a 20-d period. During the last 5 d of each rotation period, steers were placed in metabolism stalls, and feed and feces were collected for mineral analyses. Apparent digestibilities for P, Ca, Mg, and Cu responded quadratically (P<0.05) as phytase level increased from 0 to 500 FTU. There were no differences in fecal mineral content (DM basis) or Zn apparent digestibility among treatments. In Experiment 2, 288 steers were used in a completely randomized experimental design to evaluate the effects of P and microbial phytase level on feedlot performance, carcass data, and apparent mineral availability. Steers were assigned to one of four treatment gruaps: 1) 0.35% dietary P and 0 FTU phytase, 2) no supplemental dietary P and 0 FTU phytase 3) no supplemental dietary P and 200 FTU phytase, and 4) no supplemental dietary P and 400 FTU phytase. Diets without supplemental dietary P averaged 0.30% P. Each treatment group consisted of six pens of 11 or 12 steers each. Steers from two pens of each treatment were used to assess the apparent digestibility of P, Ca, Mg, Cu, and Zn. Chromic oxide was used as a digestion marker and was fed, in a pellet, to steers in each pen for 17 d. During the last 3 d of each period, feed and feces were collected. There were no significant differences observed among treatments for feedlot performance or slaughter data. Fecal P percentage for steers receiving the 0.35% P and 0 FTU phytase treatment was significantly greater than that for steers receiving the other treatments. Apparent digestibility of Ca and P responded linearly and quadratically (P<0.05) as phytase level increased from 0 to 400 FTU. Magnesium, Cu, and Zn apparent digestibility responded linearly (P<0.10) as phytase level increased. These experiments suggest that supplementing microbial phytase enhanced mineral apparent digestibility in ruminants and that supplementing P did not improve feedlot performance.

Influence of Supplementation on Winter Performance, Forage Utilization, and Digesta Kinetics of Beef Cows

Supplements to winter forage were evaluated in a grazing trial with 99 mature gestating-lactating cows and in a second study with 4 ruminally cannulated cows fed harvested 4.9% CP native hay. The grazing cows were supplemented with 1) low level [LL, .54 kg cottonseed meal (CSM)], 2) positive control (PC, 1.06 kg CSM), 3) alfalfa hay (AH, 2.27 kg), 4) wheat middlings (WM, 2.78 kg), 5) CSM plus beet pulp (CSM + BP, .54 kg CSM + 2.08 kg BP). The cannulated cows were supplemented with control (C), 5% CSM (CSM), CSM + 15% BP (15 BP), and CSM + 30% BP (30 BP) in a 4 × 4 Latin square. Grazing trial daily gestation weight change was: .00, .26, .24, .18 and .65 kg/d for treatments 1, 2, 3, 4, and 5, respectively. Calf birth weights, calving percentage, milk production, and rebreeding rate were not affected by treatments. Estimated daily forage DM intake was lower (P .05) for C, CSM, and 15 BP. Ruminal fluid dilution rate, volume, and turnover time were not affected (P>.05) by supplementation. Rate of passage and in situ hay DM disappearance was faster (P<.05) for supplemented treatments than for the control. Cottonseed meal and 15 BP appeared to be better protein supplements than AH or WM for weight gain in gestating wintering beef cows.

Potassium Level and Wintering Cow Performance1

Eighty crossbred gestating cows were randomly assigned to one of four treatments that provided the following levels of supplemental K: 1) 1.37, 2) 3.58, 3) 8.52, and 4) 12.23% supplemental K, respectively, in a cottonseed meal (CSM)-based range cube. Treatments 2, 3, and 4 included KCI as the source of additional K. Cows were gathered from the same dormant winter pasture three times per week, individually stalled, and fed their respective supplements. A CSM-based range cube was fed to provide .18 kg crude protein per head per day during gestation. During the approximate 104-d gestation period, cows fed the 12.23% K supplement gained significantly faster than cows fed any of the other supplements. Cows fed the low level of KCI (3.58% K) lost more weight during gestation than cows fed either no KCI (1.37% K) or 8.52% K in the supplement. Cow condition score change mirrored weight gain change. Weight change during lactation, calf average daily gain, and reproductive performance was not significantly affected by supplemental K level. Potassium supplemented at 12.23% in the protein supplement during the precalving period appeared to produce beneficial weight gain for gestating cows grazing sand hills native range during the winter.

Feeding Time and Finishing Heifer Performance

Abstract One hundred forty-four crossbred heifers were used in a randomized block design with two treatments: 1) cattle fed at 0800 and 2) cattle fed at 1500. Heifers were fed once per day only. Time of feeding did not affect feed intake, average daily gain, or feed efficiency by the end of the 139-d trial. Heifers fed in the morning had significantly better quality grade than those fed in the afternoon.