Effect of fiber content and particle size of alfalfa silage on performance and chewing behavior.

A low NDF drought-stressed 1988 alfalfa silage (32.6% NDF) and a higher fiber 1988 alfalfa silage (46.4% NDF) were fed to lactating cows to evaluate effects on feed intake, fat test, and chewing behavior. Two groups of Holstein cows, 16 primiparous housed in tie stalls and 16 multiparous in free stalls, were assigned to diets based on parity and milk yield. The low NDF silage was fed for 6 wk in a TMR with 21.5% NDF and was compared with a TMR with 31.9% NDF. During an additional 4-wk period, one-half of each dietary group was fed a ration in which one-half of each silage was rechopped to reduce particle size. All rations contained a 1:1 ratio of forages to concentrates (DM basis) and were fed for ad libitum intake. Diets with 21.5% NDF and reduced particle size had no influence on milk fat percentage, 4% FCM yield, or plasma glucose. Cows fed these diets had reduced chewing time, due largely to decreased rumination time. Rumination and total chewing times per unit DMI and FCM also were lowest on these diets. Intake of DM on a BW basis was lowest for cows fed the low NDF rechopped silage diet. Cows fed in tie stalls had more eating bouts than those in free stalls, but total eating times were similar. Sufficient amounts of effective fiber appeared to be present in low NDF and rechopped silage diets to prevent the systemic events leading to milk fat depression but not to prevent a reduction in chewing time.

Effect of particle size of forage and rumen cannulation upon chewing activity and laterality in dairy cows.

Three ruminally cannulated Holstein dairy cows housed in free stalls (with .7% slope) were fed three total mixed rations, differing in silage particle size, in a 3 x 3 Latin square design. Observations on cow behavior were made every 5 min during 24 h for each of three periods. Additional observations of six cows (three intact, three cannulated) housed under identical conditions yielded information concerning recumbent rumination activity and laterality. Results indicated that decreasing particle size of forage reduced time spent ruminating, whether standing or recumbent, and had no effect upon rumination rate or number of rumination bouts per 24-h period. Eating time was unaffected by treatment. Effect of forage particle size upon baseline rumination activity appeared to be most pronounced from 0800 to 2000 h, although maximum rumination activity occurred during nighttime hours. Ruminally cannulated cows demonstrated increased right-side laterality (70%) compared with intact cows (47%), but the cows tend to ruminate while lying on their left side. The percentage of time spent ruminating while recumbent on the left side was similar (55%) for intact and cannulated cows.

Maternal transfer and retention of supplemental selenium in neonatal calves.

Selenium concentrations in blood serum of heifer calves from dams fed 0, 1, or 5 mg supplemental selenium daily during the dry period were compared. Dry cows were fed corn silage top dressed with a soybean meal mineral mix containing the desired amount of selenium. At birth, calves were assigned to one of six treatments in a 3 x 2 factorial arrangement. Calf treatments were 0, 1 (at birth), or 2 (at birth and 14 days of age) injections of selenium/vitamin E with feeding of starter commencing at 14 or 28 days of age. Dosage per injection was .078 mg selenium and 5.4 IU vitamin E per kilogram body weight. Selenium concentrations of blood serum of cows at parturition were 14, 32, and 58 ppb for cows fed 0, 1, and 5 mg selenium per day. Amount of selenium fed to cows affected selenium concentrations in blood serum of their calves with those from cows fed 5 mg selenium having the greatest concentrations. Calves from cows fed no supplemental selenium showed increased selenium in serum at day 28 and 42 when given one or two injections of selenium. Two injections, however, were necessary to elicit a response in calves from cows fed 1 mg per day. Selenium in blood serum of calves from cows fed 5 mg per day was not elevated when calves were given one or two injections of selenium. Prepartum selenium supplementation of the dam elevated selenium of blood serum in the calf at birth.(ABSTRACT TRUNCATED AT 250 WORDS)

Selenium/vitamin E: role in disease prevention and weight gain of neonatal calves.

A 3 X 2 factorial arrangement of treatments comparing 0, 1, or 2 injections of a selenium/vitamin E preparation and feeding of starter commencing at 14 or 28 days of age was used to examine effects of supplemental selenium/vitamin E on health and growth of neonatal calves. Dosage per injection was .078 mg selenium and 5.4 international units of vitamin E per kg body weight. Neither a single injection at birth nor two injections (birth and day 14) reduced incidence of respiratory diseases or improved weight gains in unstressed calves. Calves first offered starter at 14 days as compared with 28 days gained more weight in the 56 days. A single injection of selenium/vitamin E at birth increased selenium of blood serum at day 14 by 87%, and a second injection increased selenium of blood serum at day 28 an additional 10%. Selenium of blood serum of calves not given an injection decreased linearly from birth to day 56. Calves first fed starter at day 14 had lower concentrations of selenium of blood serum from day 28 to 42 than calves first offered starter at day 28. Glutathione peroxidase activity of erythrocytes was higher in calves receiving one or two injections of selenium/vitamin E than in control calves; however, a lag of 4 to 5 wk occurred between injections and elevation of glutathione peroxidase activity.

Ammonia and urea in corn silage-based complete mixed diets for dairy cows.

Source of supplemental N was evaluated in three corn silage-based complete mixed diets (CMD) fed to lactating dairy cows. Diets were formulated to be isonitrogenous and contained 60% corn silage and 40% concentrate on a dry matter basis. Diets were: CMD-A, ammoniated corn silage (ammonia provided 16% of total N) plus concentrate; CMD-U, untreated corn silage and concentrate (16% of total N from urea) and CMD-S, untreated corn silage plus concentrate with soybean meal. Ammoniation at 1.0% of dry weight increased crude protein content of silage from 8.5 to 12.7%. Daily means for cows fed CMD-A, CMD-U and CMD-S were: 24.2, 24.3 and 24.5 kg of fat-corrected milk; 3.17, 3.10 and 3.15% milk protein; 3.41, 3.67 and 3.63% milk fat and 3.02, 2.99 and 3.02 kg intake of total dry matter/100 kg body weight. Differences were not significant except for reduced milk fat percentage for cows fed the ammoniated corn silage diet. Both anhydrous ammonia and urea at 16% of total dietary N were found to be practical and economical substitutes for part of the supplemental soy protein. When compared to CMD with all soybean protein, greater savings in feed costs resulted from inclusion of ammoniated corn silage than with inclusion of urea.

Effect of th brown midrib-three gene on corn grain utilization by growing rats.

A study was conducted to determine the effect of the brown midrib-three (bm3) gene for low lignin in corn plants on grain utilization by growing rats. No differences in total body weight gain were observed between rats fed bm3, normal and iso-N bm3 (isonitrogenous to normal) grain diets with or without supplemental dietary protein. Body weight gains for rats fed bm3, normal and iso-N bm3 grain diets were 39.6, 35.2 and 31.6 g, respectively, when no supplemental protein was fed, and 134.6, 142.1 and 132.2 g when supplemental protein as soy protein was fed to increase crude protein to 11 to 12%. No differences in feed conversion were observed between rats fed bm3, normal and iso-N bm3 grain diets at either level of dietary protein. Feed to gain ratios were 8.7, 9.4 and 10.7 when no supplemental protein was fed and 3.2, 3.2 and 3.4 when supplemental protein was fed. According to this study, this bm3 gene has no effect on grain utilization by the growing rat.

Variables associated with peripartum traits in dairy cows. VII. Hormones, calf traits and subsequent milk yield.

Independent effects of certain partum and peripartum traits on subsequent milk yields (Y) during days 1 to 27 (Y27), 28 to 60 (Y60) and 1 to 200 (Y200) of lactation were estimated from data on 167 Holstein cows and first-calf heifers. The variables were health status, calf sex and covariates (linear, quadratic and cubic) of calf birth weight (CBW), cow age (CA), month of calving code (season) and the peripartum blood plasma concentrations (means of three samples taken from 48 hr prepartum to within 2 hr postpartum) of prolactin (PRL), progesterone (P4), estrone (E1), estradiol-17 beta (E beta) and estradiol-17 alpha (E alpha). Except for Y200 values, the measures of milk yield were positively correlated (P < .01) with each other and with CA, CBW, plasma PRL and plasma E beta. Plasma PRL, E beta and E1 were positively correlated with each other and with CA (PRL and E beta) and CBW (E1 and E beta). Covariates prominently and independently related to increases in Y were CA, CBW and plasma PRL (P < .01). Predicted Y27, Y60 and Y200, calculated with equations of the cubic model, increased by 12.4, 6.5 and 3.7%, respectively, between CBW of 37 and 50 kg, and by 16.6, 15.9 and 14.8% between plasma PRL concentrations of 50 and 195 ng/ml. Season of calving, calf sex and health status were associated with changes in Y27 but not Y60 or Y200. Within the health status group, only infectious disorders (metritis or mastitis) decreased (P < .025) milk yield adjusted for CA and cow weight (adjusted Y60 and Y200). Among all other cows, including those with dystocia alone, adjusted yields were increased by heavier calves (P < .07, Y60), high plasma PRL (P < .025, Y60) and below average plasma E1 (P < .025, Y200). It may be practical to increase milk yield by providing supplemental light prepartum to increase plasma PRL and by selecting sires to maintain CBW above average.

Variables associated with peripartum traits in dairy cows. I. Effect of dietary forages and disorders on voluntary intake of feed, body weight and milk yield.

Daily voluntary intakes of feed by each of 89 Holstein cows were compared between day 220 of gestation and day 30 postpartum over a 21-month period. Diets designed to meet NRC requirements and which contained either chopped hay (29 cows), hay crop silage (HCS; 30 cows) or corn silage (CS; 30 cows) were compared prepartum (27 to 0 days), peripartum (1 day before to 3 days after calving) and postpartum (days 4 to 30 postpartum). Mixed rations, fed during lactation, were 60% forage and 40% concentrate dry matter (DM). Cow management was similar to commercial operations. The experimental hypothesis was that pre-disposition for partum and postpartum disorders (abnormal) could be related either to voluntary intake of different diets or to physical traits. Intakes (DM or estimated net energy) across diets decreased 30% between days 7 and 1 prepartum and averaged 18% and 20% lower peripartum and postpartum, respectively, in abnormal cows than in control cows. Seasonal effects on intakes were significant. In general, changes in body weight and condition and differences in udder edema and milk yield reflected intakes. The results support the original hypothesis.

Variables associated with peripartum traits in dairy cows. II. Interrelationships among disorders and their effects on intake of feed and on reproductive efficiency.

Daily individual voluntary intakes of dry matter (DM % of body weight) and estimated net energy (ENE, Mcal/100 kg) by 89 Holstein cows were compared between day 220 of gestation and day 30 postpartum over a 21-month period. The purpose was to compare effects of diet and health status (control vs. abnormal) on intakes of DM and ENE. The cows were fed either chopped hay, hay crop silage (HCS) or corn silage (CS). Compared to controls, voluntary intakes of DM and ENE were decreased (most to least) in cows with fat cow syndrome (FCS), parturient paresis (PP), mastitis (MST), retained fetal membranes-metritis (RFM-M), and displaced abomasum (DA) prepartum and FCS, DA, PP, RFM-M and MST peripartum. Cows fed hay had a lower incidence of RFM-M (28%) than cows fed HCS (57%) and CS (47%) as well as superior reproductive efficiency subsequently (89% conceived vs. 72% and 78%, respectively).

Variables associated with peripartum traits in dairy cows. III. Effect of diets and disorders on certain blood traits.

BLood samples were collected from 89 Holstein cows on days 220 and 250 of gestation, within 24 hr prepartum and postpartum and on day 30 postpartum. Balanced diets which contained either chopped hay (29 cows), hay crop silage (HCS; 30 cows) or corn silage (CS; 30 cows) were fed from day 220 of gestation to day 30 postpartum. The purpose was to determine if variations in certain blood traits were indicative of peripartum and postpartum disorders. The blood traits evaluated were concentrations of plasma total protein, whole blood hemoglobin, packed cell volume, and white blood cells, and serum glutamic oxalacetic transaminase (SGOT), glucose, urea nitrogen, calcium, inorganic phosphorus, magnesium, potassium and sodium. No blood trait was useful to predict a disorder prior to its visual signs with one possible exception. Serum glucose and calcium were lower and SGOT and magnesium were higher peripartum which was prior to death of three cows from fat cow syndrome.