M. Khorvash

Chromium supplementation and substitution of barley grain with corn: Effects on performance and lactation in periparturient dairy cows.

Thirty-two multiparous Holstein cows were used to investigate the effects of chromium-l-methionine (Cr-Met) supplementation and dietary grain source on performance and lactation during the periparturient period. Cows were fed a total mixed ration consisting of either a barley-based diet (BBD) or a corn-based diet (CBD) from 21 d before anticipated calving through 28 d after calving. The Cr-Met was supplemented at dosages of 0 or 0.08 mg of Cr/kg of metabolic body weight. The study was designed as a randomized complete block design with 2 (Cr-Met levels) x 2 (grain sources) factorial arrangement. There was no Cr effect on prepartum dry matter intake (DMI) or postpartum DMI, body weight (BW), net energy balance, and whole tract apparent digestibility of nutrients. Prepartum DMI as a percentage of BW tended to increase with Cr-Met. Supplemental Cr-Met tended to increase milk yield whereas milk protein percentage decreased. Pre- and postpartum DMI, BW, net energy balance, milk yield, and milk composition were not affected by substituting ground barley with ground corn. The addition of Cr-Met increased prepartum DMI and tended to increase postpartum DMI of the BBD but not the CBD. The change in prepartum DMI was smaller when the BBD was supplemented with Cr-Met but remained unchanged when the CBD was supplemented with Cr-Met. Yields of crude protein and total solids in milk and prepartum digestibility of DM and organic matter tended to increase when Cr-Met was added to the BBD but remained unchanged when added to the CBD. Periparturient cows failed to respond to the grain source of the diet, whereas they showed greater response in milk yield to diets supplemented with Cr-Met. In conclusion, the present results demonstrate that the beneficial effect of Cr-Met supplementation during the periparturient period to improve feed intake may depend on the grain source of the diet.

Interactions of alfalfa hay and sodium propionate on dairy calf performance and rumen development

The objective of this experiment was to investigate the effects of different levels of alfalfa hay (AH) and sodium propionate (Pro) added to starter diets of Holstein calves on growth performance, rumen fermentation characteristics, and rumen development. Forty-two male Holstein calves (40±2kg of birth weight) were used in a complete randomized design with a 3×2 factorial arrangement of treatments. Dietary treatments were as follows: (1) control = concentrate only; (2) Pro = concentrate with 5% sodium propionate [dry matter (DM) basis]; (3) 5% AH = concentrate + 5% alfalfa hay (DM basis); (4) 5% AH + Pro = concentrate + 5% alfalfa hay + 5% sodium propionate (DM basis); (5) 10% AH = concentrate + 10% alfalfa hay (DM basis); and (6) 10% AH + Pro = concentrate + 10% alfalfa hay + 5% sodium propionate (DM basis). All calves were housed in individual pens bedded with sawdust until 10wk of age. They were given ad libitum access to water and starter throughout the experiment and were fed 2L of milk twice daily. Dry matter intake was recorded daily and body weight weekly. Calves from the control, 10% AH, and 10% AH + Pro treatments were euthanized after wk 10, and rumen wall samples were collected. Feeding of forage was found to increase overall dry matter intake, average daily gain, and final weight; supplementing sodium propionate had no effect on these parameters. Calves consuming forage had lower feed efficiency than those on the Pro diet. Rumen fluid in calves consuming forage had higher pH and greater concentrations of total volatile fatty acids and molar acetate. Morphometric parameters of the rumen wall substantiated the effect of AH supplementation, as plaque formation decreased macroscopically. Overall, the interaction between forage and sodium propionate did not affect calf performance parameters measured at the end of the experiment. Furthermore, inclusion of AH in starter diets positively enhanced the growth performance of male Holstein calves and influenced both the macroscopic and microscopic appearances of the rumen wall. These benefits, however, were small when only sodium propionate was offered.

CORN SILAGE PARTIALLY REPLACING SHORT ALFALFA HAY TO OPTIMIZE FORAGE USE IN TOTAL MIXED RATIONS FOR LACTATING COWS

We theorized that adding corn silage to a total mixed ration with alfalfa hay as the sole dietary forage would improve nutrient intake and chewing activity and thereby improve rumen fermentation and milk production. The objective of this research was to determine the effects of partial replacement of short alfalfa [physically effective (pe) neutral detergent fiber (NDF) >1.18 mm (peNDF(>1.18)) = 33.2%] with corn silage (CS, peNDF(>1.18) = 51.9%) in yellow grease-supplemented total mixed rations on feed intake, chewing behavior, rumen fermentation, and lactation performance by dairy cows. Four multiparous (138 +/- 3 d in milk) and 4 primiparous (115 +/- 10 d in milk) Holstein cows were used in a 4 x 4 Latin square design experiment with four 21-d periods. Each period had 14 d of adaptation and 7 d of sampling, and parity was the square. Treatments were diets [dry matter (DM) basis] with 1) 40% alfalfa hay (ALF), 2) 24% alfalfa hay + 16% CS (CS40), 3) 20% alfalfa hay + 20% CS (CS50), and 4) 16% alfalfa hay + 24% CS (CS60). Diets had a forage-to-concentrate ratio of 40:60 on a DM basis. Cows had greater intake of DM and thus greater intakes of net energy for lactation, NDF, and peNDF when CS partially replaced alfalfa hay. Replacing alfalfa hay with CS increased daily eating and chewing times in all cows, and increased rumen pH at 4 h postfeeding in multiparous cows. Apparent total-tract digestibility coefficients for crude protein (CP) and NDF were not different among cows fed ALF, CS40, and CS50, but were lower for CS60 than for ALF. Energy-corrected milk yield was greater for CS40 and CS60 than for ALF. Milk protein yield was increased when CS replaced 40, 50, and 60% of alfalfa hay. Milk lactose was greater only for CS60, but milk lactose yield was greater for CS50 and CS60 than for ALF. Milk percentage and yield of fat did not differ among treatments. Therefore, CS partially replacing short alfalfa hay increased DM intake, consequently increased net energy for lactation and physically effective fiber intakes, and thus, improved milk and milk protein and lactose yields.

Chromium improves production and alters metabolism of early lactation cows in summer

Metabolic demands of early lactation introduce enormous challenges to dairy cows when coincided with environmental stresses. The objective of this study was to determine effects of a chromium (Cr) supplement on feed intake and blood indicators of nutrient metabolism in early lactation cows in summer. Fifteen Holstein cows at 38±6 days in milk were grouped based on parity and randomly assigned to three supplemental doses of 0, 0.05 and 0.10 mg Cr/kg of BW(0.75) . Cows received a basal mixed ration with a forage to concentrate ratio of 57.7:42.3, twice daily at 09:00 and 16:00 h for 9 weeks. The first 2 weeks were for adaptation, and the following 7 weeks were for weekly sampling and data collection. The Cr supplement (a Cr-methionine product with 10% Cr and 90% Met from a compound containing one atom of Cr and three molecules of Met) was mixed with 100 g of ground corn and top dressed with the morning feed. The average ambient temperature-humidity index was 77.7 units during the study. Dry matter intake increased from 21.8 to 24.2 and 23.7 kg/day when 0.05 and 0.10 mg Cr/kg BW(0.75) was provided respectively. Milk output of energy, fat, protein and total solids increased by providing Cr at 0.05 mg but not 0.10 mg/kg BW(0.75) . Both doses of Cr increased milk protein content, but the higher Cr dose reduced feed efficiency compared with control. While rectal temperature and body condition score were unaffected, cows receiving 0.05 mg and not 0.10 mg Cr/kg BW(0.75) tended to have greater respiration rate than control cows. Blood insulin and non-esterified fatty acids concentrations and the insulin to glucagon ratio decreased, and serum albumin increased when cows received 0.05 mg of Cr/kg BW(0.75) . Blood glucose, glucagon, insulin-like growth factor-1, total protein, globulins, urea, BHBA, triglycerides, cholesterol, cortisol, progesterone, and high- and very low-density lipoproteins were not affected. Therefore, supplemental Cr supply at 0.05 and 0.10 mg/kg BW(0.75) improved feed intake, only at 0.05 mg/kg BW(0.75) increased milk secretion, and mainly at 0.05 mg/kg BW(0.75) altered peripheral nutrient metabolism in early lactation Holstein cows under high ambient temperatures.

Grain source and marginal changes in forage particle size modulate digestive processes and nutrient intake of dairy cows

This study investigated the effects of, and interactions between, dietary grain source and marginal changes in alfalfa hay (AH) particle size (PS) on digestive processes of dairy cows. A total of eight Holstein dairy cows (175 days in milk) were allocated in a replicated 4 × 4 Latin square design with four 21-day periods. The experiment was a 2 × 2 factorial arrangement with two levels of theoretical PS of AH (fine = 15 mm or long = 30 mm) each combined with two different sources of cereal grains (barley grain alone or barley plus corn grain in a 50 : 50 ratio). Results showed that cows consuming diets supplemented with corn had greater dry matter and nutrient intakes (P < 0.01), independent of forage PS. In addition, the apparent digestibility of fiber fractions was greater for diets supplemented with corn (P = 0.01). The feeding of barley grain-based diets was associated with greater apparent digestibility of non-fiber carbohydrates, and this variable was even greater when long AH was fed (P = 0.04). Moreover, the feeding of long AH resulted in longer time spent eating (P = 0.03) and higher pH (P < 0.01), as well as a tendency for higher acetate-to-propionate ratio in the rumen fluid (P = 0.06) at 3 h post feeding. In conclusion, the results indicated that the marginal increase of PS of AH may prolong eating time and improve rumen fermentation, particularly in diets based on barley grain. Partial substitution of barley grain by corn can improve feed intake and fiber digestibility in mid-lactation dairy cows.

Physiological calf responses to increased chromium supply in summer

The primary objective was to determine pre- and postweaning calf physiological responses to increased Cr supply under high ambient temperatures. In a randomized complete block design, 24 neonate Holstein calves (BW=41.5+/-1.9 kg) were grouped based on sex and randomly assigned to 3 treatments within each group. Treatments included either no supplemental Cr (control), 0.02 mg of supplemental Cr/kg of BW0.75, or 0.04 mg of supplemental Cr/kg of BW0.75. The average temperature-humidity index was 77 during the study. Chromium was provided as a commercial product in whole milk for preweaning calves and in a starter concentrate for postweaning calves. Calves were weaned at 1 kg of daily calf starter intake lasting for 6 consecutive days. A glucose tolerance test was conducted on d 25 postweaning. Treatments had no effects on preweaning dry matter intake, feed conversion ratio, average daily gain, and weaning age. Chromium decreased dry matter intake in postweaning calves; however, it did not affect growth and feed conversion ratio. Chromium lowered respiration rate at wk 5 without affecting fecal score and rectal temperature. Preweaning serum cortisol concentrations were altered by a 3-way interaction of Cr dose with calf sex and age. Preweaning serum glucose showed week-dependent increases by Cr. Serum insulin, urea, albumin, total protein, triiodothyronine, and thyroxin concentrations through weaning were not affected. The increasing Cr doses caused quadratic declines in serum thyroxin on d 21 postweaning, whereas blood triiodothyronine declined only with the higher Cr dose. Serum NEFA remained unchanged, but BHBA decreased by Cr in male calves on d 21 postweaning. The glucose tolerance test revealed linear reductions in area under insulin curve between 0 to 90 and 0 to 120 min after glucose infusion, suggesting improvements in peripheral insulin efficiency. Sex-dependent responses to Cr were observed for serum total protein and albumin concentrations at 21 d postweaning. Overall, results indicate that in summer, increased dietary Cr supply can benefit postweaning insulin metabolism, alter preweaning blood cortisol and glucose levels, and reduce respiration rate and may have only minor effects on calf growth.

Short communication: Effects of dietary fat supplements and forage:concentrate ratio on feed intake, feeding, and chewing behavior of Holstein dairy cows

Feed intake and feeding behavior of dairy cows fed diets that varied in fat supplementation and forage:concentrate (F:C) ratio were investigated. Eight multiparous Holstein dairy cows were used in a replicated 4x4 Latin square experiment with 21-d periods. Treatments were 1) no supplemental fat and 34:66 F:C ratio; 2) 2% hydrogenated palm oil and 34:66 F:C ratio; 3) 2% yellow grease and 34:66 F:C ratio; and 4) 2% yellow grease and 45:55 F:C ratio. Cows were fed ad libitum twice daily as total mixed ration with free access to water. Dry matter intake (DMI) was not affected by fat supplementation regardless of fat source, whereas increased F:C ratio (from 34:66 to 45:55) lowered DMI by 7.5%. Meal interval, eating rate, and meal size were lower for cows fed yellow grease, and eating rate was less for cows fed the 45:55 F:C ratio diet. Chewing activity was not affected by fat supplementation, but was greater for cows fed the 45:55 F:C ratio diet. Results suggest that supplementation of 2% hydrogenated palm oil or 2% yellow grease had little effect on DMI and chewing behavior of Holstein dairy cows fed a 34:66 F:C ratio diet. The 2 fat sources can replace each other, depending on the availability or cost. Results also showed that DMI and chewing activity can be effectively manipulated by changing the F:C ratio of diet.

Use of absorbants and inoculants to enhance the quality of corn silage

This study examined whether inoculants and various absorbent materials could be used during ensiling to reduce effluent losses and improve nutritive value of corn silage. Two corn forages were harvested: conventional silage containing 29% dry matter (DM) and low DM silage containing 20% DM. Ninety-six mini-silos (10 cm × 1 m) were each prepared using 2.7 kg of chopped corn forage and one of the following compounds and add rates (fresh basis): no additive (control); 5, 10 or 15% ground barley; 5, 10 or 15% powdered whey; 5, 10 or 15% dried molasses; 1% bentonite; 1% zeolite; 0.5% zeolite plus 0.5% limestone; commercial inoculant containing Lactobacillus plantarum and Propionic bacteria sp. (Biotal™, Lallemand Animal Nutrition, Rexdale, ON; 2 mg kg-1 fresh forage); commercial inoculant containing Lactobacillus plantarum and Pediococcus acidilactici (Feedtech™, DeLaval, Tumba, Sweden; 24 mg kg-1 fresh forage ); and 1% zeolite plus Biotal inoculant. Effluent loss from the control low DM silage was high (74 mL...

Effects of the step-up/step-down and step-down milk feeding procedures on the performance, structural growth, and blood metabolites of Holstein dairy calves.

The objective of this study was to compare the efficacy of the step-up/step-down (SUSD) and step-down (STP) methods of milk feeding on the performance, growth parameters, blood metabolites, and health of dairy calves. For this purpose, 45 Holstein male calves (3d of age and 41 ± 3 kg of body weight) were randomly assigned to one of the following milk feeding groups: (1) conventional (CONV; 4 L/d milk from d 1 to 52, and 2 L/d milk from d 53 to 56 of the study), (2) STP (6 L/d milk from d 1 to 29, and 4 L/d milk from d 30 to 45 of the study followed by feeding 2L/d milk from d 46 to 56 of the study), and (3) SUSD (6 L/d milk from d 1 to 5, 8 L/d milk from d 6 to 15, 10 L/d milk from d 16 to 35, 8L/d milk from d 36 to 42, 6 L/d milk from d 43 to 47, 4 L/d milk from d 48 to 52 of the study followed by feeding 2 L/d milk from d 53 to 56 of the study). Calves were weaned on d 56 and followed until d 70 of the study period. Animals had ad libitum access to the same starter ration during the entire study period (d 3 to 70). Starter intake, total dry matter intake, and average daily gain were greater in the SUSD calves than those in the CONV and STP treatments during the preweaning period. The SUSD procedure was found to increase body weight during the entire study and improved body length, wither height, heart girth, hip height, and hip width on d 56 and 70 of the study compared with the STP and CONV calves. The SUSD treatment increased blood glucose concentration on d 35 compared with CONV and STP procedures. The STP group had a higher starter intake than the CONV and SUSD animals. The STP animals exhibited a higher plasma concentration of total protein and BHBA than did the SUSD animals during the preweaning period. Neither the SUSD nor the STP procedure negatively affected the fecal score. In conclusion, the SUSD milk feeding procedure was found to improve the performance of dairy calves compared with the STP and CONV procedures. However, it appears that the STP procedure induces earlier reticulo-rumen developement in dairy calves than does the SUSD procedure.

The effect of restricted milk feeding through conventional or step-down methods with or without forage provision in starter feed on performance of Holstein bull calves.

The objective of the current study was to examine whether step-down (STP) milk feeding method together with forage provision would improve performance, rumen fermentation, nutrient digestibility, blood metabolites, and structural growth of calves. Holstein bull calves ( = 40) were randomly assigned to 1 of 4 treatments in a completely randomized design with a 2 × 2 factorial arrangement. Treatments were 1) conventional (COV) milk feeding without forage provision (COV-NF), 2) COV milk feeding with forage provision, 3) STP milk feeding without forage provision, and 4) STP milk feeding with forage provision. Calves in the COV method ( = 20) received 5.5 L/d milk until d 56 of age followed by 2 L/d milk from d 56 to 59 of age. Calves in the STP method ( = 20) received 7 L/d milk until d 35, 4 L/d milk from d 35 to 48, and 2 L/d milk from d 50 to 59 of age. All the calves received the starter ration from d 3 of the study until d 74 of age. Forage-supplemented calves ( = 10/milk feeding method) received 15% alfalfa hay mixed with finely ground starter as a total mixed ration. All calves were weaned on d 60 of age and remained in the study until d 74. Regardless of the milk feeding method, the final BW (92.54 vs. 83.14 kg/d), starter intake (0.90 vs. 0.65 kg/d), total DMI (1.43 vs. 1.17 kg/d), and ADG (0.73 vs. 0.60 kg/d) were greater ( < 0.01) in forage-supplemented calves than those that received no forage during the preweaning, postweaning, and overall periods. Milk feeding method had no effect on ruminal pH, total VFA, acetate, or acetate:propionate ratio as well as body measurements. Ruminal pH and the molar proportions of acetate were greater ( < 0.05) in the forage-supplemented calves than those that received no forage during the pre- and postweaning periods. Regardless of forage provision, STP methods increased ( < 0.05) the postweaning numbers of monocytes and lymphocytes. Overall, there was no interaction between milk feeding methods and forage provision with respect to BW, DMI, G:F, apparent nutrient digestibility (DM, OM, and CP), and body measurements. The interaction of milk feeding method and forage provision was significant for the rumen concentration of butyrate ( < 0.05), with the highest concentration for the COV-NF treatment on d 35 of the study. In conclusion, independent of the milk feeding method, inclusion of 15% alfalfa hay in starter diets enhances the performance of dairy calves.