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.

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The objective of this study was to investigate the effect of feeding different levels of ruminally protected methionine and choline on the incidence of physiological and metabolic disorders, production, and some of the reproductive indices of Holstein dairy cows. Forty Holstein dairy cows in their first and second lactation were used from 4-week pre-partum through 20-week post-partum and randomly assigned to receive one of the following treatments: 18 g/day of rumen-protected methionine (RPM), 60 g/day of rumen-protected choline (RPC), 18 g/day of RPM + 60 g/day of RPC, and neither supplement (control). The treatments significantly affected services per conception and open days of lactating dairy cows (p < 0.05), but did not affect significantly on days to first oestrus and number of pregnant cows. RPM + RPC-fed cows had the lowest open days, days to first oestrus and services per conception compared with other groups. The effect of treatments was significant on the incidence of metabolic and physiological problems except for foot/leg problems. Cows fed RPM+RPC had the lowest health problems compared with other groups (p < 0.05). Results indicate that the supplementation of RPM and RPC can improve reproductive performance and health status of dairy cows.

No abstract

Effects of live yeast supplementation on mid-lactation dairy cows performances, milk composition, rumen digestion and plasma metabolites during hot seasonFifty-six Holstein cows (36 multiparous and 20 primiparous), that averaged 145923 days postpartum, were used to investigate the supplementing of live yeast (LY) on productivity during hot summer conditions, from July until August 2010. Cows were fed a control diet with or without 4 g of LY (15 )10 9 CFU/g) per cow daily during a five-week period. Cows were milked three times a day and milk yield was recorded daily. Milk samples were also taken weekly for milk composition analysis. Blood samples and rumen liquor samples were taken in two subsequent days during the last week of the experiment. Milk production, 3.5% fat-corrected milk, and DM intake were similar for cows fed on both diets. A greater milk fat percentage was observed for cows fed LY compared to the control (PB0.05). However, milk urea nitrogen concentration in cows fed LY was lower compared to the control (PB0.01). Cows fed LY had greater blood glucose compared to the control (P B0.01). Blood urea nitrogen was lower for cows fed LY compared to the control (P B0.05). Non-esterified fatty acids, bhydroxybutyrate (BHB), triglyceride, total protein, and total cholesterol were similar for both diets. The apparent digestibility of NDF was greater for cows fed LY compared to the control (PB0.05). Rumen parameters such as pH, N-NH 3 , and VFAs were also similar for both treatments. The present results suggested that feeding LY to mid-lactation Holstein cows during heat stress can increase diet cell wall digestibility and improve milk fat percentage.

No abstract

An experiment was conducted to determine the effects of different milking frequencies on entire lactation production performance in Holstein cows. One hundred twenty Holstein cows were assigned to 3 milking treatments (35 multiparous and 5 primiparous cows in each): 1) milking 6 times daily for the entire lactation (6x); 2) milking 6 times daily for the first 90 d in milk (DIM) and switching to 3 times daily milking afterward (6x-3x); and 3) milking 3 times daily for the entire lactation (3x). Milk yield was recorded every other day during the first 60 DIM and on 2 consecutive days per week subsequently. Cows were weighed and scored for their body condition immediately after parturition and monthly afterward. Blood and milk samples were taken from each cow on 30, 60, 90, 120, 150, 210, and 270 DIM, with an additional blood sampling on 15 DIM. Milk and fat corrected milk yield was greater for 6x and 6x-3x cows than for 3x cows (36.82, 37.32, and 36.1, 36.75 versus 34.56, 35.33 kg/d, respectively) during the experimental period. Milk fat and lactose percentage were not different among treatments, but milk protein was lower in 6x cows than in 6x-3x and 3x cows. Blood glucose concentration was higher and blood nonesterified fatty acids and beta-hydroxybutyrate concentration were lower in 3x cows than in 6x and 6x-3x cows during early lactation. Dry matter intake was greater in 6x cows than in 6x-3x and 3x cows (23.05, 22.58, and 22.45 kg/d, respectively). The 3x cows began to gain weight earlier than the 6x and 6x-3x cows, but there was no difference among groups for BW change regarding the entire experimental period. These results indicate that increasing milking frequency to 6 times daily increases milk yield only during early lactation and that there are no advantages of milking 6 times daily compared with 3 times daily during the mid and late lactation periods. Given the results of this study and the economical aspects of production, milking 6 times daily until 90 DIM and subsequently switching to milking 3 times daily is preferred.

SUMMARYForty Holstein dairy cows in their first and second lactations were used from 4 weeks prepartum to 10 weeks postpartum to investigate the effects of feeding ruminally protected methionine and choline on plasma metabolites. Cows were randomly assigned to one of the following treatments in a 2×2 factorial design 4 weeks before their expected calving dates, using randomized blocks based on parity: no supplement (control), 18 g/d of rumen-protected methionine (RPM) product, 60 g/d of rumen-protected choline (RPC) product, or 18 g/d of RPM+60 g/d of RPC. Treatments did not affect plasma triglycerides, glucose, total protein, nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), plasma urea nitrogen (PUN) or aspartate aminotransferase (AST) during the prepartum period. For postpartum plasma NEFA concentrations, there were interactions between RPC or RPM and week postpartum. Feeding RPM increased plasma AST concentrations (P<0·05) and decreased plasma protein concentrations (P<0·05) in postpartum cows. After calving, feeding RPC increased (P<0·05) dry matter intake (DMI), milk yield, 40 g/kg fat-corrected milk (FCM) yield and energy-corrected milk (ECM) yield. This suggests that supplemental RPC can improve lactation performance of dairy cows.