Three reproductive management systems designed to use prostaglandin F2α (PGF) to save labor needed for estrous detection and artificial insemination (AI) were compared to conventional dairy herd reproductive management to evaluate their potential to maintain herd reproductive performance. The four experimental groups were: (1) CONTROL = daily estrous detection for AI with no PGF intervention, (2) Appointment (APPT) AI = double PGF injection at a 12-day interval followed by single appointment AI at 72 hrs for first AI, with repeat AI based on estrous detection, (3) 7-DAY = weekly (Monday) PGF injection for all cows ready for first or repeat AI with AI based on estrous detection which occurred only four days (Wednesday through Saturday) of each week, and (4) 21-DAY = repeating 21-day blocks of 13 days of AI based on estrous detection with PGF given on day 8 to cows yet to be inseminated and 8 days with no estrous detection or AI. All cows in all groups became eligible for breeding after a voluntary waiting period (VWP) of 54 days.

We studied the effect of increased energy density of diets during early lactation on lactational performance of cows injected with bST. Total mixed rations contained 50% forage (DM) and 2.5% choice white grease during the first 14 wk of lactation. Thirty cows were fed diets with grease as the only supplemental fat, and 15 cows were fed grease plus 1.8% calcium salts of long-chain fatty acids. One-half of the cows fed grease and all cows fed grease plus calcium salts of long-chain fatty acids received 640 mg/28 d of sustained-release bST from 6 to 44 wk postpartum. Calcium salts of long-chain fatty acids did not increase milk yield, 3.5% FCM, or DMI during the first 14 wk postpartum or during 15 to 44 wk postpartum. Administration of bST increased milk fat concentration .4% units during the first 14 wk postpartum. Cows receiving bST had higher DMI and produced 18.5% more 3.5% FCM from 15 to 44 wk postpartum than did controls. Calcium salts of long-chain fatty acids or bST injections did not influence body condition score or BW. These data suggest that cows yielding 30 to 35 kg of milk/d during the first 14 wk of lactation may not respond to added fat over 2.5%.

The decision whether to grow an alternative crop is often complex and of much contemporary relevance as producers seek to diversify and buffer their farming operations against increasing costs and volatile commodity prices. In recent years, white lupin (Lupinus albus L.) has been proposed as an alternative crop for on-farm production of dairy protein supplement in the North Central USA. This case considers a situation faced by a Central Minnesota dairy producer in 1991 as he decided whether to attempt to grow lupin as a protein supplement on his farm. The producer had previously made three attempts to produce lupin in 1988–1990. These attempts had been unsuccessful because of a combination of drought and weed problems. The case was developed as a format for stimulating in-depth consideration and discussion of factors involved in alternative crop adoption. The case hinges on two questions; whether lupin can be successfully grown on the farm and whether lupin can supply adequate protein for the farm's high-producing dairy herd? The case also illustrates how human factors can be important in many production decisions through consideration of the producer's determination and perseverence in the face of adversity. In deliberating the case decision, students need to integrate both agronomic and ruminant nutrition factors. The case has been class-tested twice with students rating it “good” to “very good” for its effectiveness at familiarizing them with issues and factors associated with alternative crop adoption.

Effects of temperature, aeration, and DM on fermentation of alfalfa were evaluated. Third cutting alfalfa at 46 and 62% DM was ensiled for 21 d in laboratory silos maintained at 38 and 65°C, and subjected to aerated and anaerobic conditions. Samples were withdrawn at d 1, 2, 7, and 21 and analyzed for DM, pH, VFA, lactic acid, NDF, ADF, ADIN, lignin, ash, total N, NPN, and NH3N. Dry matter loss, calculated from ash content, ranged from .2% DM for d 1 to 2.7% DM on d 21. Low DM silages contained more lactate and acetate than high DM silages. High ensiling temperatures reduced production of organic acids. Slight molding took place in most of the silages at low temperature. Analysis of the fiber fractions revealed an increase in NDF and ADF, particularly in high temperature silages. The percentage increase was greater for NDF than ADF in high DM, high temperature silages. Concentrations of NPN were greater in low DM silages than high DM silages, but high DM silages contained the most ADIN. Lignin and ADIN increased in high temperature silages, but the latter was not greater than .4% of DM after 21 d in the silo.

Sodium (Na) deficiency was observed as a cause of decreased production and associated with polyuria/polydipsia (PU/PD) in a herd of dairy cows. Subsequent investigations revealed other herds experiencing milk loss due to Na deficiency, however PU/PD was not observed in all cases. To further study Na deficiency and diagnostic tests to confirm a diagnosis of NaCl deficiency, sixteen mid-to-late lactation dairy cows were divided into 2 groups for a 30 day Na depletion study. The control group (C) received 0.75% NaCl in their concentrate while the deficient group (E) was fed a ration without supplemental Na. There was a significant difference in production decline (9.5% vs. 29.3%) between C (25.1 to 22.7 kg) and E (18.8 to 13.3 kg). A significant difference in urine Na was observed between C vs. E (29.7 to 21.4 vs. 43.4 to 1.8 mEq/L) and in faecal excretion of Na (FENa) of C vs. E (0.357 to 0.205 vs. 0.329 to 0.016%). A significant decline in serum K was demonstrated between C vs. E (4.43 to 4.61 to 1.8 mEq/l, P<0.01), while FEK increased (39.27 to 36.68 vs. 39.47 to 50.78%). There were no significant differences observed in serum Na or other serum parameters between groups. The diagnostic values of FENa and urine Na determinations was very high. A significant difference between control and depleted animals in both determinations was observed in both experimental and field conditions. Therefore the simple determination of urinary Na concentration in a herd of lactating dairy cows can be used to diagnose Na deficiency. Sampling of 5 high producing cows could be recommended since they would be at greatest risk of deficiency in borderline salt supplementation situations.

Sixteen primiparous Holstein cows with retained fetal membranes (RFM) were studied for postpartum prostaglandin release, uterine infection and resumption of estrous cyclicity after manual removal of RFM (eight cows) versus leaving the RFM untreated (eight cows). The RFM were results of induced parturition on Day 274 of gestation. Seventeen non-RFM primiparous cows were controls. The 15-keto-13, 14-dihydro-metabolite of prostaglandin F(2alpha) (PGFM) was measured in daily blood samples. Aerobic and anaerobic bacteria were cultured from weekly uterine swabs from Week 3 until results were negative. Resumption of estrous cyclicity was determined by milk progesterone three times weekly. Manual removal caused an immediate and large but short-lived increase in PGFM, probably due to the physical damage of uterine tissue. No sustained difference in postpartum PGFM release between cows with RFM manually removed and cows with RFM left untreated was detected. Non-RFM controls had lowest PGFM concentrations. Uterine infections were more frequent and more severe after manual removal of RFM. Untreated RFM-cows and controls were similarly affected. Most infections involved Actinomyces (formerly Corynebacterium ) pyogenes and/or Fusobacterium necrophorum . Actinomyces pyogenes was isolated in the third week postpartum in 5 8 cows with RFM manually removed versus 2 8 cows with RFM left intact and in 2 17 controls. Manual removal prolonged the interval from calving to first functional corpus luteum by 20 d. This study, using RFM resulting from induced parturition, shows that manual removal of RFM can delay the postpartum return to normal reproductive status without altering PGFM profiles.

Holstein cows in early lactation were used to compare three combinations of extruded whole soybeans and corn gluten meal to soybean meal. Treatments were (as a percentage of supplemental crude protein) 100% soybean meal; 75% whole soybeans extruded at 149°C, 25% corn gluten meal; 50% extruded soybeans, 50% corn gluten meal; and 25% extruded soybeans, 75% corn gluten meal. Diets were formulated to be 37.5% corn silage, 12.5% alfalfa cubes, and 50% concentrate (dry matter). Dietary crude protein was 15.7% of dry matter, and supplemental protein sources supplied 27% of total dietary protein. Diets were fed as total mixed rations and data were collected from 4 to 116 d postpartum.

An account is given of the effects of somatotropin on milk yield and composition, feed intake, health and reproduction, and of the effect of stage of lactation on the response to somatotropin. Economic aspects are considered.

Sixty-eight Holstein cows were fed diets consisting of 60% concentrate and 40% forage, dry basis. Diets were supplemented with DL-methionine or methionine hydroxy analog at either 0, .1, .2, or .3% of the concentrate. Dietary protein averaged 14% of total dry matter on all diets except for a positive control diet, which was 19% crude protein. Data were collected beginning 4 d postpartum and continued through 116 d postpartum. Milk yield was not influenced by either DL-methionine or methionine hydroxy analog. Supplementation with DL-methionine resulted in a quadratic response in milk fat percentage (3.34, 3.58, 3.72, 3.42) at 0, .1, .2, and .3% of the concentrate, respectively. Milk fat percentage increased linearly (3.34, 3.64, 3.60, 3.73) with supplementation of methionine hydroxy analog at 0, .1, .2, and .3%, respectively.

Three lactating Holstein cows with rumen cannulae were used in a 3×3 Latin square arrangement of treatments to study effects of methionine source on ciliated protozoa numbers and volatile fatty acid concentrations in the rumen. Cows were fed total mixed diets twice daily of 60% grain mix, 21% corn silage, and 19% alfalfa hay (dry basis). Methionine hydroxy analog, DL-methione, and sodium sulfate were added on an equal sulfur basis. Experimental periods were 14 d with four rumen samples taken daily on d 13 and 14. Total ciliated protozoa were higher when cows were fed DL-methionine than when fed methionine hydroxy analog or sodium sulfate. Ruminal concentrations of butyric acid and isobutyric acid were higher for the DL-methionine treatment than for analog or sodium sulfate treatments. Isovaleric acid concentrations were also higher in fluid from cows fed methionine compared with cows fed the analog.

In two trials, 47 and 54 Holstein cows were fed diets containing ensiled forages, ensiled and dry forages, or diets of different moisture contents. In trial 1, diets were fed during a preliminary dry period, early lactation, late lactation, a second dry period, and a second early lactation. In trial 2, four diets identical except for moisture content (78, 64, 52, and 40% dry matter) were fed for the first 200 days of lactation. Substitution of dry hay for alfalfa silage increased dry matter intake during the first early lactation, whereas partial substitution of corn silage with straw did not affect intake during dry periods. Dry matter intake increased linearly as dry matter content of diet increased in trial 2. Neither milk production nor body weight were affected by treatment in either trial. Percentage total solids increased linearly as dry matter content of diet decreased in trial 2. Volatile fatty acids differed slightly, but no trends were consistent. No differences of daily chewing time were observed. From these trials, diets of less than 60 to 65% dry matter may reduce intake by lactating dairy cows.