F.G. Owen’s research while affiliated with University of Nebraska–Lincoln and other places

Feed costs were determined using linear programming techniques to produce least cost dairy diets. Effects of alfalfa hay and corn silage price and maturity of alfalfa hay on daily diet costs were determined. The influence of soybean meal price on the effects of alfalfa hay and corn silage price was also included. Regression equations were generated defining the responses in diet costs to changes in prices of these feeds and to maturity of alfalfa hay. Increasing alfalfa hay price from $40 to$120/909 kg increased feed cost per cow daily less ($.34) with low priced soybean meal (120/909 kg) than with high priced soybean meal ($.77). As corn silage price increased from $12.60 to$32.20/909 kg, daily feed cost per cow increased between $.81 and .96 daily with various price combinations for alfalfa hay and soybean meal. The response in diet cost to increasing the price of corn silage was affected little by alfalfa hay or soybean meal price. Increasing alfalfa hay maturity from immature to mature increased the cost of all diets. However, the effect of maturity on diet costs was greater with higher priced corn silage and with higher priced soybean meal. Advancing maturity increased diet cost more with$40 hay than with $120 hay. These results emphasize the importance of early harvest of alfalfa hay as one of the major factors in reducing the feed cost for producing milk.

Twelve midlactation Holstein cows were assigned to a switchback design with 4-wk periods to compare a corn gluten meal and blood meal mixture with soybean meal as supplemental protein sources. All experimental diets contained 60% ammoniated corn silage, on a dry basis, and a corn and oats (2:1) basal concentrate mixture. Diets were: urea control (12.5% CP); soybean meal (16.1% CP); low protein (14.3% CP) corn gluten and blood meal mixture; and high protein (16.8% CP) corn gluten and blood meal mixture. Cows fed the control diet consumed less DM, and produced less milk containing a lower percentage of protein than cows fed other diets. Protein efficiency and milk fat percentage were higher for cows fed the control diet than for cows fed the natural protein diets. Fat-corrected milk and fat yields did not differ among diets. The high protein diets (16.1 and 16.8% CP) decreased protein efficiency and increased SNF percentage. Milk yield per unit of DM intake was higher when cows fed the lower degradable protein source (corn gluten-blood meal) than when they were fed soybean meal. The low degradable protein mixture produced a similar lactation response to soybean meal at both the high and low concentrations of total dietary protein. This study indicates that the dietary protein and undegradable protein concentration needed by midlactation Holstein fed complete mixed diets may be lower than generally recommended.

Fifty-four multiparous Holstein cows were used to compare the influence of intake on digestibility of three diets. All diets contained a 50:50 ratio (dry basis) of ammoniated corn silage and concentrate. The control concentrates consisted of corn, oats, and soybean meal. The two test concentrates contained either 43.8% soyhulls or 71.6% corn distillers dried grains with solubles. Each diet was fed at three intakes. Dry cows were fed one times maintenance intake, cows producing 10 to 20 kg milk daily were fed at twice maintenance, and cows producing 27 to 49 kg daily were fed ad libitum (four times maintenance). Digestibilities of DM for the control, distillers grains, and soyhull diets, respectively, were: for dry cows, 84.1, 66.6, and 78.8%; for medium producers, 76.6, 53.8, and 74.2% and for high producers, 60.5, 44.3, and 62.8%. At ad libitum intake, the DM, NDF, ADF, and CP digestibilities were lower for control than for the soyhulls diet. Discounts per unit of maintenance of 9.3, 11.2, and 6.8% were obtained for the control, distillers grains, and soyhull diets. These results confirm the generally accepted concept of energy discounts for grain-soybean meal diets, but discounts were higher than reported previously. Compared with the control diet soyhulls appears to lower, and distillers grains increase, the discount.

Twelve multiparous Holstein cows were used in a balanced, two-period, changeover design to evaluate soyhulls as a replacement for corn grain in lactation diets. Soyhulls constituted 0 (corn), 50 (corn-soyhull), and 95% (soyhulls) of the concentrate mixture, which was prepared as a 4.8-mm pellet. These concentrate mixtures were mixed with alfalfa silage (50:50 DM) and fed ad libitum as complete diets. Mean DM intakes averaged 23.7 kg/d and were similar for corn, corn-soyhulls, and soyhull diets. Corresponding daily milk yields averaged 29.8, 28.9, and 27.3 kg and milk fat averaged 3.13, 3.33, and 3.49%, resulting in similar 3.5% FCM yields and feed efficiency. Dry matter digestibility was higher for the corn diet (70%) and the corn-soyhull diet (69%) compared with the soyhull diet (61%). Digestibilities (%) of NDF were 55, 63, and 58; ADF were 56, 62, and 55; and CP were 66, 64, and 59 for corn, corn-soyhull, and soyhull diets, respectively. The gastrointestinal passage rate of alfalfa and of soyhulls was similar among diets. The energy value of soyhulls appears to be equal to corn in pelleted concentrates. The fat-depressing effect of pelleting a high starch (corn) concentrate was minimized by including soyhulls.

Fifty-four lactating Holstein cows were assigned by parity and calving date to a 2 X 3 factorial arrangement of a randomized block design to determine effects of beta-carotene supplementation and ration fiber content on reproduction. Because ration fiber treatments did not differ in their effects on reproductive performance, data for beta-carotene analyses were pooled over the three rations. From 3 to 98 d postpartum, cows were individually fed either 0 or 300 mg supplemental beta-carotene daily by adding it on top of their complete mixed ration. By wk 3 postpartum, concentrations of beta-carotene in blood serum were higher in cows fed supplemental beta-carotene and remained higher throughout the experimental period. Feeding supplemental beta-carotene had no effect on the interval from the time of parturition to uterine involution, ovulation, first observed estrus, or conception. Feeding beta-carotene did not influence incidence of cystic follicles based on palpation, ovarian cyclicity based on blood progesterone patterns, peak progesterone concentrations, or first service conception rate. Cows fed supplemental beta-carotene required fewer treatments for clinical mastitis. Reproductive performance in lactating Holstein cows was not improved by feeding supplemental beta-carotene.

Two trials involving 57 Holstein cows were conducted to determine the effect of feeding 300 mg supplemental beta-carotene from 30 days before expected parturition to 98 days postpartum on periparturient health and subsequent reproductive performance. Feeding supplemental beta-carotene reduced (P < 0.05) the dystocia score in trial 1 only. Supplementation had no effect (P > 0.05) on the incidence of placental retention and ovarian cysts, rate of uterine involution, fertility, milk production or somatic cell counts. Thus, benefits in health, reproduction or milk production were not generally observed from feeding supplemental beta-carotene to Holstein cows fed a diet commonly used in the United States.

Various physiological and environmental factors were examined for possible association with retention of the fetal membranes in a herd experiencing a high incidence of this problem. Data were collected on 116 multiparous and primiparous cows during the first lactation of the trial and 57 multiparous cows during the second lactation of the trial. No mineral or heavy metal deficiencies or toxicities were detected in the herd and injections of selenium and/or vitamins A, D and E during the prepartum period were not beneficial. Also, no common disease entity could be found in this herd. Placental retention rates observed were 28% and 42% in the first and second lactations, respectively, of this study. The incidence of retained placenta was higher in cows giving birth to twins or male calves, and following abortions, stillbirths or placental retention at the previous parturition. Seasonal effects varied, with a higher retention rate in the warm season in the first lactation and in the cold season in the second lactation. Factors examined that did not show a statistically significant relationship to the placental retention rate included: blood serum vitamin A and β-carotene concentrations; age or lactation number; calf birth weight; presence of serum antibodies to leucosis or chlamydia; incidence of milk fever or ketosis; and services per conception, days open and gestation length of the pregnancy prior to retention. Cows with retained placenta subsequently had longer postpartum intervals to first ovulation and more uterine infections, foot problems and mastitis than cows without retained placenta.

Scientists at 16 experiment stations have been involved in cooperative research to study methods of increasing efficiency and for improving management of dairy replacements. This research is part of the Regional Research Project NC-119 "Improving Large Dairy Herd Management Practices." Research objectives have concerned means of increasing efficiency of producing replacements for large dairy herds. Through cooperative research, important answers were found to questions involving nutrition, housing, and management for replacement animals. Between 1977 and 1982, over 50 articles have been published in journals and trade magazines on replacement animal rearing from research of the NC-119 project. These results should have wide impact and use on livestock management.

Milk samples were collected from 82 Holstein cows during the 1st yr of a 2-yr study and from 44 of these again in the 2nd yr to determine relationships of iodine and beta-carotene concentrations in milk to age, season, placental retention, uterine infections, clinical mastitis, services per conception, and milk yield. Composite milk samples were collected twice weekly at the morning milking. Milk samples from each cow were pooled prior to analyses for the following three times: 1 to 7 wk and 8 to 14 wk postpartum in yr 1 and 1 to 6 wk postpartum in yr 2. Beta-carotene concentrations of milk were inversely related to milk yield and positively related to milk fat percentage. Concentrations tended to be higher for cows experiencing health problems, probably because of lower milk yields and the concommitent higher milk fat content. The relatively low milk iodine concentrations were not generally related to cow age, season of calving, milk yield, milk fat percentage, or to health and performance measures.

One hundred and twenty Holstein cows were assigned to a randomized complete block design to determine effects of selenium, vitamins, and ration fiber on incidence of placental retention and other health and reproductive problems. The selenium treatment (50 mg selenium, 680 IU vitamin E) was administered as a single injection approximately 3 to 4 wk prepartum. The vitamin treatment (3 million IU vitamin A, 450,000 IU vitamin D3, 300 IU vitamin E) consisted of two injections, one administered at 3 to 4 wk prepartum and another at 2 to 3 wk postpartum. Fiber treatments were: control, 15.7% crude fiber; beet pulp, 19.3% crude fiber; and soyhull, 19.0% crude fiber. Feeding of experimental rations was begun 1 day postpartum, and the ration effect on placental retention was examined only at subsequent parturition. The overall placental retention rate of 28% was not affected by either selenium, vitamin, or combined treatments. Ration treatments did not affect the placental retention rate of 42% at subsequent parturition. Cows receiving the soyhull ration required fewer services per conception. Incidence of foot problems tended to be higher in the cows that received the combined selenium and vitamin A, D, E treatments. Supplemental selenium, vitamins A, D, and E, and ration fiber treatments did not reduce incidence of placental retention or improve most other health and reproductive measures.