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Biomedical subjects

C J Sniffen

Publications and source records attributed to C J Sniffen.

51 records · Page 3Linked to original sources
PubMed1984

Production responses of dairy cows fed diets supplemented with ammonium salts of iso C-4 and C-5 acids.

A three-university study examined effects of ammonium salts of volatile fatty acids on dairy cows for a full lactation cycle. Objectives were a) to determine the most efficacious amount and ratio of two components, ammonium salts of C-5 acids and ammonium isobutyrate, and b) to compare responses of this optimum blend with the control in a response surface design. This design tested six blends of the two components defined by the center point and the five points of an equilateral pentagon from which response surfaces would be computed and a control. Each treatment consisted of 23 cows for a total of 161 multiparous Holstein cows. All cows were fed corn silage for ad libitum consumption, 1.8 kg of urea-mineral-vitamin-premix plus supplement based on corn grain and corn gluten meal according to milk production. Response surfaces, based on milk yield, defined an optimum blend composed of 61 g ammonium salts of C-5 acids plus 28 g ammonium isobutyrate per cow per day equivalent to 120 g aqueous blend (74% solids). The optimum blend was similar to the center point blend. Cows receiving the center point blend peaked higher and produced more milk, 4% fat-corrected milk, milk protein, and total solids than control cows. For the first trimester of lactation, milk yields for control and center point blend were 28.6 and 31.8 kg. The 305-day milk, 4% fat-corrected milk yields, and dry matter intakes (kg) were: control 20.5, 19.7, 17.3; center point blend 23.2, 21.6, 17.5. Increased milk production was associated with improved feed utilization. No effect on health or reproduction was observed.

Animal Feed↗
PubMed1984

Epidemiology of parturient paresis: predisposing factors with emphasis on dry cow feeding and management.

Dry cow feeding and management were examined for predisposing factors for parturient paresis in 1,983 Holstein cows from New York Dairy Herd Improvement Cooperative records, monthly technician visits to 31 farms, and questionnaires. Variables were estimated transmitting ability, season of calving, lactation number, parturient paresis, estimated potential hours per day of exercise, and estimated nutrient intakes (protein, calcium, phosphorus, and energy) during the preceding dry period. Nutrient intakes were estimated by farmers for the average dry cow (season dependent) in their herd for the early (greater than or equal to 3 wk prepartum) and late portions of the dry period. Intakes were percentages of National Research Council requirements for a 550 kg dry cow in the last 2 mo of gestation. Nutrient intakes were coded by ranking the herds by percentage of each requirement. Codes represented the approximate lower third, middle third, and top third of the herds. Individual cows were assigned their herd nutrition codes by their season of calving. For stepwise discriminant analysis, the group variable was parturient paresis (94 cases, 1,889 controls). As lactation number (most important) and estimated transmitting ability (second most important) increased, incidence of parturient paresis increased. Parturient paresis was reduced with high dietary protein fed during the early stage of the dry period, with low phosphorus and high energy (lead feeding) closer to calving, and with decreased opportunity for exercise. Most cows were overfed calcium, especially in the late stage of the dry period, but calcium intake was not important when phosphorus was low.

Animals↗
PubMed1984

Effect of carbon-4 and carbon-5 volatile fatty acids on growth of mixed rumen bacteria in vitro.

Mixed ruminal bacteria (400 mg cells/liter) were incubated in artificial media containing ammonia, sodium carbonate, macrominerals, vitamins, sulfide, microminerals, acetate, propionate, and butyrate. When mixed carbohydrates (equal parts glucose, maltose, sucrose, cellobiose, and soluble starch) were added at 155 mg/liter per h for 10 h, average bacterial growth rate was slow, and dry weight yield was greater than 23%. Additions of isobutyrate, valerate, isovalerate, and 2 methylbutyrate had little influence on synthesis of bacterial dry weight, deoxyribonucleic acid, ribonucleic acid, or carbohydrate. When a timothy hay inoculum was used, isovalerate and 2 methyl-butyrate increased protein synthesis by 11.2 and 16.4%, but isobutyrate and valerate alone were without effect. All four acids combined increased bacterial protein by 18.7%. Responses with an inoculum of 60% concentrate and mixed hay were smaller and not statistically different from control incubations. Low concentrations of Trypticase (less than 250 mg/liter) improved efficiency of microbial protein synthesis from organic matter, but more was associated with decreased efficiency and utilization of extracellular ammonia.

Ammonia↗
PubMed1984

Protein, fiber, and mineral nutrition of growing dairy goats.

Seven yearling Alpine does were in a series of balance trials to determine apparent utilization of fiber, protein, and minerals. The 34 kg does consumed 2.2% body weight of a hay-concentrate ration that was 18.8% crude protein, 40.9% neutral detergent fiber, 24.7% acid detergent fiber, 1.18% calcium, .67% phosphorus, .39% magnesium, .98% potassium, and .48% sodium. Digestion coefficients were 59.5, 68.5, 42.3, 70.6, and 29.3 for dry matter, crude protein, neutral detergent fiber, hemicellulose, and acid detergent fiber. Retention (g/day) was: 2.6, 1.3, 2.1, 1.8, and 1.1 for calcium, phosphorus, potassium, sodium, and magnesium. Nitrogen intake was related in a positive linear fashion to fecal nitrogen, urinary nitrogen, and absorbed nitrogen. Apparent absorption rates were 2.7, 1.4, 1.3, 5.1, and 3.2 g per doe per day for calcium, phosphorus, magnesium, potassium, and sodium. Mineral retentions as percent of grams apparently absorbed were 96.2, 88.2, 80.9, 37.7, and 56.0.

Animal Nutritional Physiological Phenomena↗
PubMed1983

Association of parturient hypocalcemia with eight periparturient disorders in Holstein cows.

The association between parturient hypocalcemia and 8 periparturient disorders (dystocia, retained fetal placenta, metritis, left displaced abomasum, foot problems, ketosis, mastitis, and coliform mastitis) was evaluated in 33 Holstein dairy herds (2,190 cows) that calved from March 1981 through February 1982. There were highly significant (P less than 0.0001) associations between parturient hypocalcemia and dystocia, retained fetal placenta, ketosis, and mastitis. The odds ratios (multiplicative increases in occurrence) for these associations were 6.5, 3.2, 8.9, and 8.1, respectively. There was a significantly (P less than 0.03) association between parturient paresis and coliform mastitis (odds ratio, 9.0). There was a tendency for association with left displaced abomasum (odds ratio, 3.4; P less than 0.06).

Abomasum↗
PubMed1983

Evaluation of a mathematical model of rumen digestion and an in vitro simulation of rumen proteolysis to estimate the rumen-undegraded nitrogen content of feedstuffs.

Twelve grain mixtures, one lucerne (Medicago sativa) hay and one maize silage which had been used in mixed diets for which dietary nitrogen undegraded in the rumen (UDN) had been estimated with duodenally-cannulated cows, were studied. Total N in the feeds was fractionated into pool A (N soluble in borate-phosphate buffer), pool B (total N--(pool A + pool C)) and pool C (acid-detergent-insoluble N or residual N after 24 h incubation in protease solution). N solubilization in protease solution containing 6.6 units/ml (substrate-saturating enzyme concentration) indicated the presence of subfractions in pool B, with different rates of solubilization. Such subfractions were not detectable from in situ, Dacron bag, estimates of N solubilization. UDN was estimated using a dynamic mathematical model and rate-constants obtained from N solubilization in protease solution or in situ. For three grain mixtures tested using the protease technique the model predicted UDN values of 7, 10 and 12% compared with values of 47, 66 and 59% estimated in vivo. The full range of experimental feeds was tested using the in situ technique and UDN values predicted by the model were used to derive UDN values for twelve mixed diets. The latter values were significantly but not closely correlated with those determined in vivo (r2 0.41, P less than 0.05). An attempt was made to simulate rumen proteolysis in vitro by choosing a protease enzyme concentration (0.066 units/ml) providing a proteolytic activity similar to that of whole rumen fluid. The experimental samples of feed were subjected to simulated rumen proteolysis for 18 or 48 h to resemble the mean retention times in the rumen for grain mixtures and roughages respectively. The residual N at the end of incubation was considered as an estimate of UDN. The UDN values estimated from simulated rumen proteolysis and those determined in vivo for twelve mixed diets were in close agreement (r2 0.61, P less than 0.01). Simulated rumen proteolysis can serve as a simple, rapid and sensitive method to estimate UDN in a variety of feedstuffs.

Animal Feed↗
PubMed1983

Effect of dietary concentration of total nonstructural carbohydrate on energy and nitrogen metabolism and milk production of dairy cows.

Two complete blended diets with a ratio of concentrate: silage dry matter of 60:40 were fed to 12 Holstein cows in the first 12 wk of lactation in an incomplete changeover arrangement of treatments. Diets differed (dry basis) in content of total nonstructural carbohydrate (24.9% versus 32.9%), neutral detergent fiber (37.0% versus 32.1%), and hemicellulose (19.6% versus 15.7%) but were similar in amounts of lignin, crude protein, soluble nitrogen, and acid detergent insoluble nitrogen. The diet with more total nonstructural carbohydrate was associated with greater dry matter intake as a percentage of body weight and greater yields of milk and solids-not-fat. Cellulose digestibility and mean rumen ammonia concentration were lower with this diet. Despite similar protein solubilities, the diet with more total nonstructural carbohydrate contained more rumen degradable nitrogen (80% versus 60%) but similar amounts of rumen degradable dry matter (82% versus 79%). The metabolizable energy of this diet was used more efficiently for the combined functions of maintenance and production, and net energy for lactation was larger (2.2 versus 1.9 Mcal/kg dry matter), as measured calorimetrically.

Ammonia↗
PubMed1983

Effect of carbohydrate limitation on degradation and utilization of casein by mixed rumen bacteria.

Mixed rumen bacteria were incubated in media containing salts, ammonia, vitamins, volatile fatty acids, sulfide, and casein. When initial cell density was 1.0 absorbance unit and mixed carbohydrates (glucose, sucrose, maltose, cellobiose, and soluble starch) were provided at 0, 40, 80, and 160 mg/liter per h, cell growth was limited by carbohydrates, average bacterial growth rate was slow (less than .07/h), and types of bacteria did not appear to change during 7 h. Growth was small if casein was the sole source of energy. Addition of casein to incubations fed carbohydrates caused cell yield to double. Casein hydrolysis was accompanied by marked accumulation of peptides that were metabolized slowly by rumen bacteria. High pressure liquid chromatography indicated that the peptide pool was composed primarily of four fractions. Carbohydrate availability or bacterial growth had little influence on proteolysis or peptide accumulation. Ammonia production was always inversely proportional to rate of carbohydrate feeding. Nitrogen-15 labeling studies indicated that 66% of the cell nitrogen was derived directly from casein at all rates of carbohydrate addition. If average bacterial growth rate was approximately .07/h, little casein entered the ammonia pool even though large amounts of peptide or casein remained undegraded.

Ammonia↗
PubMed1981

Effect of exogenous growth hormone on lactational performance in high yielding dairy cows.

Bovine growth hormone (bGH) was administered to high-yielding Holstein cows fed a complete mixed ration ad libitum. Commencing on day 74 of lactation, 10 cows averaging 34.4 kg milk per day were divided into two groups and received a daily subcutaneous injection of bGH (51.5 IU/day) or a placebo. Injections were continued for an 11-day period and differences in lactational performance, nitrogen balance and estimated energy balance between the two groups were compared for the last 5 days of the preinjection and injection periods. Growth hormone resulted in increases of 9.5% in milk yield, 22.7% in milk fat yield, 14.5% in milk lactose yield and a 17.1% increase in milk energy secretion. Feed intake was slightly reduced (-4.3%, nonsignificant) while milk protein secretion and nitrogen balance were unchanged. Serum growth hormone levels in the bGH group were maintained at the higher concentrations of the normal physiological range during the injection period. By 48 hours following the last injection, declining bGH concentrations approached control values, and milk production decreased to preinjection values. Serum prolactin levels and plasma concentrations of free-fatty acids were slightly increased during the injection period in the bGH group. Growth hormone clearly enhances milk synthesis in the high-yielding dairy cow.

Animals↗
PubMed1981

Oxygen consumption in heifers three months of age related to lactation milk energy.

Calibration techniques were developed for a modified commercial oxygen consumption computer. Oxygen consumption over 5 min by 130 3-mo-old dairy calves was measured 3 h after feeding. Subsequently, Estimated Transmitting Abilities were used to calculate the production potential for lactation milk energy (kcal/305-day lactation) for 88 of the animals. Correlations between lactation milk energy and oxygen consumption or oxygen consumption corrected for weight of calf were calculated by breed. Breed correlations were tested for homogeneity and pooled. The correlation coefficient between oxygen consumption and lactation milk energy was .20 with a 95% confidence interval of -.02 to .40.

Animals↗
PubMed1976

Nutritive value of potato-based silages for dairy bulls.

Diet acceptability, nutrient digestibility, and nitrogen and energy partition were measured in growing Holstein bulls to compare corn silage with three potato-based silages which consisted of (fresh basis): 1) 50% potatoes, 20% hay; 2) 60% potatoes, 20% hay, 20% whole oats; 3) 50% potatoes, 25% hay, 25% whole oats. The 50% potato 50% hay silage dry matter was consumed at 3.0% of body weight per day which was greater than for any of the other three silages. Consequently, daily consumption of each nutrient was generally higher for this silage even though it was lower in content of many nutritional components. Except for ether extract, the digestion coefficients for the 50% potato 50% hay silage were higher than for the other three silages. The addition of whole oats to the potato-based silage tended to depress apparent digestibility of the nutritional components below those for corn silage. Both nitrogen and energy utilization were higher for the 50% potato 50% hay silage than for any of the other three experimental silages. Efficiency of use of absorbed nitrogen was higher for the oat-containing potato-based silages than for corn silage while the oat-containing silages were comparable to corn silage in energy efficiency. The 50% potato 50% hay silage was equal or superior to corn silage in dry matter intake, overall overall digestibility, nitrogen and energy balance for growing Holstein bulls.

Animal Feed↗