Milk production of Holstein heifers fed either alfalfa or corn silage diets at two rates of daily gain.

Seventy-five prepubertal heifers were fed diets based on either alfalfa silage or corn silage plus soybean meal for daily gains of either 725 or 950 g/d in a 2 x 2 factorial. Heifers were fed from 175 to 325 kg of body weight (BW). The alfalfa diet contained more digestible protein and less digestible energy than did the diet containing corn silage plus soybean meal. Actual gains were preexperimental BW gain, 633 g/d; lowest experimental BW gain, 785 g/d; highest experimental BW gain, 994 g/d; lowest postexperimental BW gain, 494 g/d; and highest postexperimental BW gain, 546 g/d. Compensatory postexperimental BW gains of heifers fed a common diet allowed the heifers to calve at 732 d of age. The postcalving BW was 508 kg, and precalving height at withers was 134 cm. A total mixed diet containing 17.1% CP and digestible energy at 3.12 Mcal/kg of dry matter was fed during lactation. Feed intake, milk and milk component production, and milk composition were not affected by either experimental diet or growth rate. As covariates, milk production was related to age at calving and was more strongly related to BW after calving, but no differences were observed among growth diets. Differences in protein and energy concentrations in experimental growth diets did not affect lactation performance. About 75% of total BW gains during the treatment period occurred before puberty, but rate of gain did not affect milk production. This lack of an effect of prepubertal growth rates on the milk production of primiparous heifers is consistent with six other similar studies that were conducted recently.

Components of growth in Holstein heifers fed either alfalfa or corn silage diets to produce two daily gains.

Growth components were compared in an experiment with a 2 x 2 factorial design. Eight replicates of Holstein heifers were fed diets based on either alfalfa or corn silage for daily gain of either 725 or 950 g from 181 to 334 kg of body weight (BW). Mean daily gains from corn diets were greater than gains from alfalfa diets for BW, udder, empty body, fat, fat-free matter, protein, H2O, C, and energy but were less than gains from alfalfa for gut contents and ash. High daily gain produced higher mean values for all of these variables than did lower daily gain. The percentage of protein in fat-free matter was not affected by either main effect. The percentage of fat in empty body gain was increased as daily gain increased. Energy concentration of fat-free matter that was gained was not affected by either diet or daily gain. Energy concentration of empty body gain increased as daily gain increased. The percentage of gut contents in daily BW gain was higher for heifers fed the alfalfa diet than for those fed the corn diet. Energy concentration in daily BW gain was affected by diet and daily gain. Variations of fat and gut contents in daily BW gain must be considered when requirements or expected growth are described.

Glucose and norepinephrine challenges during abomasal infusion of cis or trans octadecenoates in Holstein cows.

This experiment determined the effects of infusion of mixtures of fat containing predominantly cis-C18:1 or trans-C18:1 fatty acids into the abomasum on responses of cows to glucose and norepinephrine challenges administered i.v. Six lactating Holstein cows, each with a rumen cannula, were arranged in two Latin squares with 21-d periods. The common basal diet contained 40% forage and 60% concentrate. Treatments were the uninfused control, 750 g/d of a cis fat mixture (65% high oleic sunflower oil and 35% cocoa butter), and 750 g/d of a trans fat mixture (93% shortening and 7% corn oil) infused into the abomasum via a tube that passed through the rumen cannula. Glucose challenges (0.4 mg/kg of BW, administered i.v.) were conducted on d 18, and norepinephrine challenges (0.7 microgram/kg of BW, administered i.v.) were conducted on d 19 of each experimental period. Despite a lower percentage of fat in milk for trans than for cis treatment, disappearance rates of glucose, secretion of insulin after glucose challenge, and appearance rates of NEFA and triglycerides after norepinephrine challenge were similar between treatments. Thus, these data support the hypothesis that trans-C18:1 fatty acids affect the synthesis of milk fat in the mammary gland of lactating cows.

Influence of prepubertal dietary regimen on mammary growth of Holstein heifers.

One hundred-sixteen Holstein heifers (mean BW, 175 kg) were randomly assigned to diets of alfalfa silage or corn silage and were fed to gain approximately 725 or 950 g/d in order to study the influence of prepubertal diet and rate of gain on mammary growth and milk production. Blood was collected before puberty for hormone determination, and 8 heifers per group were killed at puberty for evaluation of tissue variables. Serum growth hormone was reduced, and IGF-I was increased, in the group of heifers reared at a high rate of gain on the corn silage diet. Accompanying the decline in growth hormone, total mammary parenchymal DNA and RNA was reduced in heifers reared at a high rate of gain on the corn silage diet. Mammary parenchyma in heifers of the latter group contained a greater volume of adipocytes and a lower volume of epithelial cells than did mammary parenchyma in heifers of other groups. Data are consistent with previous investigations that showed a deleterious effect of prepubertal rapid weight gain on mammogenesis when accompanied by excess body fat deposition. However, this effect did not cause a decline in subsequent milk production.

Milk fat depression, the glucogenic theory, and trans-C18:1 fatty acids.

Metabolic and endocrinological characteristics were compared for cows that differed in the extent of milk fat depression. Forty-one multiparous Holstein cows were fed control (40% concentrate and 60% forage) and high concentrate (80% concentrate and 20% forage) diets in a doubale-reversal design. Cows showing one or more percentage units of depression in milk fat were arbitrarily classified as responders (n = 26); those remaining were classified as nonresponders (n = 15). Compared with nonresponders, responders had greater increases in DMI, estimated NEL intake and balance, BW, milk yield, protein and lactose yields in milk, weight percentage of trans-C18:1 fatty acids in milk, and concentrations of triiodothyronine and thyroxine in serum when switched from the control diet to the 80% concentrate diet. Lack of an increase in concentrations of glucose and insulin in serum of cows with the greatest decline in percentage of milk fat casts doubt on the ability of the glucogenic theory to explain milk fat depression completely.

Effects of prepubertal growth rate and diet on lipid metabolism in lactating Holstein cows.

The objectives were to determine the effects of rate of BW gain and type of silage fed before puberty on the partitioning of excess dietary energy between synthesis of milk and BW gain in second or third lactation. Accordingly, 41 Holstein heifers weighing 175 kg were fed diets containing either alfalfa silage or corn silage to gain either 725 or 950 g/d until BW was 325 kg and two estrous cycles were observed. Puberty occurred near 281 kg of BW. During second (n = 36) or third (n = 5) lactation, the cows were fed a control diet (60% forage and 40% concentrate) and a high energy diet (20% forage and 80% concentrate) in a double-reversal experimental design with three 6-wk periods. The rate of BW gain before puberty did not affect the magnitude of changes in DMI, milk yield, milk composition, or concentrations of thyroid hormones, insulin, bST, glucose, or lipids in serum when cows were switched from a control to a high energy diet during second or third lactation. However, compared with cows fed a corn silage diet, cows fed alfalfa silage between 175 and 325 kg of BW had more depressed yields of fat, total solids, and FCM when fed the high energy diet than when fed the control diet during second or third lactation. Increased deposition of fat in adipose and mammary tissues of cows with mean BW gain in excess of 950 g/d or fed a corn silage diet between 175 and 325 kg of BW did not result in more pronounced depression of milk fat percentage when cows were switched from a control to a high energy diet during second or third lactation. Overall, neither rate of BW gain nor type of silage fed between 175 and 325 kg of BW had a major influence on partitioning of excess dietary energy between synthesis of milk and BW gain during second or third lactation.

Prediction of body composition of dairy cows at three physiological stages from deuterium oxide and urea dilution.

To develop equations for predicting body composition, mature Holstein cows (n = 21) were slaughtered at three physiological stages (-7, 63, and 269 d postpartum) after consecutive intravenous dosing with urea and D2O. Blood was sampled at 0 and 12 min after dosing with urea for determination of urea space and from 0 to 72 h after dosing with D2O. Empty body water and total body water were estimated by dilution kinetics for D2O using two- and one-compartment models, respectively. At slaughter, body components were ground, sampled, and freeze-dried for chemical analysis. Prediction of empty body water by urea space was not an improvement over the prediction by body weight alone. Prediction by D2O dilution explained 73 and 87% of the variation in empty and total body water, respectively. Estimated body protein, as determined from empty body water, predicted actual body protein with an error of 4.7 kg. Daily DMI explained 84% of the variation in the DM of the gastrointestinal tract contents (DM fill). Estimations of empty body fat (R2 = .85) and empty body energy (R2 = .89) from D2O dilution were capable of detecting significant differences in body fat (42.9 kg) and body energy (375 Mcal) across physiological stages and might be useful for prediction of body composition changes during the lactation cycle.

National health expenditure projections, 1994-2005.

Using 1993 as a baseline and assuming that current laws and practices continue, the authors project U.S. health expenditures through the year 2005. Annual spending growth has declined since 1990, and, in the scenario reported here, that trend continues in 1994. Growth of health spending increases thereafter, but remains below the average experience of the past decade. Even so, health expenditures grow faster than the gross domestic product (GDP), and by 2005, account for 17.9 percent of the GDP. Unless the system changes, Medicare and Medicaid are projected to pay for an increasing share of total spending during the next decade.

Direct analysis of body composition of dairy cows at three physiological stages.

Holstein cows were killed at three physiological stages, prepartum (-7 d, n = 10), early lactation (63 d, n = 7), and late lactation (269 d, n = 8), for determination of chemical composition and prediction of energy changes during lactation. Cows were weighed, slaughtered, and separated into five or six fractions, including carcass, gastrointestinal tract, mammary gland, uterus, and fetus (if present); the remainder was noncarcass. Live BW and weight of all empty body components except fat were unaffected by physiological stage. Empty body fat was reduced 42.3 kg for the early lactation cows compared with that of prepartum cows. Fat-free matter was similar across physiological stages; however, the water content of fat-free matter was greater for the prepartum and early lactation cows than for late lactation cows. In early lactation cows, the percentages of total protein were less in carcass and greater in gastrointestinal tissue than in prepartum and late lactation cows, but fat distribution was not affected. The energy values of 9.2 and 5.57 Mcal/kg for fat and protein in tissue, respectively, were determined by regression and used to apportion energy associated with fat, .925, and protein, .07, during lactation using data adjusted for ash. A maximum loss of 442 Mcal of tissue energy by approximately 77 DIM was determined by regression of empty body energy on DIM).

Milk fat yield and composition during abomasal infusion of cis or trans octadecenoates in Holstein cows.

The role of trans-C18:1 fatty acids in milk fat depression was examined. Six rumen-cannulated Holstein cows were assigned to two Latin squares with 21-d periods. The common basal diet contained 40% forage and 60% concentrate. Treatments were the uninfused control, 750 g/d of a mixture of cis fat (65% high oleic sunflower oil and 35% cocoa butter), and 750 g/d of a mixture of trans fat (93% shortening and 7% corn oil) infused into the abomasum via a tube that passed through the rumen cannula. Milk yield was similar among treatments. Milk fat percentage and yield were lower, and milk citrate concentration was higher, for the trans than the cis treatment. Changes in the fatty acid composition of milk were similar for the cis and trans treatments compared with the control except for trans-C18:1. The concentration of trans-C18:1 was greater for the cis and trans treatments than for the control and was greater for the trans than for the cis treatment. These data clearly demonstrated that infusion of trans-C18:1 fatty acids into the abomasum depressed milk fat percentage and yield. We speculate that reduced synthesis of fatty acids and reduced activity of acyl transferase in mammary tissue contributed to depressed milk fat percentage for the trans treatment.

Estimating the cost of a Medicare outpatient prescription drug benefit.

People enrolled in Medicare account for more than one-third of all outpatient prescription drug expenditures in the United States. That being the case, a proposed prescription drug benefit under the Medicare program would insure a substantial part of the market and would create the largest expansion of the program in the past 20 years. This article explains how the cost of a drug benefit was estimated as part of the Clinton Administration's health reform initiative.

Why more cost-sharing won't slow Medicare spending.

In considering ways to slow the growth in Medicare expenditures, policymakers have concluded that increasing point-of-service cost-sharing for patients will reduce demand for health services. Under the current system, Medicare beneficiaries faced with increased cost-sharing can reduce their demand for services or purchase additional private insurance. New data from the 1991 Medicare Current Beneficiary Survey show that high-income persons protect themselves from out-of-pocket costs by purchasing private supplemental insurance. Surprisingly, the data also reveal that many low-income persons also purchase private insurance, demonstrating that the elderly--whatever their income level--consider supplementary insurance more of a necessity than a luxury. Thus, it appears that increased beneficiary cost-sharing would have a limited effect on Medicare spending growth.

Health insurance and the elderly.

The effectiveness of proposed changes to the Medicare program depends on consumers' responses to different market incentives, which vary according to the coverage the elderly possess to supplement their Medicare coverage. This Data Watch explores the extent of supplemental insurance among the elderly, based on a new data set from the Medicare Current Beneficiary Survey. Only 11 percent of Medicare beneficiaries have only Medicare as their source of coverage; the rest of the elderly population is covered by either private coverage (employer-sponsored retiree coverage or individually purchased coverage) or Medicaid. An increase in Medicare cost sharing would likely affect one-third of elderly beneficiaries, which calls into question the effectiveness of this approach to Medicare program reform.

Health insurance and the elderly: data from MCBS (Medicare Current Beneficiary Survey).

This article shows the supplemental insurance distribution and Medicare spending per capita by insurance status for elderly persons in 1991. The data are from the Medicare Current Beneficiary Survey (MCBS) and Medicare bill records. Persons with Medicare only are a fairly small share of the elderly (11.4 percent). About three-fourths of the Medicare elderly have some form of private insurance. The share with Medicaid is 11.9 percent, which has increased recently as qualified Medicare beneficiaries (QMBs) started to receive partial Medicaid benefits. In general, Medicare per capita spending levels increase as supplemental insurance comes closer to first dollar coverage. When the data were recalculated to control for differences in reported health status between the insurance groups, essentially the same spending differences were observed.

A computer model to predict empty body weight in cattle from diet and animal characteristics.

A computer model was developed to predict empty BW in cattle as a function of diet (forage NDF, physical form of forage [hay vs silage and pasture], proportion of dietary concentrates) and animal (full BW) characteristics. The model was empty BW = full BW * (1 - GFILL), where GFILL is gut fill expressed as a fraction of full BW. An equation obtained from published data (GFILL = .05354 + .329 * NDF) was used to provide a base prediction of GFILL from the fraction of NDF in the forage. Predicted GFILL was then corrected for full BW, physical form of forage, and fraction of concentrates using multiplicative factors obtained from published data. The model was evaluated with data from 11 published experiments. Several breeds of cattle, a wide range of forage types, and diets with 0 to 93% concentrates were represented in these data. Observed values for empty BW were compared to model-predicted values and to values predicted by systems published by the Agricultural Research Council (ARC) and National Research Council (NRC). Sums of squared deviations of predicted values from observed (n = 64) were 3,074, 37,327, and 25,920 for the model, ARC, and NRC systems, respectively. After fitting predicted empty BW values to observed values, proportion of concentrates and forage NDF accounted for a significant (P less than .01) amount of the residual variation with the ARC and NRC systems, but not for the model. This finding suggests that the model will predict empty BW more accurately than the ARC and NRC systems with diets similar to those used in the evaluation.

Utilization of energy and nitrogen by yearling Holstein cattle fed direct-cut alfalfa or orchardgrass ensiled with formic acid plus formaldehyde.

First-growth orchardgrass and alfalfa were harvested at two stages of maturity, treated with formic acid plus formaldehyde, and ensiled as direct-cut silage during 1978 and 1979. The 1978 silages were fed to eight yearling Holstein heifers (average BW 273 kg), and the 1979 silages were fed to eight yearling Holstein steers (average BW 264 kg) in replicated 4 x 4 Latin square experiments to measure total energy and N balance using the Beltsville open-circuit respiration calorimeters. Silage was offered daily at 70 g of DM/kg.75 BW, a rate that was essentially ad libitum for late-maturity orchardgrass, but restricted for the other three silages within each experiment. Cattle fed alfalfa used ME for growth with greater efficiency (55%) than did cattle fed orchardgrass (40%). Cattle fed orchardgrass achieved the same tissue N retention at a lower total N intake than did cattle fed alfalfa. Differences in tissue N retention were accounted for by differences in N intake insoluble in autoclaved ruminal fluid, but soluble in acid detergent, a fraction termed available N. At equal intake of ME and available N, cattle fed alfalfa gained more tissue energy than those fed orchardgrass and gained tissue protein similarly to cattle fed orchardgrass. Fractions composing digestible OM were different between forage types but similar within forage type between maturities at harvest. More efficient use of ME for growth by animals fed alfalfa compared with orchardgrass may be related to differences in digestible OM composition, load of digestive tract content, and composition of absorbed nutrients.

National health expenditures projections through 2030.

If current laws and practices continue, health expenditures in the United States will reach $1.7 trillion by the year 2000, an amount equal to 18.1 percent of the Nation's gross domestic product (GDP). By the year 2030, as America's baby boomers enter their seventies and eighties, health spending will top $16 trillion, or 32 percent of GDP. The projections presented here incorporate the assumptions and conclusions of the Medicare trustees in their 1992 report to Congress on the status of Medicare, and the 1992 President's budget estimates of Medicaid outlays.