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Feeding 56 versus 0 g/d of Saccharomyces cerevisiae fermentation product (SCFP; Diamond V Original XP; Diamond V, Cedar Rapids, IA) can increase feed intake and milk production in transition dairy cows. To evaluate the effects of various dosages of SCFP, Holstein cows were given individually a supplement containing 0 (n=14), 56 (n=15), or 112 g (n=13) of SCFP daily during morning lockup as a topdressing to their total mixed ration. The supplement consisted of 0, 56, or 112 g of SCFP mixed with 84 g of molasses and 168, 112, or 56 g of corn meal, respectively. Supplement feeding began 28 d before predicted calving date (no less than 14 d) and ended 28 d postpartum, and supplement intake was evaluated daily. Blood samples were collected at d -21, -14, -7, -3, -1, 0, 1, 3, 7, 14, 21, and 28 to measure serum concentrations of macrominerals, metabolites, acute-phase proteins, immunoglobulin, and hormones. Milk weights were measured and milk samples were collected 2 times/wk on nonconsecutive days and analyzed for milk fat, protein, lactose, and somatic cell count (SCC). During the first day after calving, feeding SCFP versus no SCFP decreased serum cortisol concentrations and at least tended to increase supplement intake and serum concentrations of calcium, glucose, urea N, and serum amyloid A. During the first 4 wk postpartum, feeding SCFP versus no SCFP decreased milk SCC and increased milk production and serum phosphorus concentrations. Feeding 112 versus 56 g of SCFP/d did not show additional effects. Feeding SCFP may have a dosage-independent beneficial effect in supporting the physiologic adaptations after parturition, resulting in higher milk production and lower milk SCC., (Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

The purpose of this study was to use meta-analytic methods to estimate the effect of a commercially available yeast culture product on milk production and other production measures in lactating dairy cows using a meta-analysis of randomized controlled trials. Sixty-one research publications (published journal articles, published abstracts, and technical reports) were identified through a review of literature provided by the manufacturer and a search of published literature using 6 search engines. Thirty-six separate studies with 69 comparisons met the criteria for inclusion in the meta-analysis. The fixed-effect meta-analysis showed substantial heterogeneity for milk yield, energy-corrected milk, 3.5% fat-corrected milk, milk fat yield, and milk protein yield. Sub-group analysis of the data showed much less heterogeneity in peer-reviewed studies versus non-peer-reviewed abstracts and technical reports, and tended to show higher, but not significantly different, treatment effects. A random-effects meta-analysis showed estimated raw mean differences between treated and untreated cattle reported in peer-reviewed publications of 1.18 kg/d [95% confidence interval (CI): 0.55 to 1.81], 1.61 kg/d (95% CI: 0.92 to 2.29), and 1.65 kg/d (95% CI: 0.97 to 2.34) for milk yield, 3.5% fat-corrected milk, and energy-corrected milk, respectively. Milk fat yield and milk protein yield for peer-reviewed studies showed an increase in the raw mean difference of 0.06 kg/d (95% CI: 0.01 to 0.10) and 0.03 kg/d (95% CI: 0.00 to 0.05), respectively. Estimated raw mean dry matter intake of the peer-reviewed studies during early lactation (<70 d in milk) and not-early lactation were 0.62 kg/d (95% CI: 0.21 to 1.02) and a decrease of 0.78 kg/d (95% CI: -1.36 to -0.21), respectively. These findings provide strong evidence that this commercially available yeast culture product provides significant improvement in several important milk production outcomes as evaluated in production settings typical for commercial dairies in North America. Utilizing meta-analytic methods to study the complete breadth of information relating to a specific treatment by studying multiple overcomes of all eligible studies can reduce the uncertainty often seen in small individual studies designed without sufficient power to detect differences in treatments., (Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Recent research has focused on the importance of supplying essential fatty acids to the lactating dairy cow. The addition of essential fatty acids, specifically linoleic and linolenic acid, to dairy cow diets has been investigated as a method to increase reproductive efficiency. Rumen bacteria, however, biohydrogenate polyunsaturated fatty acids (PUFA) to saturated fatty acids. This is an important issue because it can also lead to milk fat depression when unsaturated fatty acids are fed. The formation of Ca salts has previously been shown to partially protect unsaturated fatty acids from rumen biohydrogenation. The objective of this experiment was to evaluate feed intake, milk production, and milk composition of cows fed Ca salts of palm fatty acids (CS) compared with those fed Ca salts of palm fatty acids with an increased content of PUFA (CS+PUFA). Nineteen lactating Holstein cows were used in a switchback experiment to determine any differences between CS and CS+PUFA on milk production and composition. This experiment consisted of 3 consecutive periods of 14 d. Treatments were formulated to provide 450 g/d (dry matter basis) of the Ca salt supplement and were mixed with the same basal ration. Milk weights and feed intakes were recorded daily for each cow. Milk samples were collected the last 2 d of each period and analyzed for milk composition and fatty acids. Dry matter intake [28.0 vs. 27.0 kg/d; standard error of the mean (SEM) = 0.4] and milk production (44.4 vs. 44.0 kg/d; SEM = 0.7) were not different between treatments for CS and CS+PUFA, respectively. Milk fat percentage (3.34 vs. 3.22%; SEM = 0.07) and milk protein percentage (2.78 vs. 2.80%; SEM = 0.01) were not different for CS- and CS+PUFA-fed cows. Feeding CS+PUFA reduced the concentration of palmitic acid in milk fat (28.3 vs. 26.8 wt%; SEM = 0.3). Supplementation of CS+PUFA increased the linoleic acid concentration (3.96 vs. 4.61 wt%; SEM = 0.1) of milk fat, indicating that linoleic acid was partially protected from rumen biohydrogenation. Concentrations of conjugated linoleic acid were also increased (0.44 vs. 0.52 wt%; SEM = 0.02) when cows consumed CS+PUFA, indicating that some biohydrogenation did occur. Supplementing CS+PUFA did not alter milk production, milk fat percentage, or dry matter intake when compared with CS. The CS+PUFA supplement supplied more linoleic acid to the small intestine for milk fat synthesis.

In trial 1, 30 midlactation (213 d in milk) Holstein cows were randomly assigned to a control or enzyme treatment in a two-period crossover design and were fed a total mixed ration based on alfalfa hay and silage. Cows on the enzyme treatment received an enzyme solution containing cellulases and xylanases, which was sprayed on the forage component of the ration at a rate of 1.65 ml/kg of forage dry matter (DM) between 8 and 24 h prior to feeding. Cows consuming the forage treated with enzyme produced more milk (27.2 vs. 25.9 kg/d) and digested more DM per day than did cows fed the control forage. In trial 2, 40 early lactation Holstein cows were assigned to one of four treatments for 16 wk. Following a 2-wk covariate period, cows were assigned to 1) no enzyme treatment, 2) a low (1.25 ml/kg of forage DM) enzyme treatment, 3) a medium (2.5 ml/kg of forage DM) enzyme treatment, or 4) a high (5.0 ml/kg of forage DM) enzyme treatment. Enzymes were a 2:1 combination of cellulase and xylanase diluted in water and sprayed on a combination of alfalfa hay and silage and whole cottonseed immediately before mixing with a concentrate based on barley. Dry matter intakes were similar for cows on treatments 2, 3, and 4 and were greater than those for cows on treatment 1. Production of milk, 3.5% fat-corrected milk, and energy-corrected milk was greater for cows on treatment 3 than for cows on treatment 1. Fibrolytic enzymes applied to the forage portion of the rations prior to feeding improved lactational performance of early and midlactation cows.

This study compared prepartum diets based on grass, alfalfa, or alfalfa and anionic salts to investigate their effect on Ca metabolism, acid-base status, endocrine response, disease incidence, and lactational performance of periparturient dairy cows. Forty-five nonlactating Holstein cows in their last 3 wk of gestation were fed a control diet based on grass hay with a dietary cation-anion difference [expressed as milli-equivalents of ((Na + K) - (Cl + S))/100 g of dietary dry matter] of +30 or diets based on alfalfa with a dietary cation-anion difference of either +35 or -7. Cows fed the diet with the dietary cation-anion difference of -7 had the lowest urine pH prepartum and had the highest concentrations of ionized Ca in blood and total Ca in serum at parturition. Increases in 1,25-(OH)2 vitamin D per unit decrease in total Ca in serum were greatest for cows fed the diet with a dietary cation-anion difference of -7. Also, cows fed this same diet consumed the most dry matter postpartum. Incidences of health disorders were 13% (10 of 75), 12% (9 of 75), and 5% (4 of 75) for cows fed the diets with dietary cation-anion differences of +30, +35, and -7, respectively. Results indicate that alfalfa, when supplemented with anionic salts, is a viable forage for prepartum dairy 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. An eighth treatment served as a control and contained 1% SiO2 instead of the mineral blends. Dietary cation-anion difference ranged from +25 to +40 meq of (Na + K - Cl)/100 g of dietary dry matter. Diets were fed for three consecutive 28-d periods during summer to 36 midlactation cows. Cows that were fed the tertiary mixture had lower milk protein percentage, whole blood bicarbonate, and plasma K than did cows fed the other blends. With the exception of milk protein percentage and body weight gain, none of the mixtures had a significant impact on lactational performance. The lack of differences could have been due to the narrow range in the dietary cation-anion difference studied.

A study was conducted to examine the method of delivery of a solution containing cellulases and xylanases on the digestion of a forage-based diet. Five ruminally cannulated beef steers (536 kg BW) were randomly assigned to a control (CON) or one of four enzyme treatments in a 5 x 5 Latin square experiment. Steers were fed a 70:30 (DM basis) grass hay:barley diet. Enzyme-treated rations contained a solution of fibrolytic enzymes at the rate of 1.65 mL/kg of forage DM. Enzyme application treatments were 1) enzyme to forage 24 h before feeding (F-24), 2) enzyme to forage 0 h before feeding (F-0), 3) enzyme to barley 0 h before feeding (B-0), and 4) enzyme infused ruminally 2 h after feeding (RI). Dry matter and NDF intakes were not different (P > .10) across treatments. Ruminal pH was lower and total VFA concentration at 16 h after-feeding was greater (P < .10) for steers fed enzyme treatments compared with CON. Rate of NDF disappearance was greater (P < .05) for enzyme-treated than for untreated grass substrate. Ruminal infusion of enzymes compared with F-24 and F-0 produced lower disappearance of DM at 8 and 32 h (P < .10), NDF at 32 h (P < .10), and DM and NDF at 96 h (P < .05). Rate of DM disappearance of enzyme-treated grass hay was greater (P < .10) for steers fed B-0 than for those fed F-24 and F-0 and for CON than for F-24 and F-0. Total tract digestibility of DM, NDF, and ADF was greater (P < .10) for F-24 and F-0 than for CON. Forage transit time was shorter (P < .10) for B-0 than for F-24 and F-0; however, all other contrasts for particulate passage did not differ (P > .10). Results from this study indicate that direct application of enzymes to forages is capable of improving forage digestion.

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 +5.8 to +61.2 meq/100 g of dietary DM. Interrelationships were detected for dietary concentrations of Na by K for DMI, 4% FCM yield, and milk fat percentage; Na by Ca for DMI, milk yield, and 4% FCM yield; K by Cl for DMI, 4% FCM yield, and milk protein percentage; K by Ca for 4% FCM yield, milk protein, and fat percentages; Na and P for DMI and milk protein percentage; and K by P for 4% FCM yield and milk fat percentage. Maximal DMI and milk yield were observed with .58% Na, .40% Mg, and +38 meq/100 g of dietary DM. Agreement was close for DMI and milk yield responses to dietary cation-anion difference from our database and independent data sets. The models developed are empirical, do not necessarily establish cause and effect, and should be evaluated prudently; however, they provide useful information to design future research.

This paper examines whether or not responses of dairy cattle to various dietary macromineral elements differed in hot weather compared with thermoneutral conditions. The consequences of heat stress and the interrelationships of macromineral elements on feed intake, digestive function, use of dietary buffers, mineral element uptake from the portal-drained viscera, perturbation of acid-base physiology and related mineral element nutrition, effects of dietary macromineral element concentrations on lactational performance as affected by season, and influence of mineral elements in drinking water are reviewed, and new research results are presented. Dietary mineral buffers aided in alleviation of the decline in DMI and milk yield induced by heat stress. New research results showed that portal plasma flow declined with heat stress or by restriction of DMI in a thermoneutral environment and that uptake of P from the portal-drained viscera by lactating cows was reduced 50% by heat stress compared with that of cows with the same DMI in a thermoneutral environment. Accelerated respiration rate caused respiratory alkalosis and apparently compensated metabolic acidosis, changing the demand for Na and K during heat stress. There is need to characterize more accurately the nyctohemeral pattern of acid-base physiology in the heat-stressed lactating dairy cow and to relate it to macromineral element needs. A large data set (n = 1444 cow period means) was used to compare milk yield and DMI responses to varying dietary concentrations of P, Na, K, Cl, Ca, Mg, and cation-anion difference in summer compared with those in winter. Interactions of dietary concentrations of Cl, Ca, and Mg with season on DMI and K, Ca, and Mg with season on 4% FCM yield were detected. Interactions of Na by Cl, Na by P, and Cl by P with season on DMI and of Cl by P with season on 4% FCM yield were detected. High concentrations of sulfate and chloride in drinking water jeopardized productivity of cows during hot weather.

Objectives were to determine responses to graded dietary concentrations of Na, K, and Cl and to cation-anion difference. The design was a partially balanced incomplete block with 48 cows, four 28-d periods, and 15 treatments. Five concentrations each of Na, K, and Cl, ranging from .31 to .85%, .86 to 1.96%, and .32 to 1.15%, respectively, were fed in a TMR based on corn silage. Cation-anion difference (Na+K-Cl) ranged from +12 to +62 meq/100 g of dietary DM. Dry matter intake was affected by interactions between Na and K and between Na and Cl. Yield of 3.5% FCM increased as Na increased (independent of K and Cl concentrations); FCM yield response to dietary K depended on dietary Cl. Milk fat percentage responded quadratically to Na, K, and Cl. Milk fat percentage was maximum at .60% Na, 1.34% K, and .69% Cl. Dry matter intake, BW gain, and blood partial pressure of CO2 responded in a cubic fashion; FCM yield, milk protein percentage, and blood HCO3 concentrations responded quadratically; and blood base excess increased linearly with increasing cation-anion difference. Based on regression models, 3.5% FCM yield and DMI were highest when the cation-anion difference was between +30 and +50. These results indicate that interrelationships among Na, K, and Cl were abundant and were related to blood acid-base status and mineral element concentrations.

An experiment utilizing 391 preweaning and 187 postweaning litter records from 145 does was conducted for 12 mo to determine the effect of dietary crude protein level on performance of commercial New Zealand White rabbits. Does and their litters were fed alfalfa-based pelleted diets containing either 17.5, 19 or 20.5% crude protein (CP). In a separate experiment, the 17.5 and 20.5% CP diets were fed during lactation to 10 does to determine nitrogen (N) digestibility and retention. Body weights of does fed 17.5% CP were lower (P less than .01) than for the other treatments after 21 and 28 d of lactation. No differences (P greater than .10) were observed for doe weight at kindling, percentage fertility, litter size, preweaning litter mortality, 1- to 21-d consumption, preweaning feed efficiency and 28- to 56-d average daily consumption, average daily gain and average weight. Total born tended to be higher (P = .07) on higher protein levels but percentage born alive was greatest (P less than .01) on the 17.5% CP diet. Does fed 19% CP tended to have a greater number of parities (P = .06). Other significant differences observed for preweaning litter traits were between 17.5 and 19% CP groups. Does fed 19% CP had heavier litters at birth (P less than .01), at 21 d (P = .05) and 28 d (P = .06) and had greater 1- to 21-d litter gains and 21- to 28-d consumption (P = .05) than those fed 17.5% CP. For postweaning performance, feed efficiency values were lowest and mortality was highest for litters fed 20.5% CP. When litters were switched to different diets after weaning, mortality tended to be higher (P = .07) for animals that were fed 20.5% CP before weaning. The month of experiment effect did not influence any of the characters studied (P greater than .05). Parity number was important for percentage fertility, percentage born alive, litter birth weight and doe weight at 21 and 28 d (P less than .05). Does at first parity showed the poorest performance for all traits (except percentage fertility). Fertility fluctuated throughout the first four parities and then steadily declined. Does fed 20.5% CP had greater apparent dry matter and acid detergent fiber digestibilities and N intakes (P less than .05) and retained 90% more N during lactation (P = .22) than does fed 17.5% CP. Milk production and CP digestibility did not differ between the two diets tested.(ABSTRACT TRUNCATED AT 400 WORDS)