Supplementation of Lysine and Methionine in Milk Replacer or Starter Concentrate for Dairy Calves in Step-Up/Step-Down Feeding Program

This study aimed to evaluate the performance and metabolic changes in dairy calves fed in a step-up/step-down program and supplemented with lysine and methionine in a milk replacer (MR) or starter concentrate (SC). Male Holstein calves (n = 45) were blocked and distributed in the control without supplementation (1) and with lysine and methionine supplementation in the SC to achieve an intake of 17 and 5.3 g/d, respectively (2), and in the MR to achieve the same daily intake (3). MR was fed 4 L/d until the 2nd week, 8 L/d from the 3rd to 6th week, and 4 L/d from the 7th to 8th week, when calves were weaned. The calves were followed until the 10th week of age. Feed intake was measured daily. Weight and body measurements were registered weekly, and blood samples were collected biweekly. The lysine and methionine intake during the whole period was higher when supplementation occurred via MR. There was a supplementation effect for average daily gain after weaning, and the animals supplemented in the MR had lower BW than those that were not supplemented. Supplementation in MR decreased starter intake at the 10th week and total intake (g DM/d) after weaning. Supplementation with lysine and methionine in the MR or the SC did not benefit the performance or metabolism of dairy calves in the step-up/step-down program. Further studies are needed to understand the effects of amino acid supplementation on feed intake.

Using compositional mixed-effects models to evaluate responses to amino acid supplementation in milk replacers for calves

The consequences of supplementing Lys, Met, and Thr in milk replacers (MR) for calves have been widely studied, but scarce information exists about potential roles of other AA (whether essential or not). The effects on growth performance of supplementation of 4 different AA combinations in a mixed ration (25.4% crude protein and 20.3% fat) based on skim milk powder and whey protein concentrate were evaluated in 76 Holstein male calves (3 ± 1.7 d old). The 4 MR were as follows: CTRL with no AA supplementation; PG, supplying additional 0.3% Pro and 0.1% Gly; FY, supplying additional 0.2% Phe and 0.2% Tyr; and KMT, providing additional 0.62% Lys, 0.22% Met, and 0.61% Thr. All calves were fed the same milk allowance program and were weaned at 56 d of study. Concentrate intake was limited to minimize interference of potential differences in solid feed intake among treatments. Animals were weighed weekly, intakes recorded daily, and blood samples obtained at 2, 5, and 7 wk of study to determine serum urea and plasma AA concentrations. Plasma AA concentrations were explored using compositional data analysis, and their isometric log-ratio transformations were used to analyze their potential influence on ADG and serum urea concentration using a linear mixed-effects model. We detected no differences in calf performance and feed intake. Plasma relative concentration of the AA supplemented in the KMT and PG treatments increased in their respective treatments, and, in PG calves, a slight increase in the proportion of plasma Gly, Glu, and branched-chain AA was also observed. The proportions of plasma branched-chain AA, His, and Gln increased, and those of Thr, Arg, Lys, and Glu decreased with calves' age. A specific log-contrast balance formed by Arg, Thr, and Lys was found to be the main driver for lowering serum urea concentrations and increasing calf growth. The use of compositional mixed-effects models identified a cluster formed by the combination of Arg, Thr, and Lys, as a potential AA to optimize calf growth.

Lysine and Methionine Supplementation for Dairy Calves Is More Accurate through the Liquid than the Solid Diet

This study aimed to evaluate the performance and metabolic changes in dairy calves supplemented with lysine and methionine in milk replacer (MR) or starter concentrate (SC). Male Holstein calves (n = 45) were blocked and distributed in Control without supplementation (1) and; Lysine and Methionine supplementation to achieve an intake of 17 and 5.3 g/d in the SC (2) and to achieve of 17 and 5.3 g/d in the MR (3). MR was fed (6 L/d) until the 8th week of life when weaning occurred. Calves were followed until the 10th week of age. Feed intake was measured daily. Weight and body measurements were registered weekly. Blood samples were collected biweekly to evaluate the intermediate metabolism. The AA supplementation resulted in lower body weight at weaning and week 10. Calves fed SC Lys:Met had lower SC intake and lower total feed intake at weaning when compared to control. Calves fed control had higher heart girth, hip-width, and plasma glucose concentration. The supplementation with Lys and Met did not benefit dairy calves' performance nor metabolism in this study. Supplementation through the MR was more efficient than SC to result in adequate daily intakes of AA. Further studies are needed to understand the negative effects of AA on calf starter intake.

Effects of different types of zinc supplement on the growth, incidence of diarrhea, immune function, and rectal microbiota of newborn dairy calves

Neonatal diarrhea in dairy calves causes huge economic and productivity losses in the dairy industry. Zinc is an effective anti-diarrheal agent, but high doses may pose a threat to the environment. Therefore, we aimed to evaluate the effects of low-dose zinc supplementation on the growth, incidence of diarrhea, immune function, and rectal microbiota of newborn Holstein dairy calves. Thirty newborn calves were allocated to either a control group (without extra zinc supplementation), or groups supplemented with either 104 mg of zinc oxide (ZnO, equivalent to 80 mg of zinc/d) or 457 mg of zinc methionine (Zn-Met, equivalent to 80 mg of zinc/d) and studied them for 14 d. The rectal contents were sampled on d 1, 3, 7, and 14, and blood samples were collected at the end of the study. Supplementation with ZnO reduced the incidence of diarrhea during the first 3 d of life, and increased serum IgG and IgM concentrations. The Zn-Met supplementation increased growth performance and reduced the incidence of diarrhea during the first 14 d after birth. The results of fecal microbiota analysis showed that Firmicutes and Proteobacteria were the predominant phyla, and Escherichia and Bacteroides were the dominant genera in the recta of the calves. As the calves grew older, rectal microbial diversity and composition significantly evolved. In addition, dietary supplementation with ZnO reduced the relative abundance of Proteobacteria in 1-d-old calves, and increased that of Bacteroidetes, Lactobacillus, and Faecalibacterium in 7-d-old calves, compared with the control group. Supplementation with Zn-Met increased the relative abundance of the phylum Actinobacteria and the genera Faecalibacterium and Collinsella on d 7, and that of the genus Ruminococcus after 2 wk, compared with the control group. Thus, the rectal microbial composition was not affected by zinc supplementation but significantly evolved during the calves' early life. Zinc supplementation reduced the incidence of diarrhea in young calves. In view of their differing effects, we recommend ZnO supplementation for dairy calves during their first 3 d of life and Zn-Met supplementation for the subsequent period. These findings suggest that zinc supplementation may be an alternative to antibacterial agents for the treatment of newborn calf diarrhea.

Effects of linseed oil and rumen undegradable protein:rumen degradable protein ratio on performance of Holstein dairy calves

The present study evaluated the interaction effects of n-3 fatty acids (from linseed oil (LSO), 0 v. 2·5, % DM basis) with rumen undegradable:degradable protein (RUP:RDP) ratios (low ratio (LR) 27:73; high ratio (HR) 38:62 based on crude protein %) in dairy calves' starter diet. Forty-eight 3-d-old female Holstein dairy calves (41·5 kg of body weight (BW)) were allocated in a 2 × 2 factorial arrangements in the following treatments (n 12 calves/each): (1) no supplementation of LSO with LR (NLSO-LR); (2) no supplementation of LSO with HR (NLSO-HR); (3) supplementation of LSO with LR (LSO-LR) and (4) supplementation of LSO with HR (LSO-HR). The calves were weaned on day 53 of the experiment and remained in the study until day 73. Intake was not affected by LSO and RUP:RDP ratio. However, average daily gain (ADG) was improved with LSO supplementation. Feeding the HR diet increased ADG compared with the LR diet during the entire period. Final BW was greater in calves fed on the LSO than those fed the NLSO diet. Microbial protein production did not differ among treatments. Calves fed on LSO diets had greater feed efficiency than those which were not fed on LSO diets. The calves supplemented with LSO had greater wither and hip heights compared with the unsupplemented calves. The glucose, cholesterol, HDL and insulin concentrations increased in calves supplemented with LSO. In conclusion, the HR diet improved calves' performance post-weaning; however, LSO could enhance growth performance of dairy calves during the pre-weaning period.

Determination of macromineral requirements for preweaned dairy calves in tropical conditions

International committees that have published nutrient requirements for dairy cattle have used data from mineral studies conducted in the 1920s to 1970s, and no study has reported data from animals less than 100 kg; therefore, there is a need to update mineral requirements for preweaned dairy calves. Thus, a meta-analysis was performed to estimate the mineral requirements of Ca, P, K, Mg, and Na for Holstein and Holstein × Gyr crossbred preweaned dairy calves using data from 5 studies developed at the Universidade Federal de Viçosa (Viçosa, MG, Brazil). A total of 210 calves were separated into 2 breeds: purebred Holstein calves (animals with a Holstein pedigree higher than 87.5%) and Holstein × Gyr crossbred calves (animals with a Holstein pedigree lower than 87.5%). The comparative slaughter technique was used to estimate animal body composition and empty body weight (EBW). Mineral requirements for maintenance were estimated by the regression between retained mineral and mineral intake, whereas mineral requirements for gain were obtained from the first derivative of the mineral content in the animal's body. In addition, breed effect was tested on the intercept and slope of the models. The effect of breed was not observed for all analyzed variables. Thus, net requirements for maintenance were 12.73, 11.81, 20.28, 3.50, and 6.37 mg/kg of EBW per day for Ca, P, K, Mg, and Na, respectively. Retention coefficients were 73.18, 65.20, 13.16, 29.55, and 24.28% for Ca, P, K, Mg, and Na, respectively. The following equations were determined to estimate net requirements for gain (NRG, g/d): NRG for Ca = 14.402 × EBW^-0.139 × empty body gain (EBG); NRG for P = 5.849 × EBW^-0.027 × EBG; NRG for K = 1.140 × EBW^-0.048 × EBG; NRG for Mg = 0.603 × EBW^-0.036 × EBG; and NRG for Na = 1.508 × EBW^-0.045 × EBG. Due to the high variation between the data found in this study and in the available literature, we suggest that further studies should be conducted to evaluate the estimates of this study.