E.S. Vanzant

Effects of various supplemental starch and protein levels on ruminal fermentation and liquid passage of beef steers fed tallgrass-prairie hay

The effect of supplements containing various proportions of degradable intake protein (DIP) and starch on ruminal digestion characteristics of forage-fed beef steers was evaluated. Fluid passage rates, ruminal ammonia (N H), 3 and total volatile fatty acid (VFA) concentrations increased as the amount of supplemental DIP increased. Starch infused at .3% of BW increased molar proportion s of propionate and butyrate and decreased acetate, compared to feeding DIP alone. However, proportions of branched-chain VFA increased with DIP at all levels of starch infusion. Total digestible organic matter intake (TDOMI) was increased with each addition of DIP; however, infusing starch within a DIP level decreased TDOMI. Providing supplemental DIP is more important for improving the use of low-quality, tallgrass-prairie hay than is ruminally available starch.

Effects of supplemental degradable intake protein on intake and digestibility of forage sorghum hay

Sixteen ruminally fistulated beef steers with ad libitum access to forage sorghum hay were used to evaluate the effect of increasing level of degradable intake protein (DIP) on forage intake and digestion. Forage OM intake and total OM intake were enhanced with increasing level of DIP supplementation. Similarly, increases in total OM digestibility and total digestible OM intake (TDOMI) were evident. Compared with the negative control, TDOMI was approximately doubled at the highest level of DIP supplementation.

Influence of method of processing supplemental alfalfa on intake and utilization of dormant, bluestem-range forage by beef steers

A digestion trial was conducted to determine the effect of method of processing supplemental alfalfa on the intake and utilization of dormant, bluestem-range forage. Supplement treatments were 1) control: no supplement; 2) ground and pelleted, suncured alfalfa; 3) ground and pelleted dehydrated alfalfa; and 4) longstem alfalfa hay. Bluestem forage intake (% BW), diet digestibility, and ruminal dry matter fill 4 hours after feeding were increased (P<.10) when supplemental alfalfa was fed, compared with no supplementation. Little difference was evident among different forms of supplemental alfalfa for most of the forage utilization characteristics measured. However, a weak trend (P=.18) was observed for increased intake of bluestem forage by the steers supplemented with dehydrated alfalfa pellets compared with suncured alfalfa pellets.

Seasonal forage quality of rangelands across Kansas

The K-State Research and Extension Forage Task Force surveyed Kansas rangelands during the course of seasonal changes to enable producers and managers to better estimate the feed value of their pasture forage during particular times of the year. Kansas’ two distinct rangeland vegetation types, shortgrass and tallgrass prairie, were evaluated. Forage samples were collected monthly from two rangeland sites in each of 10 Kansas counties. Tallgrass vegetation was lowest in acid detergent fiber (ADF) and greatest in crude protein (CP) from May to July, and rapidly increased in ADF and declined in CP the rest of the season. Shortgrass vegetation was also lower in ADF and greater in CP from May to July, but changed less from early summer to the winter than did tallgrass vegetation. Degradable intake protein (DIP) was greatest for tallgrass vegetation in May. Otherwise DIP was similar between tallgrass and shortgrass except in February and March when shortgrass had greater DIP. DIP was greatest in May and June for both vegetation types and gradually declined from June to December. Undegradable intake protein (UIP) values were greater for tallgrass vegetation than for shortgrass vegetation from May through July, but all other months were similar. Seasonal forage quality is different between and within rangeland vegetation types, and identification of dominant vegetation is a key determinant in choosing appropriate animal nutritional management strategies.

Estimating the undegradable intake protein content of two forages by different commercial proteases

We evaluated the potential of several commercially available proteases for use in predicting the undegradable intake protein (UIP) concentrations o f alfalfa and prairie hay. Protease s differed in their estimates o f the rate of forage protein breakdown an d the amounts of different forage protein fractions . At least one protease appeared to yield acceptable predictions of UIP via a short-term, single time-point assay. Assays of this type deserve further consideration for commercial application.

Evaluation of the protein characteristics of four diverse grasses

Forage protein characteristics in four grasses were evaluated by the nylon bag method. All of the forages used (Bermudagrass hay, brome hay, forage sorghum hay, and prairie hay) were of relatively low quality, except the Bermudagrass, which was of average quality. The forages differed in the size of different protein fractions and in the rate and extent of protein degradation. Predicted extent of ruminal protein degradation (i.e., ruminal protein availability) was lowest for prairie hay, intermediate for Bermudagrass and forage sorghum hay, and highest for the brome hay.

Effect of increasing urea level in protein supplements on intake and digestion of low-quality tallgrass-prairie forage by beef steers

Twelve ruminally fistulated steers were used to evaluate the effect of changing the proportion of supplemental degradable intake protein (DIP) derived from urea on forage intake and digestion. Steers had ad libitum access to a low-quality tallgrass-prairie hay. Supplemental treatment groups were: 1) 0% of the supplemental DIP from urea, 2) 20% of the supplemental DIP from urea, and 3) 40% of the supplemental DIP from urea. Supplements were formulated to contain 30% CP and were fed with prairie hay once daily. Results from this study indicated that urea can replace up to 40% of the supplemental DIP without affecting forage intake and digestion.

The influence of various levels of supplemental starch and degradable intake protein on prairie hay intake and digestion by beef steers

A study was conducted to determine the effect of varying the amount of supplemental degradable intake protein (DIP) and starch on prairie hay intake and digestibility. In general, DIP increased forage intake, whereas starch decreased intake. Diet digestibility also improved with increasing DIP; however, the effect of starch on digestion depended on the level of feeding. Digestible dry matter intake (which estimates total energy input) r esponded dramatically to DIP but not to starch. These results illustrate the positive effect of DIP on forage intake and digestibility; however, supplying additional starch within a DIP level appeared to have minimal effect on altering total energy supply.

Response of pregnant beef cows toundegradable intake protein fed in excess ofthe degradable intake protein requirement

Two concurrent experiments were conducted to evaluate the effect on performance and forage intake of increasing the supply of undegradable intake protein (UIP) to pregnant beef cows already receiving sufficient degradable intake protein (DIP) to maximize forage intake. Three supplements were fed at .34% BW/day, providing .092% B W/day of DIP (level determined in previous study to maximize forage intake) and .042, .059, and .077% BW/day of UIP (low , moderate, and high UIP, respectively) . In study 1, ad libitum tallgrassprairie forage intake was measured daily from 12/1/93 to 2/10/9 4 using 18 pregnant Angus x Hereford cows. Forage intake steadily increased throughout the study, but did not vary between supplements for the first 6 weeks. However , forage intake was less during the last 4 weeks for cows offered the moderate and high UIP supplements. In study 2, 117 pregnant Angus x Hereford cows grazing dormant bluestem range were used to determine the impact of the supplements on body weight and body condition changes. Level of UIP in the supplement exerted only minimal effects on cumulative or 28-day interval changes in body weight or condition.

Influence of increasing proportion of supplemental nitrogen from urea on intake and fermentation characteristics in beef steers consuming low-quality, tallgrass-prairie forage

Five ruminally and duodenally fistulated Angus × Hereford steers were used to determine int ake and fermentation responses associated with increasing the proportion of supplemental degradable intake protein (DIP) provided by urea. Steers had free access to a dormant, tallgrass-prairie forage. The supplementa l DIP was provided by sodium caseinate and (or) urea , at a level that was determined previousl y to optimize use of a similar forage. Supplementa l DIP was balanced with corn starch to provide a final supplement of 40% crude protein. Percentages of DIP from urea were: 0, 25, 50, 75, and 100%. Supplements were given intraruminally. Increasing the percentage of urea as supplemental DIP from urea did not significantly affect forage DM intake; however, fermentation characteristics changed.