R. O. Myer

Intake, digestibility, and nitrogen retention by sheep supplemented with warm-season legume haylages or soybean meal

The high cost of commercial supplements necessitates evaluation of alternatives for ruminant livestock fed poor quality warm-season grasses. This study determined how supplementing bahiagrass haylage (Paspalum notatum Flügge cv. Tifton 9) with soybean [Glycine max (L.) Merr.] meal or warm-season legume haylages affected the performance of lambs. Forty-two Dorper x Katadhin lambs (27.5 +/- 5 kg) were fed for ad libitum intake of bahiagrass haylage (67.8% NDF, 9.6% CP) alone (control) or supplemented with soybean meal (18.8% NDF, 51.4% CP) or haylages of annual peanut [Arachis hypogaea (L.) cv. Florida MDR98; 39.6% NDF, 18.7% CP], cowpea [Vigna unguiculata (L.) Walp. cv. Iron clay; 44.1% NDF, 16.0% CP], perennial peanut (Arachis glabrata Benth. cv. Florigraze; 40.0% NDF, 15.8% CP), or pigeonpea [Cajanus cajan (L.) Millsp. cv. GA-2; 65.0% NDF, 13.7% CP]. Haylages were harvested at the optimal maturity for maximizing yield and nutritive value, wilted to 45% DM, baled, wrapped in polyethylene plastic, and ensiled for 180 d. Legumes were fed at 50% of the dietary DM, and soybean meal was fed at 8% of the dietary DM to match the average CP concentration (12.8%) of legume haylage-supplemented diets. Lambs were fed each diet for a 14-d adaptation period and a 7-d data collection period. Each diet was fed to 7 lambs in period 1 and 4 lambs in period 2. Pigeonpea haylage supplementation decreased (P < 0.01) DM and OM intake and digestibility vs. controls. Other legume haylages increased (P < 0.05) DM and OM intake vs. controls; however, only soybean meal supplementation increased (P = 0.01) DM digestibility. All supplements decreased (P = 0.05) NDF digestibility. Except for pigeonpea haylage, all supplements increased (P < 0.01) N intake, digestibility, and retention, and the responses were greatest (P = 0.04) with soybean meal supplementation. Microbial N synthesis was reduced (P = 0.02) by pigeonpea haylage supplementation, but unaffected (P = 0.05) by other supplements. Efficiency of microbial protein synthesis was unaffected (P = 0.05) by diet. Ruminal ammonia concentration was increased (P = 0.01) by all supplements, but only soybean meal and annual peanut haylage increased (P < 0.03) plasma urea-N concentrations. Perennial peanut, annual peanut, and cowpea haylages are promising protein supplements for growing lambs.

Effect of breed composition on phenotypic residual feed intake and growth in Angus, Brahman, and Angus × Brahman crossbred cattle

The influence of additive and nonadditive genetic effects and temperament on 4 postweaning feed intake and growth traits was evaluated in a group of 581 bull, heifer, and steer calves born in 3 Florida herds in 2006 and 2007. Calves had breed compositions ranging from 100% Angus (A) to 100% Brahman (B). They were randomly allocated to 24 pens each year by herd (Brooksville, Gainesville, Marianna, FL), sire group (A, 3/4 A 1/4 B, Brangus, 1/2 A 1/2 B, 1/4 A 3/4 B, and B), and sex (bull, heifer, and steer) in a GrowSafe automated feeding facility at Marianna. Calves were fed a concentrate diet during the 21-d adjustment and the 70-d trial periods. Individual feed intakes were recorded daily, and BW, chute scores, and exit velocities were recorded every 2 wk. Traits were phenotypic daily residual feed intake (RFI), mean daily feed intake (DFI), mean daily feed conversion ratio (FCR), and postweaning BW gain. Phenotypic RFI was computed as the difference between actual and expected feed intakes. Calves were assigned to 3 RFI groups: high (RFI greater than 0.9 kg of DM/d), low (RFI less than -0.9 kg of DM/d), and medium (RFI between mean +/- 0.9 kg of DM/d; SD = 1.8 kg of DM/d). The mixed model included the fixed effects of contemporary group (herd-year-pen), RFI group (except when trait was RFI), age of dam, sex of calf, age of calf, B fraction of calf, heterozygosity of calf, mean chute score, and mean exit velocity. Brahman fraction and heterozygosity of calf were nested within sex of calf for RFI and within RFI group for DFI, FCR, and postweaning BW gain. Random effects were sire and residual. Feed efficiency tended to improve (decreased RFI) as the B fraction increased. However, calves required larger amounts of feed per kilogram of BW gain (larger FCR) as the B fraction increased. Postweaning BW gain tended to decrease as the B fraction increased. Temperament traits were unimportant for all traits except exit velocity for DFI, suggesting perhaps a lack of variation for temperament traits in this herd, or that calves became accustomed to the level of handling pre- and postweaning, thus decreasing behavioral differences among them.

Digestibility and nutrient retention of perennial peanut and bermudagrass hays for mature horses1

Mature horses were used to determine apparent DM, OM, NDF, and CP digestibility values of 2 bermudagrass (BG; Cynodon dactylon) hays, Coastal (CB) and Tifton 85 (T85), and Florigraze perennial peanut (PP; Arachis glabrata) hay. In addition, N, Ca, and P balances were determined in horses fed those hays. Five mature Thoroughbred geldings and 1 Quarter Horse gelding (mean initial BW = 542 +/- 37 kg) were used (5 horses for the last period) in a 3 x 3 repeated Latin square design, with 2 horses per hay and 3 adjustment and collection periods. Horses were randomly assigned to pairs and the initial hay to be fed. Each period consisted of a 10-d adjustment phase, followed by a 4-d total fecal and urine collection phase. Horses were fed at 1.5 (period 1), 1.7 (period 2), or 2% (period 3) of their BW daily (DM basis). The 2 BG were grown under similar conditions, with CB and T85 being cut at 4 and 5 wk of regrowth, respectively, and PP being of a late first cutting. The compositions (DM basis) of PP, CB, and T85, respectively, were 93, 94, and 93% DM; 92, 94, and 94% OM; 46, 73, and 77% NDF; 34, 37, and 42% ADF; 11, 10, and 8% CP; 1.10, 0.28, 0.27% Ca; and 0.19, 0.15, and 0.19% P, respectively. Least squares means (pooled SE) for apparent digestibility of PP, CB, and T85, respectively, were 65, 53, and 52% (1) DM digestibility; 67, 53, and 52% (1) OM digestibility; 44, 50, and 46% (4) NDF digestibility; and 66, 60, and 57% (1) CP digestibility. Digestibility values of DM and OM were greater (P < 0.001) for PP than for the BG. Digestibility of CP was greater (P = 0.001) for PP than for CB or T85, with no difference (P = 0.37) between PP and BG hays in NDF digestibility. There were no differences between CB and T85 for DM digestibility (P = 0.67), OM digestibility (P = 0.59), CP digestibility (P = 0.11), and NDF digestibility (P = 0.48). Nitrogen (P = 0.01) and P balances (P = 0.04) were greater for PP than BG hays, whereas N balance of CB was greater (P = 0.01) than that of T85. There were no differences among all hays in Ca balance (P = 0.54) and between the BG in P balance (P = 0.34). Results indicated that PP, CB, and T85 are suitable forages for horses.

Mineral Concentrations of Cool Season Pasture Forages in North Florida During the Winter-Spring Grazing Season: II. Trace Minerals

ABSTRACT Trace mineral concentrations of annual cool season pasture forages grazed by growing beef cattle during late fall-winter-spring grazing season were evaluated during two experimental cool season grazing studies, each lasting two years at the North Florida Research and Education Center (NFREC), Marianna, Florida. Eight 1.32 ha fenced pastures or paddocks were divided into two groups of pasture land preparation/planting methods, four pastures for the sod seeding treatments (SS) and four for the prepared seedbed treatments (PS). Two different pasture forages, small grains, (rye/oats mix) with or without ryegrass for the first two years (Study 1); and oats with ryegrass or ryegrass only for the last two years (Study 2) were planted in these pasture lands. Each of the four forage, type, and cultivation combination treatments was assigned to two pastures each year, thereby giving two replicates per pasture treatment per year. Forage samples were collected at the start of pasture grazing and twice monthly thereafter until the end of grazing season, pooled by month, and analyzed for copper (Cu), iron (Fe), zinc (Zn), manganese (Mn), cobalt (Co), molybdenum (Mo), and selenium (Se). Liver biopsies and blood plasma samples were collected from the tester cattle only during the spring of year two of Study 2. Liver was analyzed for Cu, Fe, Mn, Co, Mo, and Se and plasma for Cu, Fe, Zn, and Se. Forage trace mineral concentrations were found to differ by month in Cu (P < 0.01), Fe and Zn (P < 0.0001) in both studies, and with Mn (P < 0.0001) in Study 2 only. Pasture forage type effects on Cu (P < 0.05), Fe and Zn (P < 0.01), and Se (P < 0.05) and forage type by month interactions on Cu and Mn (P < 0.0001), and Zn (P < 0.05) were observed in Study 2. Forage concentrations of Cu, Zn, Mn, and Mo in Study 1 and Mn, Mo, and Se in Study 2 were affected (P < 0.05) by pasture land preparation/planting methods in that these minerals were found to be lower from forages of sod-seeded treatments than from those of prepared seedbed treatments. Forage Cu concentrations were lower than the minimum requirements (10 ppm, DM) for beef cattle among months in both studies. Oats-ryegrass pastures of Study 2 had surprisingly low Fe concentrations (P < 0.01) in all months of the winter-spring grazing season. Cobalt, Mn, Mo, and Se did not vary much month to month during the winter-spring grazing months. All mean forage Se concentrations were lower than the requirements (0.10 ppm, DM) for grazing beef cattle. There were no differences (P > 0.05) in mean Se values between the two studies. Liver Cu, Fe, Co, and Se concentrations were sufficient to indicate adequate status of these minerals in tester animals from both forage types. Liver concentrations of Mn and Mo were slightly low, indicating a low status or these minerals. Plasma concentrations of Cu, Fe, Se, and Zn were all above the recommended concentrations for beef cattle. In conclusion, trace minerals deficient in North Florida during the cool season were Cu, Co, and Se, and a special consideration should be given to include adequate amounts while supplementing the mineral mixtures to growing beef cattle since forage samples reflected deficient concentrations of these minerals.

Mineral Concentrations of Cool Season Pasture Forages in North Florida During Winter-Spring Grazing Season. I. Macrominerals and Forage Organic Constituents

ABSTRACT Two experimental late fall-winter-spring grazing studies, each lasting two years, were conducted at the North Florida Research and Education Center (NFREC), Marianna, Florida to evaluate the organic constituents and macromineral concentrations of annual cool season pasture forages grazed by growing beef cattle. Eight 1.32 ha fenced pastures or paddocks were divided into two pasture land preparation/planting methods, four pastures for the sod seeding treatments and four for the prepared seedbed treatments. These pastures were planted with two different forage combinations: rye/oats mix with or without ryegrass for the first two years (Study 1), and oats with ryegrass or ryegrass only for the last two years (Study 2). Each of the four forage/land preparation combination treatments was assigned to two pastures each year, thereby giving two replicates per year. Forage samples were collected at the start of grazing and twice monthly thereafter until the end of grazing season for each year, pooled by month, and were analyzed for calcium (Ca), phosphorus (P), sodium (Na), potassium (K), magnesium (Mg), dry matter (DM) yield, crude protein (CP), and in vitro organic matter digestibility (IVOMD). Blood plasma samples were also collected from the tester cattle during the spring season of year 2 of Study 2 and were analyzed for Ca, P, and Mg. Month differences were observed in forage concentrations of P and K (P < 0.0001), and Mg (P < 0.05) in both studies, Ca (P < 0.01) in Study 1 only, and Na (P < 0.05) only in Study 2. Year affected P, K, and Mg concentrations in Study 1 and Ca, P, and Na concentrations in Study 2. In Study 2, forage type by month interactions on Ca, K, and Mg concentrations were noticed (P < 0.01). Forage Ca was lower (P < 0.05) than the critical level for all months from the oat plus ryegrass pastures, and for early winter months and late spring months from ryegrass only pasture. Forage Na concentrations were consistently low throughout the grazing season and unaffected by forage type or land cultivation methods used in both studies. Low Mg concentrations of both forage types in Study 2 (also with high K concentrations) were indicative of a potential risk of grass tetany (hypomagnesemia) for grazing ruminants. Forage DM yields were highly variable with fluctuations among the experimental months and were found to be highest in the spring months, with decreasing yields towards the end of the grazing season in both studies (P < 0.0001). The CP concentrations were greater than the required levels and both CP and IVOMD decreased gradually by month in both studies (P < 0.0001). Normal blood plasma concentrations of Ca and P obtained were indicative of a good overall status of these minerals in the animals body. Plasma Mg concentrations were slightly above the critical level for cattle from both forage types. In summary, the macrominerals most likely to be deficient in North Florida during the cool season would be Ca, Na, and Mg. Special attention should be given to supplementation of Mg since forages reflected a marginal deficiency of this mineral and high K concentrations were found.

Crystalline Amino Acid Supplementation of Grain Sorghum-Based Low Protein Diets for Growing-Finishing Pigs

Abstract Myer, R.O. and Gorbet, D.W. 2004. Crystalline amino acid supplementation of grain sorghum-based low protein diets for growing-finishing pigs. J. Appl. Anim. Res., 25: 85–90. A study was conducted to evaluate the effectiveness of crystalline lysine, threonine, methionine and tryptophan supplementation of grain sorghum based, low protein diets for growing and finishing pigs (from 31 to 114 kg avg. body wt.). Three similar trials, each with 60 crossbred pigs were done and each involved a comparison of nutritionally adequate grain sorghum-based diets formulated with 1) soybean meal (47%) as the supplemental source of amino acids (control) or with 2) L-lysine HCl, L-threonine, DL-methionine and L-tryptophan plus enough soybean meal to meet the requirements of the other amino acids. Overall, dietary treatment had no effect (P>0.10) on average daily gain, average daily feed intake, feed conversion efficiency, average loin area, backfat thickness or estimated carcass lean percentage. Overall average daily lean gain, however, was lower (P<0.10) for pigs fed the low protein, amino acid supplemented diets compared to pigs fed the control diet. Results indicated that the diet crude protein concentration can be reduced substantially upon amino acid supplementation with no detrimental effect on pig growth performance, however, there was some evidence of decreased lean gain.

YIELD AND MINERAL CONCENTRATIONS OF SOUTHEASTERN UNITED STATES OAT CULTIVARS USED FOR FORAGE

A shift in oat (Avena sativa L.) production from grain to forage (hay and grazing) is occurring in the southeastern USA. However, most available cultivars were developed for improved grain production, rather than forage yield. We field tested several standard and new oat releases over 2 years, using repeated clippings to determine forage yield, nutrient uptake, and the potential to match plant nutrients with cattle mineral dietary needs. There were no differences in total annual forage yield among the tested cultivars within years but there was a difference between years. Forage tissue phosphorus (P), magnesium (Mg), and calcium (Ca) were sufficient, potassium (K), sulfur (S), and manganese (Mn) were excessive, and iron (Fe), copper (Cu), and zinc (Zn) were occasionally or frequently deficient to meet daily cattle dietary mineral needs. Sulfur, Cu, Fe, Zn, and Mn may be the most challenging to regulate in U.S. Coastal Plain soils at concentrations that satisfy both, oat and cattle nutritional requirements.

Influence of Feeding Growing-Finishing Pigs Triticale, Wheat or Maize Based Diets on Resulting Carcass Composition, and on Taste and Quality Characteristics of Pork

A study was conducted to determine the effect of feeding triticale (X Triticosecale Wittmack), soft red winter wheat (Triticum aestivum) or maize (Zea mays L.) based diets to growing-finishing pigs (25 to 100 kg) on resulting carcass composition, and on taste and quality of pork. Dietary grain source did not influence (P >.05) carcass lean content or quality characteristics of the longissimus muscle, such as amount of marbling, muscle texture, firmness or color. Slightly lower levels of total (P .10) due to dimly grain source. The feeding of triticale based diets resulted in small changes in carcass fat composition, however, there was no evidence that the taste of broiled loin chops was different from the taste of broiled loin chops from pigs fed maize based diets.

Effects of Annual Cool-Season Forage on Bahiagrass Production in Silvopastures

Interest in silvopastoral systems revolves around developing sustainable agriculture that increase food, forage, and fiber production without causing environmental degradation. Limited resource farmers are looking for alternative agricultural systems with possibilities for diversifying their farm products. We evaluated the effects of tree configurations and annual cool-season forage species combinations on the yield and nutritive value of ‘Argentine’ bahiagrass (Paspalum notatum Flügge.) forage in three tree configurations: double-row sets of trees with 15 m wide forage alleys (double-row), fourth row conventionally thinned stand (random-thinned), and open pasture, which acted as a control. A mid-rotation loblolly pine (Pinus taeda L.) was thinned in the summer of 2002 and a stand of Argentine bahiagrass was established in 2003. Cool-season forage varieties that were overseeded into bahiagrass in late fall grew in the winter-spring period. Cool-season forages included ‘Jumbo’ ryegrass (Lolium multiflorum Lam.), ‘Dixie’ crimson clover (Trifolium incarnatum L.), and ‘Cherokee’ red clover (Trifolium pretense L.). The tree configurations reduced dry matter (DM) yield of bahiagrass by 29% and 22% in the randomly-thinned and double-row (silvopastures) treatments, respectively when compared with open pasture. Generally, no differences were found between the two silvopastures. Although effects of cool-season forage production caused reductions in bahiagrass yields in the first summer harvest month (July), no subsequent yield differences were recorded in the following months. While the bahiagrass in open pasture occasionally had greater in vitro organic matter digestibility (IVOMD) than the silvopastures, the double-row tree spacing resulted in greater crude protein (CP) concentrations in the bahiagrass than that grown in open pasture. Bahiagrass digestibility and CP concentration from ryegrass–crimson–red clovers treatment plots were greater than other cool-season forage combinations (ryegrass and ryegrass–crimson clover). Bahiagrass intercropped with annual cool-season forage treatment plots had greater P concentrations compared with bahiagrass alone. This study revealed the feasibility of converting a mid-rotation loblolly pine stand into productive silvopastoral systems that generally support bahiagrass production after cool-season forage production in the winter-spring period. An improved understanding of the tradeoffs between improved silvopastures and depressed intercrop growth, as well as management options to forage production, will aid farmers design systems to improve yield and nutritive value of their pastures.

Synthetic Amino Acid Supplementation of Triticale and Wheat Based Diets for Growing-Finishing Pigs

Dietary supplementation of feed grade synthetic amino acids may be more advantageous for diets based on triticale (X Triticosecale Wittmack) or soft red winter wheat (Triticum aestiuum) than maize (Zea mays L.) for growing and fmishing pigs (25 to 109 kg). Four trials, involving 190 pigs, were conducted to evaluate the effectiveness of supplementation of triticale and wheat based diets with synthetic lysine and threonine for growing and finishing pigs. Substantial replacement of supplemental protein (soybean meal) with synthetic lysine and threonine did not affect pig growth or carcass lean content (P>.10). In fact, complete or nearly complete replacement of soybean meal occurred for finishing pig (55 to 109 kg) diets formulated with triticale.