Differential response to stocking rates and feeding by two genotypes of Holstein-Friesian cows in a pasture-based automatic milking system.

The throughput of automatic milking systems (AMS) is likely affected by differential traffic behavior and subsequent effects on the milking frequency and milk production of cows. This study investigated the effect of increasing stocking rate and partial mixed ration (PMR) on the milk production, dry matter intake (DMI), feed conversion efficiency (FCE) and use of AMS by two genotypes of Holstein-Friesian cows in mid-lactation. The study lasted 8 weeks and consisted in a factorial arrangement of two genotypes of dairy cattle, United States Holstein (USH) or New Zealand Friesian (NZF), and two pasture-based feeding treatments, a low stocking rate system (2 cows/ha) fed temperate pasture and concentrate, or a high stocking rate system (HSR; 3 cows/ha) fed same pasture and concentrate plus PMR.

Constraints for nutritional grouping in Wisconsin and Michigan dairy farms.

A survey was conducted in Wisconsin (WI) and Michigan (MI) to quantify the proportion of farms that use a single diet for all lactating cows and to better understand the reasons for current grouping strategies and the limitations to grouping for better nutritional management. A questionnaire was mailed to all WI dairy farmers with ≥200 lactating cows (971 farms) and to a random sample of grade-A MI dairy farmers (800 farms) of varying herd sizes. The survey return rate was 20% in WI (196 farms) and 26% in MI (211 farms; 59 of them had ≥200 lactating cows).

Response profiles of enteric methane emissions and lactational performance during habituation to dietary coconut oil in dairy cows.

Dietary coconut oil (CNO) can reduce dry matter intake (DMI), enteric methane (eCH(4)) emissions, and milk fat yield of lactating cows. The goals of this research were to examine responses to different CNO concentrations during the habituation period (34-d) and to evaluate temporal patterns of DMI, eCH(4), and milk fat yield. Treatment diets contained (dry basis): 0.

Preference and drinking behavior of lactating dairy cows offered water with different concentrations, valences, and sources of iron.

Drinking water can contain high concentrations of Fe, mainly of the ferrous (Fe(2+)) valence. The current recommended upper tolerable concentration of Fe in drinking water for cattle (0.3mg/L) comes from guidelines for human palatability, but cattle may be able to tolerate higher concentrations.

Enteric methane emissions and lactational performance of Holstein cows fed different concentrations of coconut oil.

To determine if dietary medium-chain fatty acids (FA; C(8) to C(14)) may mitigate enteric methane emissions, 24 cows were blocked by body size (n=2) and randomly assigned to 1 sequence of dietary treatments. Diets were fed for 35 d each in 2 consecutive periods. Diets differed in concentrations of coconut oil (CNO; ~75% medium-chain FA): 0.

Comparison of effects of dietary coconut oil and animal fat blend on lactational performance of Holstein cows fed a high-starch diet.

Dietary medium-chain fatty acids (C(8:0) through C(12:0)) are researched for their potential to reduce enteric methane emissions and to increase N utilization efficiency in ruminants. We aimed to 1) compare coconut oil (CNO; ~60% medium-chain fatty acids) with a source of long-chain fatty acids (animal fat blend; AFB) on lactational responses in a high-starch diet and 2) determine the effect of different dietary concentrations of CNO on dry matter intake (DMI). In experiment 1, the control diet (CTRL) contained (dry basis) 40% forage (71% corn silage, and alfalfa hay and haylage), 26% NDF, and 35% starch.

Dietary protein quality and quantity affect lactational responses to corn distillers grains: a meta-analysis.

Diet fermentability influences lactational responses to feeding corn distillers grains (CDG) to dairy cows. However, some measures of diet fermentability are inherently related to the concentration and characteristics of corn-based ingredients in the ration. Corn-based feeds have poor protein quality, unable to meet the essential AA requirements of lactating cows.

Diet fermentability influences lactational performance responses to corn distillers grains: a meta-analysis.

Increasing supply of corn distillers grains (CDG) raises questions about the extent to which they can be used in diets of lactating dairy cows. A database of treatment means (n=44) reported in 16 peer-reviewed journal articles published from 1985 to 2008 was developed. The database included response (within study) to a CDG diet compared with the control (no CDG) for milk yield (MY), milk fat concentration and yield, CDG content of the diet, and dietary composition of control and CDG diets (% of dietary dry matter).

Evaluating estimates of phosphorus maintenance requirement of lactating Holstein cows with different dry matter intakes.

The objective was to evaluate estimates of the inevitable fecal loss component of the P maintenance requirement of lactating Holstein cows consuming differing amounts of a low-P diet. The maintenance requirement for P is the sum of inevitable (e.g.

Exercise training of late-pregnant and nonpregnant dairy cows affects physical fitness and acid-base homeostasis.

The objective was to determine if exercise training improves physical fitness of nonlactating, late-pregnant and nonpregnant multiparous Holstein cows and alters acid-base homeostasis during an exercise test on a treadmill. Twenty-six pairs (each pair having 1 late-pregnant and 1 nonpregnant) of cows were assigned to treatments of exercise training or no exercise. Exercise training was walking (1.

Periparturient responses of multiparous Holstein cows fed different dietary phosphorus concentrations prepartum.

Our objective was to compare the effects of different prepartum dietary phosphorus concentrations on periparturient metabolism and performance. Forty-two late pregnant multiparous Holstein cows were fed 0.21, 0.

A system to assess fitness of dairy cows responding to exercise training.

Objectives were to develop a system to administer exercise training to dairy cows, to measure potential physiological indicators of fitness, and to assess physical fitness. Nonlactating, nonpregnant multiparous Holstein cows (n = 19) were in one of three exercise training treatments: no exercise; 1-h exercise; or 2-h exercise by walking 3 km/h every other day for 60 d in a mechanical walker. Treadmill tests on d 15, 30, 45, and 60 consisted of walking (5 km/h) with 1.

A partnership of universities and agri-business for an effective dairy herd management learning experience for undergraduates: the Dairy Challenge.

The Dairy Challenge contest allows undergraduate students to apply knowledge gained in the classroom in an evaluation of the management practices of commercial dairy farms. University faculty partnered with industry representatives to develop the competition. Participants in the Dairy Challenge do the following: 1) critically evaluate dairy herd management practices and make recommendations for improvements; 2) visit local dairy farms and gain knowledge of different farms' management practices; 3) meet and interact with potential employers from the dairy industry during the contest; 4) evaluate herd records and utilize knowledge of dairy herd management software and computer presentation tools; 5) test their speaking, presentation, and problem-solving skills; and 6) work as a team to build consensus and tag-team speaking formats.

Predicting average feed intake of lactating Holstein cows fed totally mixed rations.

A dry matter intake (DMI) prediction equation was estimated by using a data file that contained 124 treatment means collected from published studies. Animal factors considered for inclusion in the prediction model were body weight (BW) and its natural logarithm, BW(0.75), milk yield (MY) and its natural logarithm, milk fat and protein yields, month of lactation and its square, as well as its natural logarithm.

Peripartum responses of dairy cows fed energy-dense diets for 3 or 6 weeks prepartum.

Pregnant cows (n = 189) in two commercial dairy farms were assigned randomly to be fed energy-dense diets for either 3 or 6 wk before expected calving. Cows fed diets for less than or equal to 26 d were designated the short (S) treatment group, and those fed greater than 26 d were the long (L) treatment group. Cows in L tended to have improved energy status during the first 2 wk postpartum, as indicated by higher insulin concentrations and a tendency for lower nonesterified fatty acid concentrations.

Peripartum responses of dairy cows to partial substitution of corn silage with corn grain in diets fed during the late dry period.

We randomly assigned 189 cows in a commercial dairy farm to dietary treatments with supplemental corn grain (SC) or without supplemental corn grain (NC) approximately 3 wk before expected parturition. Diets formulated were similar except that dry ground corn replaced 21% of the corn silage in one diet. Cows fed SC had reduced plasma beta-hydroxybutyrate and tended to have increased plasma insulin concentrations prepartum compared with cows fed NC.

Effects of altering dietary cation-anion difference on calcium and energy metabolism in peripartum cows.

Our objective was to determine the effects of varying dietary cation-anion differences (DCAD: meq[(Na + K) - (Cl + S)]/100 g of dry matter) in prepartum diets on Ca, energy, and endocrine status prepartum and postpartum. Holstein cows (n = 21) and heifers (n = 34) were fed diets with varying amounts of CaCl2, CaSO4, and MgSO4 to achieve a DCAD of +15 (control), 0, or -15 meq/100 g of dry matter for the last 24 d before expected calving. Dietary Ca concentration was increased (by CaCO3 supplementation) with decreasing DCAD.

Responses of lactating dairy cows to copper source, supplementation rate, and dietary antagonist (iron).

Forty-eight lactating Holstein cows were fed low-Cu diets with 500 mg of supplemental Fe/kg of dry matter (DM), a Cu antagonist, for a 30-d Cu-depletion period. After depletion, two Fe treatments (0 and 500 mg of Fe/kg of dietary DM) and five Cu treatments (2 x 5 factorial arrangement) were compared over 83 d. The Cu treatments were control (basal diet containing 8 mg of Cu/kg of DM) and either 15 or 30 mg of supplemental Cu/kg of dietary DM from either CuSO4 or Cu-lysine.

Effects of inclusion of a blended protein product in 35 dairy herds in five regions of the country.

We assessed the change in milk production in 35 dairy herds located in eight states when a blended animal-marine protein product was included in diets at 2 (22 herds) to 4% (13 herds) of dry matter. Average 305-d production across herds was 8844.1 kg (SEM = 153.

A method to analyze production responses in dairy herds.

Milk production was simulated in a 50-cow herd averaging 8182 kg of 305-d milk with a standard deviation of 1364 kg. Herd demographics were 35% first lactation, 20% second lactation, and 45% third or greater lactation cows. A lactation model was developed with the Wood's equation (Milk/d = A*DIM*e(-c*dim)) to which random variation was added to be consistent with a coefficient of variation of 10% for daily milk production.

Effects of diet and injection of bovine somatotropin on prepubertal growth and first-lactation milk yields of Holstein cows.

To determine effects of rapid prepubertal growth on first-lactation milk production, Holstein heifers were randomly assigned to one of three treatments. Thirty-five heifers were fed a standard diet to meet NRC recommendations and produce 0.8 kg of body weight (BW) gain/d (standard).

Dietary mixtures of sodium bicarbonate, sodium chloride, and potassium chloride: effects on lactational performance, acid-base status, and mineral metabolism of Holstein cows.

The objective of this study was to determine lactational, blood mineral, and blood acid-base responses to dietary mixtures of NaHCO3, NaCl, and KCl and dietary cation-anion difference by lactating diary cows. Three 100:0:0 (primary) blends, three 50:50:0 (binary) blends, and one 33:33:33 (tertiary) blend of NaHCO3, NaCl, and KCl, respectively, were formulated to replace 1% of the dry matter in a diet based on corn silage. Seven treatments were defined according to a simplex-centroid mixtures design using a partially balanced incomplete block arrangement.

Evaluation of equations based on animal factors to predict intake of lactating Holstein cows.

The accuracy of seven DMI prediction equations based only on animal factors was evaluated with 11 independent data files. Mean square prediction error was used to compare equation accuracy, which was considered to be unsatisfactory when the square root of the mean square prediction error was greater than +/-20% of the observed mean DMI. Robust intake equations that have a tolerable level of prediction errors for most data files would be less risky for practical use than models that are highly accurate for some data files but highly inaccurate for others.

Macromineral element interrelationships and lactational performance: empirical models from a large data set.

The objectives were to model empirical interrelationships among dietary macromineral elements and cation-anion difference influencing DMI, milk yield, 4% FCM yield, and milk composition of dairy cows. The database consisted of 1022 cow-period means collected from 326 midlactation cows in experiments with incomplete block designs. Dietary concentrations of elements ranged from below to above current recommendations, and cation-anion difference (Na + K-Cl) was from +5.