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Biomedical subjects

D C Clanton

Publications and source records attributed to D C Clanton.

8 recordsLinked to original sources
PubMed1992

Effects of ruminally degradable and escape protein supplements on steers grazing summer native range.

One experiment was conducted during 1989 to determine whether a deficiency exists for either ruminally degradable or escape protein in steers grazing summer native range. Increasing levels of ruminally degradable (.15, .27, and .37 kg/d) and escape protein (.07, .14, and .21 kg/d) replaced a cornstarch and molasses (energy control) supplement. Supplements were isoenergetic and fed individually to steers (.88 kg/d). No response to the degradable protein supplement (P = .15) was observed; however, a linear gain response (P less than .01) was observed in steers fed escape protein in addition to ruminally degradable protein. An in vitro study indicated that more (P less than .01) microbial protein was synthesized from the energy supplement than from the degradable protein; this finding presumably relates to the numerical decrease in weight gains observed for steers fed degradable protein supplements. Analyses of esophageal extrusa samples indicated that CP was relatively constant for the 1989 growing season compared with the 1988 growing season (P less than .05). Escape protein values differed (P less than .01) between years and among months within year. Forages that were apparently grazed in 1989 were never deficient in degradable protein. Additional gain observed from feeding escape protein would indicate that microbial protein synthesis may be insufficient to satisfy the metabolizable protein requirement, which probably limited gains by steers grazing summer native range.

Animal Feed↗
PubMed1990

Intake and digestion of low-quality meadow hay by steers and performance of cows on native range when fed protein supplements containing various levels of corn.

Two trials were conducted to evaluate the effects of corn in protein supplements fed to cattle receiving low-quality forages. In Trial 1, four ruminally cannulated steers (avg BW 500 kg) and four intact steers (avg BW 270 kg) were used in a replicated latin square to determine intake and digestibility fo a low-quality meadow hay (4.3% CP) when fed no supplement (NS), 1.12 g CP/kg BW (PS), 1.12 g CP/kg BW with corn supplying 1.98 g starch/kg BW (PLC) or 1.12 g CP/kg BW with corn supplying 3.96 g starch/kg BW (PHC). Hay DMI decreased (P = .001) and total diet DMI increased (P = .001) quadratically as supplemental corn increased. Diet DM digestibility increased (P = .004) and forage DM and hemicellulose digestibility decreased (P less than or equal to .018) quadratically as level of corn in the diet increased. In Trial 2, 135 cows received either ear corn (1.16 kg TDN and 127 g CP.hd(-1).d(-1), ear corn plus protein (1.16 kg TDN) and 290 g CP g CP.hd(-1).d(-1) or protein (.72 kg TDN and 290 g CP.hd(-1.d(-1) while grazing native Sandhills winter range for 112 d and while receiving hay (10% CP) during the following 60-d calving period. Cows that received ear corn lost (P less than .001) more weight than cows fed ear corn plus protein supplement, which lost more weight than cows fed only protein supplement (-54, -18 and 6 kg, respectively) during the 112-d winter grazing period. Cows that received ear corn and ear corn plus protein gained more (P less than .001) weight during calving and summer grazing (after supplement wa withdrawn) than protein-supplemented cows. Reproductive performance was not affected (P greater than .705) by treatments.

Animal Feed↗
PubMed1989

Intake and digestibility of low-quality meadow hay by cattle receiving various levels of whole shelled corn.

Two trials were conducted to evaluate the effects of whole shelled corn supplementation on intake and digestibility of low-quality meadow hay by cattle. In Trial 1, four ruminally cannulated steers (avg BW 418 kg) were used in a latin square design with four treatments (no corn or corn fed at .25%, .50% or .75% of BW). Hay DMI decreased (P = .002) linearly .43 g for each gram of increase in corn intake. In contrast, total diet DMI increased (P = .001) linearly as level of corn supplementation increased. Apparent DM digestibility of the diet increased (P = .026) linearly, whereas hay DM digestibility was not affected (P greater than .05) by supplemental corn, although the DM digestion coefficient for hay alone was 24% higher than for hay fed with corn at .75% of BW. Ruminal ammonia concentration and pH were not affected (P greater than .05) by treatments; however, ratio of acetate:propionate and acetate:butyrate responded (P less than or equal to .097) quadratically to increased corn supplementation. Corn supplementation resulted in a cubic (P less than or equal to .081) decrease in meadow hay NDF disappearance from nylon bags suspended in the rumen at all incubation intervals after 4 h. In Trial 2, 45 crossbred, nonlactating, pregnant cows (avg BW 474 kg) were used in a completely randomized design with three treatments (no corn, .91 and 1.81 kg corn.hd-1.d-1). Cow performance was not altered (P greater than .05) by treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Feed↗
PubMed1989

Forage intake by lactating beef cows differing in potential for milk production.

Two feeding trials (early and late lactation) were conducted to measure ad libitum forage intake by beef cows from three breed groups of similar mature weight, but with different milk production potential. Twenty-four cow-calf units, eight from each milk production level (low, medium and high) were grouped (two/pen) based on similarity of cow weight and previous weigh-suckle-weigh and calf weaning weight data. Each pair of cow-calf units was confined to separate pens and allowed ad libitum access to chopped native Sandhills meadow hay. Dry matter intake, cow and calf BW and calf milk consumption were determined. Daily DMI (kg/hd) and milk consumption showed a positive linear response (P less than .05) among low, medium and high milk-producing cows. When cow DMI was expressed as g/unit mean cow BW during the trial, both a positive linear (P less than .05) and a quadratic response (P less than .01) expressed the relationship among production levels during early and late lactation. Calf forage intake, birth weight and adjusted 181- and 205-d weaning weight had no linear or quadratic relationship (P greater than .10) to milk production levels. However, June 1 calf weight, actual calf weaning weight and calf rate of gain (birth to weaning) had a positive linear (P less than .07) relationship. Best fit regression models with DMI as the dependent variable were developed for each trial based on R2 and CV values of the potential models. The best fit model (R2 = .94, SE = .33) for early lactation included production level as a class variable with cow BW.75 and calf birth weight as independent variables. The best fit model (R2 = .92, SE = .53) for late lactation included actual weaning weight in addition to the variables used during early lactation.

Animal Feed↗