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Biomedical subjects

R L Belyea

Publications and source records attributed to R L Belyea.

32 records · Page 2Linked to original sources
PubMed1988

Effects of variety and particle size upon utilization of fescue hay by lactating dairy cows and dairy heifers.

Missouri-96 and Kentucky-31 hays were chopped with a tub grinder containing screens with apertures of 31, 63, or 100 mm in diameter and fed to dairy cows or heifers. Particle sizes (geometric mean diameter) were 1218, 1486, and 1933 micron, respectively, for the 31, 63, and 100-mm treatments. In Trial 1, the six treatments were fed ad libitum to 24 lactating cows; concentrate was offered at 1 kg/2 kg of milk. Dry matter intake and NDF digestibility were greater for Kentucky-31, but there were no other effects of variety. Particle size did not affect DM intake, DM or fiber digestibility, nitrogen partition, milk yield, or milk fat percentage. Crude protein digestibility was greatest for the 63-mm particle size treatment. In trial 2, the six treatments were fed ad libitum to 24 dairy heifers. Intake was greater for the 31 than for the 100-mm treatment but was unaffected by variety. Variety and particle size did not affect DM digestibility, nitrogen utilization, or daily gain. In this study fescue hay chopped through screens having apertures ranging from 31 to 100 mm was without effect on milk yield or composition. Reducing particle size increased intake and nitrogen utilization but not DM or fiber digestibility.

Animal Feed↗
PubMed1988

Urine cup for collection of urine from cows.

A urine cup for continuous and complete collection of urine from cows was constructed from Plastisol, cotton webb strapping, Velcro Brand touch fasteners [corrected], snap-fasteners, denim patches, weather stripping, and vacuum hose. The urine cup was made from Plastisol using a heated lead mold. It was large enough to enclose a 9 cm x 6 cm area around the vulva of a cow and was attached by strapping and Velcro Brand touch fasteners [corrected] to patches glued to the rump. Urine cups were used repeatedly and provided for long-term collection of urine from cows, eliminating the need for indwelling catheters. Applications include long-term nutrient balance, radioisotope, and metabolism studies.

Animals↗
PubMed1988

Growth and nutrient digestion by dairy heifers fed semipurified diets.

Holstein heifers, which weighed an average of 154 kg, were randomly assigned to three dietary treatments in a split plot in time design. Differences in diets were fiber source: solka floc, corn cobs, and corn silage. The major source of added protein was corn gluten meal. Total collection metabolism periods were the final 7 d of each of two 30-d periods. Several heifers had simple digestive disturbances, which appeared to be related to low ruminal pH, while consuming the solka floc diet. Average daily gains were .78, .83, and 1.02 kg/d for treatments solka floc, corn cobs, and corn silage, respectively. Gains were within the range of acceptable growth standards and were higher than reports in the literature for semipurified and purified diets. Protein in corn gluten meal appeared to be utilized efficiently by the heifers for growth. The solka floc and corn cob diets are acceptable for growing dairy heifers where a low mineral content is desired but normal growth rates need to be maintained. The solka floc diet might be improved by including a buffer to help stabilize rumen pH.

Animal Nutritional Physiological Phenomena↗
PubMed1986

Body protein losses estimated by nitrogen balance and potassium-40 counting.

Body protein losses estimated from N balance were compared with those estimated by 40K counting. Six nonlactating dairy cows were fed an adequate N diet for 7 wk, a low N diet for 9 wk, and a replete N diet for 3 wk. The low N diet contained high cell wall grass hay plus ground corn, starch, and molasses. Soybean meal was added to the low N diet to increase N in the adequate N and replete N diets. Intake was measured daily. Digestibilities, N balance, and body composition (estimated by 40K counting) were determined during each dietary regimen. During low N treatment, hay dry matter intake declined 2 kg/d, and supplement increased about .5 kg/d. Dry matter digestibility was not altered by N treatment. Protein and acid detergent fiber digestibilities decreased from 40 and 36% during adequate N to 20 and 2%, respectively, during low N. Fecal and urinary N also declined when cows were fed the low N diet. By the end of repletion, total intake, fiber, and protein digestibilities as well as N partition were similar to or exceeded those during adequate N intake. Body protein (N) loss was estimated by N balance to be about 3 kg compared with 8 kg by 40K counting. Body fat losses (32 kg) were large because of low energy digestibility and intake. Seven kilograms of body fat were regained during repletion, but there was no change in body protein.

Animals↗
PubMed1986

Role of particle size and forage quality in digestion and passage by cattle and sheep.

Diminution of forage particles includes mastication, chewing, and digestion. In rumen of cattle and sheep fed all forage diets, particle size can range from 200 to over 1200 microns. Particle size reduction to about less than 1200 microns must occur before passage. Dietary particle size may influence rumen particle size, but mastication and rumination minimizes differences among diets. Ruminants expend considerable effort to move digesta. Density, cell wall percentage, osmotic pressure, and pH may affect propulsion. Dense particles may sink to the bottom and resist escape. Cell wall may reduce digestion and passage. Osmotic pressure or pH may affect digestive efficiency and rhythm of intestinal tract muscles. Chewing, exercise, physiological functions, and body size may also affect the reduction of forage particle size. More effort is necessary to chew high than low fiber diets. Young cattle (less than 225 kg) lack rumination capability and body size to process forage particles efficiently. Exercised sheep (26,400 kg-m/d) ate less forage and ruminated less than controls. Other body functions, such as lactation, appear to influence chewing patterns and rumination. These relationships are poorly understood at best and need additional intensive examination.

Animal Feed↗
PubMed1985

Utilization of chopped and long alfalfa by dairy heifers.

Two physical forms of alfalfa hay, chopped and long, were fed at maintenance and for ad libitum consumption to dairy heifers to determine effects upon digestibility and energy utilization. Ad libitum intake was associated with lower digestibility of dry matter (56 versus 58%), neutral detergent fiber (45 versus 58%), and acid detergent fiber (45 versus 52%). Energy balance was 1.77 Mcal/day at ad libitum versus .08 Mcal/day at maintenance. Dry matter intake was similar for chopped (5.4 kg/day) versus long alfalfa (5.5 kg/day). Digestibilities of dry matter, neutral detergent fiber, acid detergent fiber, and cellulose were 7 to 10 percentage units lower when heifers were fed the chopped alfalfa. Metabolizable energy intake generally reflected digestible energy intake, which was about 2 Mcal/day less for heifers consuming chopped alfalfa. Heat production was similar for the two physical forms. Consequently, heifers consuming chopped alfalfa had lower energy balance. Reducing particle size of the alfalfa resulted in lower dry matter and energy digestibility, presumably because of increased rate of passage. Increased intake to compensate for depressed energy utilization of the chopped alfalfa did not occur; effects upon animal gain could not be assessed.

Animal Feed↗
PubMed1982

Effect of environmental heat and dietary fiber on thyroid physiology of lactating cows.

Six lactating dairy cows were assigned randomly to a diet either of low fiber (30% corn silage) or of high fiber (70% corn silage). Both groups were subjected to 10 days thermoneutral (17.6 degrees C) and 10 days of environmental heat (31.2 degrees C) to determine effects of dietary fiber content and environmental heat on concentrations of thyroxine and triiodothyronine in plasma, milk, urine, and feces. During heat there were significant reductions in concentrations of thyroxine and triiodothyronine in plasma and in excretion of thyroxine and triiodothyronine in milk. Excretion of thyroxine and triiodothyronine increased in urine during heat stress, whereas concentration and excretion of thyroxine and triiodothyronine in feces decreased. Dietary fiber content had little effect upon thyroxine and triiodothyronine concentrations in plasma or excretion in milk, feces, and urine. Excretion of triiodothyronine in milk was negatively correlated with rectal temperature and positively with content in plasma. The reduction in thyroxine and triiodothyronine of plasma and the decline in excretion of thyroxine and triiodothyronine suggested that environmental heat reduced synthesis of both hormones.

Animals↗
PubMed1981

Intake, digestibility, ruminal characteristics and rate of passage of orchardgrass diets fed to sheep.

Four orchardgrass diets ranging in cell wall content from 60 to 78% were fed to sheep, and relationships among intake, digestion, passage and ruminal measurements were determined. As cell wall concentration increased, dry matter intake, digestible energy intake, dry matter digestibility and excretion rate decreased, while cell wall intake rumen volume, rumen cell wall and retention time increased. Indigestible cell wall intake was similar with each diet. It appeared that as digestible energy intake decreased, the sheep attempted to adapt by increasing ruminal ingesta volume, increasing ruminal ingesta cell wall and decreasing rate of passage; as cell wall concentration increased, indigestible cell wall limitation was manifested in decreased levels of feed and energy intake. Rate and extent of digestion appeared to be related to indigestible cell wall and appeared to be key factors in the control of cell wall turnover and feed intake.

Animal Feed↗
PubMed1980

Effect of particle size upon digestible cell wall and rate of in vitro digestion of alfalfa and orchard grass forages.

Alfalfa and orchardgrass forages chopped through a 13-mm screen were larger in particle size than were rumen ingesta samples from sheep fed the same forages. Samples of the chopped forages were ground through 1-, 4-, 8-, and 12-mm screens; particle sizes of the 8- and 12-mm ground forages were not significantly different from those of rumen ingesta samples or chopped forages. The 1- and 4-mm ground forages were significantly smaller in particle size than the 8- and 12-mm ground forages, rumen ingesta and chopped forage. Alfalfa contained less cell wall at the beginning of in vivo digestion, more cell wall residue at the end of digestion and less potentially digestible cell wall than did orchardgrass. The cell wall of alfalfa was 44% digestible, whereas that of orchardgrass was 61% digestible; particle size did not affect the amount of digestible fiber. Alfalfa ground through 1- and 4-mm screen openings had digestion rate constants that were about twice those of the 8- and 12-mm granulations (.10 less than P less than .20). Particle size did not affect rate constants of orchardgrass. These data suggest that in vitro kinetic studies based on examination of finely ground forages (1) may not reflect in vivo conditions, and (2) may depend upon the type of forage. Differences between legumes and grasses in (1) amount of digestible fiber and (2) digestion rate constants and the interaction of the above two factors with particle size and passage rate have important implications for digestibility of forage fiber.

Animal Feed↗
PubMed1980

Effect of delignification upon in vitro digestion of forage cellulose.

Orchardgrass forages harvested at two maturities (early and late) were ground through two screens (1 and 8 mm) and digested in vitro as intact forage and forage delignified by permanganate oxidation. Initial and residual cell wall, initial and residual cellulose and potentially digestible cellulose were greater in late intact forage than in the early. In the delignified forage, late cut forage had less residual cellulose than did the early, but initial and potentially digestible cellulose were similar. Particle size had less consistent and smaller effects upon cell wall and cellulose than did maturity. Cellulose of intact orchardgrass was 64% digested at 72 h vs 94% for cellulose of delignified orchardgrass. Digestion rate of cellulose was .0197 and .0220 logn units/hr for early and late cut intact forage and .0554 and .0719 logn units/hr for early and late cut delignified forage. Removal of the inhibitory effects of lignin increased the amount of digestible cellulose, increased the rate at which cellulose degraded and decreased the indigestible cellulose residue. Reduction in lignin could greatly improve forage intake and utilization at moderate levels of animal production.

Animal Feed↗
PubMed1980

Relationship of dietary selenium to selenium in plasma and milk from dairy cows.

In a 13-wk trial Holstein cows in mid-lactation were fed four diets containing natural selenium alone or supplemented with .1, .2, or .5 mg of inorganic selenium per kilogram of diet. Dietary selenium concentration averaged .334, .385, .456, and .772 mg/kg. Selenium plasma in wk 7 averaged .112 mu/ml with no differences among treatments; milk selenium ranged from .040 to .046 mu/ml and was higher in the two higher selenium diets. In wk 13 selenium in plasma and milk averaged .119 and .054 with no treatment differences. The 7 and 13 wk concentrations were higher than pretrial .084 and .033 mu/ml for plasma and milk during which time dietary selenium concentration was .254 mg/kg. Selenium concentration increased linearly from about .08 to .120 mu/ml of plasma and about .030 to .055 mu/ml of milk as intake of selenium increased from about 2 to 6 mg/day. Increase in selenium intake from 6 to 12 mg/day resulted in little change in plasma and milk selenium. Moderate concentrations of dietary selenium (.3 to .7 mg/kg) do not result in toxic amounts of selenium in milk.

Animals↗
PubMed1976

Effects of a low calcium diet on feed intake, milk production, and response to blood calcium challenge in lactating Holstein cows.

Twenty-four lactating cows were fed a normal-calcium (.75% of dry matter) diet plus free-choice dicalcium phosphate supplement for 8 wk, a low-calcium (.25% of dry matter) diet for 9 wk, and a low-calcium (.25% of dry matter) diet plus free-choice supplement for 4 wk. The low-calcium diet did not appear to affect adversely feed intake, milk production, or plasma ions. Depression of plasma calcium by sequestration with a chelating agent was less following low intake of calcium than following adequate calcium intake. Presumably, lower calcium intake increased parathyroid hormone which resulted in a larger and more responsive calcium pool immediately mobilizable. Changes in plasma phosphorus and magnesium were similar among treatments. Low calcium intake for short times apparently will not affect intake or production and may increase resistance to calcium stress such as hypocalcemia and parturient paresis.

Animal Feed↗
PubMed1975

Effects of silage diets on health, reproduction, and blood metabolites of dairy cattle.

Forty-eight Hostein dairy cows were assigned uniformly by parity and calving date to three forage treatments for three lactations. Forage treatments were corn silage (F-I), corn silage plus Hay-crop silage (-f-II), and corn silage plus hay (F-III). Records of health and reproductive data were kept to evaluate dietary effects. During the third lactation six animals in each treatment were blood-sampled on a 4-day interval from 24 days prepartum to 60 days postpartum to determine metabolites. Reproductive traits were similar among the treatment groups as were occurrences of mastitis. Corn silage and hay-crop silage cows had more ketosis than hay cows. Corn silage cows had more parturient paresis than the other two groups, and abomasal displacement occurred only in the corn silage group. There were differences in concentrations of plasma metabolites among treatments; however, they appeared to be within normal ranges, and no pathological implications were obvious. Blood pH, blood packed cell volume, blood alkaline reserve, and pH values were similar among treatment groups. Histological evaluation of hepatic and endocrine tissues revealed no treatment effects.

Abomasum↗