The Effect of Heat Treatment of Forages on Degradation Kinetics and Escape Protein Concentration

An in situ study was conducted to evaluate the effects of heat treatments on the degradation kinetics and escape protein concentrations of forages (alfalfa and berseem clover). Alfalfa collected at 4 and 7 weeks post-harvest and berseem clover collected at 5 and 7 weeks postharvest were freeze-dried and then heated to 100, 125, and 150o C for 2 hours. Heat treatment effects were determined by placing two bags of sample (for each treatment, maturity, and forage species for a given incubation times) into the rumen of one fistulated steer fed alfalfa hay. Bags were incubated for periods of 0 to 48 hours. Increasing levels of heat treatments of forages increased concentrations of neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent insoluble nitrogen (ADIN) and non-degradable protein (NDP), potentially degradable protein proportion (PDP), and protein escaping rumen degradation (PEP) while decreasing water soluble protein (WSP) and the rates of crude protein (CP), except immature berseem clover and cell wall (CW) degradation. PEP was greater and rate of CP degradation was lower at 100 and 150o C compared to 125o C in immature berseem clover.

The Effect of Maturity and Frost Killing of Forages on Degradation Kinetics and Escape Protein Concentration

Two consecutive in situ studies were conducted to determine the effects of maturity and frost killing of forages (alfalfa and berseem clover) on degradation kinetics and escape protein concentrations. Four maturities (3, 5, 7, and 9 weeks after second harvest) of forages collected from three locations were used to determine the effects of maturity. Four weeks after a killing frost (-2o C), berseem clover was harvested from the same locations previously sampled. To evaluate maturity, 336 DacronÒ bags containing all maturities of either alfalfa or berseem clover were placed into the rumen of two fistulated steers fed alfalfa-grass hay. Frost killing effects of berseem clover were compared with maturecut berseem clover by placing DacronÒ bags into the rumen of one fistulated steer fed alfalfa hay. Bags were incubated for periods of 0 to 48 hours. With increasing maturity, the proportion of non-degradable protein (NDP) and the rate of crude protein (CP) degradation increased in both forages. While the rate of neutral detergent fiber (NDF) degradation and potentially degradable protein proportion (PDP) increased with increasing maturity in alfalfa, the rate of NDF degradation and PDP proportion decreased and proportion of water soluble protein (WSP) increased in berseem clover. The proportion of protein escaping rumen degradation (PEP) was greater in berseem clover than alfalfa, but was not affected by maturity. Frost killing of mature berseem clover decreased WSP proportion and increased PDP proportion compared to mature berseem clover harvested live. Even though ADIN concentration was higher for frost-killed berseem clover, PEP and total escape protein concentration (CEP) was also higher for frostkilled berseem clover than mature berseem clover harvested live, due to decreases in the rate of ruminal N degradation with frost-killing.

Ruminal Microbial Protein Synthesis in Sheep Fed Forages of Varying Nutritive Values

Six wethers, fitted with ruminal and duodenal cannulae, were utilized in a 6 x 6 Latin Square metabolism trial to determine efficiency of microbial protein synthesis in the rumen of sheep fed forages with varying nutritional quality. Ground alfalfa hay, oat-berseem clover hay, and baled corn crop residues were fed at an ad libitum or limited intake level. Chromium-mordanted fiber, cobalt- EDTA, and purines were used to determine digesta flow and solid passage rate, dilution rate, and microbial protein production, respectively. Sheep fed alfalfa hay had greater organic matter (OM) intakes, and amounts of OM apparently and truly ruminally digested (g/d; P < .05) than sheep fed either oat-berseem clover or corn crop residues at the ad libitum intake level. Rates of slow solid and liquid passage, and postfeeding ruminal ammonia-nitrogen (N) and volatile fatty acids (VFA) concentrations were lower (P < .05) in sheep fed corn crop residues than those fed alfalfa or oat-berseem clover hay. Total duodenal flows (g/d) and efficiencies of ruminal synthesis (g crude protein/100 g of OM truly digested; P < .05) of microbial protein were less in sheep fed corn crop residues than in sheep fed alfalfa, and oatberseem clover ad libitum. Whereas total duodenal microbial-N flow was related to organic matter intake (OMI; r2 = .97) and OM truly digested in the rumen (OMTDR; r2 = .97), microbial efficiency was related to g of nitroge truly digested in the rumen (NTDR)/100 g of OMTDR (r2 = .82) and slow solid passage rate (r2 = .91).

Jackson County Heifer Development Project Summary

The heifer development project was a five year project conducted on the site of the former Jackson County Farm north of Andrew, Iowa, for four years and on an area producer’s farm for the fifth year. Heifers arrived around December 1 each year and the average number of heifers each year was 43 with a low of 37 and high of 47. After a 30+ day warm-up period the heifers were put on a 112-day test from early January to late April. They were fed a shelled corn and legume-grass hay ration consisting of between 13% and 14% crude protein and a range of .44 to .58 megacal/pound of NEg over the five years. During the 112-day test heifers gained 1.86, 1.78, 1.5, 1.63 and 2.2 pounds per day, respectively, for years 1992 through 1996. The actual average breeding weight was less than the target weight in three years by 5, 12 and 22 pounds and exceeded the target weight in two year by 17 and 28 pounds. Estrus synchronization used a combination of MGA feeding and Lutalyse injection. Heifers were heat detected and bred 12 hours later for a three-day period. On the fourth day, all heifers not bred were mass inseminated. Heifers then ran with the cleanup bull for 58 days. The average synchronization response rate during the project was 79%. The overall pregnancy rates based on September pregnancy averaged 92%. The five year average total cost per head for heifer development was $286.18 or about $.85 per day. Feed and pasture costs averaged 61% of the total costs.

Jackson County Heifer Development Project Update

The heifer development project took place the past four years on the site of the former Jackson County Farm north of Andrew, Iowa. Heifers arrived around December 1 with 38 heifers delivered for 1992, 44 for 1993, 46 for 1994, and 47 for 1995. After a 30+ day warm-up period, the heifers were put on a 112-day test from early January to late April. They were fed a shelled corn and legume-grass hay ration consisting of between 13% and 14% crude protein and .48, .58, .44, and .54 megacal/pound of NEg respectively for the years 1992 - 1995. During the 112-day test heifers gained 1.86, 1.78, 1.5, and 1.63 pounds per day respectively for years 1992 through 1995. The 1995 heifers averaged 853 pounds at breeding (22 pounds under target weight). This compares with previous years in which the breeding weight was less than target weight in two years by 5 and 12 pounds and exceeded the target weight in one year by 17 pounds. Estrus synchronization used a combination of MGA feeding and Lutalyse injection. Heifers were heatdetected and bred 12 hours later for a three-day period. On the fourth day, all heifers not bred were mass inseminated. Heifers then ran with the cleanup bull for 58 days. The synchronization response rate in 1995 was 83%, which compares with the three year previous average of 77%. The overall pregnancy rates based on September pregnancy exams were 94.6% in 1992, 93% in 1993, 91% in 1994, and 91.5% in 1995. Development costs for the 326 days in 1995 totaled $269.14 per heifer. This compares with the average of $286. 92 for the three previous years. The four-year average total cost per head for heifer development was $282.48, or about $.84 per day. Feed and pasture costs represented 58% of the total costs, or $.49 per day.

Evaluation of Proteferm® as a Nitrogen Supplement for Finishing Steers

Proteferm is a liquid by-product from the production of monosodium glutamate by fermentation that is 40% solids and contains 95% crude protein on a dry basis. Two trials were conducted with yearling steers to study the effects of different levels of Proteferm when added to 90% concentrate diets to replace corn and urea. Feeding Proteferm resulted in a decrease in urine pH, suggesting a metabolic acidosis that was probably caused by a negative cation–anion balance. Correcting the cation–anion imbalance resulted in an increase in feed intake and the performance of steers fed Proteferm as 1.5% of diet dry matter to be similar to the performance of control steers. Addition of sodium bicarbonate to the control diet or to the diet containing 1.5% Proteferm to produce a positive cation–anion balance did not improve performance. The results of these trials indicate that 1.5% Proteferm is the maximum that should be added to high concentrate diets fed to beef cattle without affecting performance or carcass value.

Evaluation of Bambermycins (GAINPRO®) as a Feed Additive in Receiving Rations for Beef Calves

Three-hundred-forty-eight newly weaned beef calves were used in duplicate 28-day experiments to evaluate GAINPRO®, Aureomycin, or no feed additive. Diets fed were formulated to provide 14.5% crude protein (CP) and .48 megacalorie per pound net energy (Mcal/lb. NEg) . Aureomycin reduced (P < .05) average daily gain (ADG) for the first 14 days compared to GAINPRO® or no feed additive. This effect disappeared by 28 days on feed, and ADG favored (P < .05) Aureomycin-supplemented calves compared to those given no feed additives. Calves receiving GAINPRO® fell between the two treatments for 28-day ADG.

Evaluation of Condition Scoring of Feeder Calves as a Tool for Management and Nutrition

Two experiments were conducted to evaluate the effects of body condition scores of beef calves on performance efficiency and carcass characteristics. In Experiment 1, 111 steer calves were stratified by breed and condition score (CS) and randomly allotted to 14 pens. The study was analyzed as a 2 x 3 factorial design, with two breeds (Angus and Simmental) and three initial CS (4.4, 5.1, and 5.6). In Experiment 2, 76 steer calves were allotted to six pens by CS. The resultant pens averaged 3.9, 4.5, 4.7, 5.0, 5.1, and 5.6 in CS. Calves in both studies were fed a corn-based finishing diet formulated to 13.5% crude protein. All calves were implanted with Synovex- SÒ initially and reimplanted with Revalor-SÒ. In Experiment 1, 29-day dry matter intake (lb/day) increased with CS (17.9, 18.1, and 19.1 for 4.4, 5.1, and 5.6, respectively; p < .04). Daily gain (29 days) tended to decrease with increasing CS (4.19, 3.71, and 3.26; p < .13). Days on feed decreased with increasing CS (185, 180, and 178d; p < .07). In Experiment 2, daily gains also increased with decreasing initial CS for the first 114 days (p < .05) and tended to increase overall (p < .20). In Experiment 1, calves with lower initial CS had less external fat at slaughter (.48, .53, and .61 in. for CS 4.4, 5.1, and 5.6, respectively; p < .05). This effect was also noted at slaughter (p < .10), as well as at 57 days (p < .06) and at 148 days (p < .06) as measured by real-time ultrasound. Measurements of intramuscular fat and marbling were not different in either study. These data suggest that CS of feeder calves may be a useful tool for adjusting energy requirements of calves based on body condition. Also, feeder cattle may be sorted into outcome or management groups earlier than currently practiced using body condition and/or real-time ultrasound.

Effects of Pasture Conditions in Spring on Seasonal Forage Productivity

Fifteen beef cow-calf producers in southern Iowa were selected based on locality, management level, historical date of grazing initiation and desire to participate in the project. In 1997 and 1998, all producers kept records of production and economic data using the Integrated Resource Management-Standardized Performance Analysis (IRM-SPA) records program. At the initiation of grazing on each farm in 1997 and 1998, Julian date, degree-days, cumulative precipitation, and soil moisture, phosphorus, and potassium concentrations were determined. Also determined were pH, temperature, and load-bearing capacity; and forage mass, sward height, morphology and dry matter concentration. Over the grazing season, forage production, measured both by cumulative mass and sward height, forage in vitro digestible dry matter concentration, and crude protein concentration were determined monthly. In the fall of 1996 the primary species in pastures on farms used in this project were cool-season grasses, which composed 76% of the live forage whereas legumes and weeds composed 8.3 and 15.3%, respectively. The average number of paddocks was 4.1, reflecting a low intensity rotational stocking system on most farms. The average dates of grazing initiation were May 5 and April 29 in 1997 and 1998, respectively, with standard deviations of 14.8 and 14.1 days. Because the average soil moisture of 23% was dry and did not differ between years, it seems that most producers delayed the initiation of grazing to avoid muddy conditions by initiating grazing at a nearly equal soil moisture. However, Julian date, degree-days, soil temperature and morphology index at grazing initiation were negatively related to seasonal forage production, measured as mass or sward height, in 1998. And forage mass and height at grazing initiation were negatively related to seasonal forage production, measured as sward height, in 1997. Moreover, the concentrations of digestible dry matter at the initiation of and during the grazing season and the concentrations of crude protein during the grazing season were lower than desired for optimal animal performance. Because the mean seasonal digestible dry matter concentration was negatively related to initial forage mass in 1997 and mean seasonal crude proteins concentrations were negatively related to the Julian date, degree-days, and morphology indeces in both years, it seems that delaying the initiation of grazing until pasture soils are not muddy, is limiting the quality as well as the quantity of pasture forage. In 1997, forage production and digestibility were positively related to the soil phosphorus concentration. Soil potassium concentration was positively related to forage digestibility in 1997 and forage production and crude protein concentration in 1998. Increasing the number of paddocks increased forage production, measured as sward height, in 1997, and forage digestible dry matter concentration in 1998. Increasing yields or the concentrations of digestible dry matter or crude protein of pasture forage reduced the costs of purchased feed per cow.

Effects of Chemical Composition on Forage Intake of Heifers Fed Hays of Different Species

Alfalfa, smooth bromegrass, and big bluestem hays harvested at two maturities differing by four weeks were fed at mature-to-immature hay ratios of 1:0, 2:1, 1:2, and 0:1 to yearling heifers in an experiment with a three 4 x 4 Latin square design with 14 day periods. Concentrations of in vitro digestible dry matter and crude protein were greater and concentrations of neutral detergent fiber, acid detergent fiber, and indigestible neutral detergent fiber (determined by either a manual method with a 96 hour incubation or an automated method with a 48 hour incubation) were less in alfalfa hay than in the two grass hays and in smooth bromegrass hay than in big bluestem hay. Concentrations of in vitro digestible dry matter and crude protein decreased whereas those of neutral detergent fiber, acid detergent fiber and indigestible neutral detergent fiber increased with increasing forage maturity. Consumptions of dry matter, digestible dry matter, in vitro digestible dry matter, and crude protein were greater for heifers fed alfalfa hay diets than those fed the two grasses. Consumptions of total neutral detergent fiber and indigestible neutral detergent fiber, determined by the automated method with a 48 hour incubation, were greater by heifers fed diets containing big bluestem than those fed alfalfa or smooth bromegrass diets. Consumptions of acid detergent fiber and indigestible neutral detergent fiber, determined by a manual method with a 96 hour incubation, were greater for heifers fed alfalfa or big bluestem hay diets than those of heifers fed smooth bromegrass diets. Consumption of dry matter, in vivo or in vitro digestible dry matter, crude protein, neutral detergent fiber, acid detergent fiber and automated indigestible neutral detergent fiber decreased as the mature-to-immature hay ratio decreased. Diet digestibility was not affected by forage species, but increased as the mature-toimmature hay ratio decreased. Fecal excretion of dry matter and neutral detergent fiber did not differ between forage species or mature-to-immature hay ratios. Forage dry matter intake expressed as a percentage of body weight was significantly related to the concentrations of in vitro digestible dry matter (r2=.14), crude protein (r2=.17), neutral detergent fiber (r2=.20), and manual indigestible neutral detergent fiber (r2=.18) of the hays and the concentration of digestible dry matter of the diets (r2=.43).

Evaluation of Stockpiled Berseem Clover and Brown Midrib Sorghum x Sudangrass as Supplements for Grazed Cornstalks in Beef Cow Wintering Systems

Berseem clover and oats were incorporated into a corncorn- oat/berseem clover rotation in 1994 and 1995. Two cuttings of oat-berseem clover hay were harvested during the summer before forage was allowed to stockpile for winter grazing. In 1995, a brown midrib sorghum x sudangrass hybrid was seeded into a field adjacent to a corn field. After corn grain harvest in 1994 and 1995, Charolais x Angus x Simmental cows in midgestation were allotted to replicated fields containing corn crop residues with no complementary forages at 2.5 acres/cow, or corn crop residues and stockpiled berseem clover (2:1) at 2.5 acres/cow to simultaneously graze, or to a drylot. In 1995, cows were allotted to fields containing corn crop residues and brown midrib sorghum x sudangrass (7:3) at 2.5 acres/cow. Berseem clover had greater concentrations of digestible organic matter and crude protein than corn crop residues at the initiation of grazing, but had a more rapid decrease in digestible organic matter concentration than corn crop residues. Brown midrib sorghum x sudangrass forage also had a higher initial concentration of digestible organic matter, but an equal rate of decrease in digestible organic matter concentration to corn crop residues in ungrazed areas of the field. Cows grazing berseem clover with corn crop residues had greater body condition score increases during the first half of the grazing season than cows grazing corn crop residues without complementary forages. Cows grazing corn crop residues without complementary forages required 2,786 and 1,412 less lb hay per cow than cows maintained in a drylot in 1994 and 1995. In 1994, simultaneous grazing of berseem clover with corn crop residues did not reduce hay feeding more than feeding corn crop residues alone. However, in 1995, grazing berseem clover or brown midrib sorghum x sudangrass with corn crop residues reduced the amount of hay required to maintain cows by 358 and 376 lb hay per cow compared with grazing corn crop residues without complementary forage.

Evaluation of Stockpiled Berseem Clover and Brown Midrib Sorghum x Sudangrass as Supplements for Grazed Cornstalks in Beef Cow Wintering Systems

Berseem clover and oats were incorporated into a corn-oat/berseem clover rotation in 1994-1996. Two cuttings of oat-berseem clover hay were harvested during the summer before forage was stockpiled for winter grazing. In 1995, brown midrib sorghum x sudangrass hybrid was seeded into a field adjacent to a corn field. This was repeated in 1996 with a standard sorghum x sudangrass hybrid. After corn harvest in 1994–1996, Charolais x Angus x Simmental cows and heifers in midgestation were allotted to corn crop residue, corn crop residue-berseem clover, and corn crop residue-sorghum x sudangrass fields at 2.5 acres/cow, or to a drylot. Berseem clover had greater concentration of digestible organic matter and crude protein than corn crop residues. Corn crop residue digestible organic matter concentration was lower than berseem clover and the brown midrib sorghum x sudangrass, but was higher than that of the standard sorghum x sudangrass hybrid in 1996. Cows grazing corn crop residues without complementary forages required an average of 2,374 less lb. hay per cow than cows maintained in a drylot in 1994-1996. In 1994 and 1996, simultaneous grazing of berseem clover with corn crop residues did not reduce hay feeding more than feeding corn crop residues alone, yet did significantly reduce the amount of hay needed in 1995 to maintain cows by 358 and 376 lb. hay per cow compared with grazing corn crop residues without complementary forage.

Changes in Chemical Composition and Digestion Kinetics of Stockpiled Kura Clover in Late Fall

Stockpiled kura clover samples harvested on three different winter dates were used to determine changes in chemical composition and N digestion kinetics. Kura clover was harvested from four different plots at 14 d intervals and analyzed for neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP), acid detergent insoluble nitrogen (ADIN), and in vitro digestible dry matter (IVDMD), and in situ digestion kinetics of N. Crude protein concentrations decreased, but ADIN concentrations increased with later date of harvest. Digestible N pool-size and the rate of digestion was the lowest in third-harvest kura clover. Although the proportion of protein that is soluble or nondigestible increased, proportion of protein that is potentially digestible decreased with maturity.