HERD MANAGEMENT

Calf Research Roundup: Highlights From The 2010 Dairy Science Meeting

08/17/2010 10:38AM

The annual meeting of the American Dairy Science Association was held in Denver, Co., in July. Scientists from all over the world presented their newest research findings, including many studies related to calves.

Colostrum and Passive Transfer
Research from the University of Florida (Perdomo and Santos) evaluated the relationships between serum IgG levels at 48 hours of age and calf performance through 70 days of age using 1034 male and female Holstein calves. All calves received 1.5 gallons of colostrum within 24 hours of birth. Calves were fed 1.5 gallons of pasteurized whole milk in three feedings per day through 21 days of age and 1 gallon in two feedings from 22 days through weaning at 60 days. Starter grain was available free-choice throughout the study. Calves were categorized as having adequate passive transfer or failure of passive transfer using a cutoff of 10 g/L of serum IgG; 5.6% of calves had failure of passive transfer. Mortality in the first 70 days of life was 20.7% in calves with failure of passive transfer compared to 5.7% in calves with serum IgG above 10 g/L.

Average daily gain was 0.62 lb/d in calves with adequate passive transfer compared to 0.37 lb/d in calves with failure of passive transfer during the first 30 days of life. Average daily gain from day 31 to 70 continued to be greater in calves with adequate passive transfer (1.52 vs. 1.37 lbs/d), and calves with adequate passive transfer weighed 6.8 lbs more at weaning than calves with failure of passive transfer (165.3 vs. 158.5 lbs). In addition, treatment costs were higher for calves with low serum IgG ($0.19/calf compared to $0.11/calf per day). More pneumonia was seen in calves with failure of passive transfer, but incidence of diarrhea and fever were similar between the two groups.

In another Florida study (Garcia et al.), fat supplementation during the dry period was investigated for effects on transfer of passive immunity to calves. Cows were fed a control diet with minimal linoleic acid and no supplemental fat, saturated fatty acids (1.75% of diet dry matter as Energy Booster 100) or calcium salts of unsaturated fatty acids (2% of diet dry matter as Megalac-R) for 60 days before calving. Calves received 1 gallon of colostrum from their dam or from another cow fed the same diet.

Fat supplementation increased colostrum IgG levels in multiparous cows (116 vs. 96 g/L), but the opposite occurred in first-lactation cows (83 vs. 101 g/L). Calves born to multiparous cows fed fat had higher IgG intake than calves from dams not fed fat. As a result, calves from multiparous cows fed fat tended to have higher IgG levels at 24 hours than calves from cows not fed fat (26.7 vs. 21.1 g/L) and tended to be more efficient at absorbing IgG (26.8 vs. 23.3%). Also, in a follow-up study, calves out of cows that had been fed saturated fatty acids during the dry period had 0.1 lb/d greater average daily gain during the preweaning period than calves out of cows fed unsaturated fatty acids.

Milk Replacer Formulation
New federal regulations concerning antibiotics in milk replacer took effect earlier this year, and two studies were presented that looked at the new feeding rates. Merrick’s and Animix researchers (Shields et al.) fed 1.25 lbs/d of 20% protein, 20% fat milk replacer and compared feeding the treatment rate of antibiotic (10 mg of neomycin and oxytetracycline per pound of body weight) for 14 days to feeding no antibiotic. Bull calves were purchased at auction, began the study at 3 to 5 days of age, and were weaned based on starter intake after 42 days on milk.

There was a tendency for fewer calves in the antibiotic-fed group to develop scours (55% vs. 86%), and on average, antibiotic-fed calves had 0.91 fewer days of treatment than control-fed calves. Calves fed antibiotic for the first 14 days of the trial had improved grain intake in weeks 2 and 4 and tended to have better grain intakes in weeks 1 and 3 and in total over the 8-week trial. Feed efficiency and average daily gain tended to be improved during the first 3 weeks of the trial for calves fed antibiotic. However, over the whole trial, weight gain and feed efficiency were higher in control-fed calves.

In a University of Minnesota study (Litherland et al.), heifer calves were fed a 20% protein, 20% fat milk replacer at 1.25 lbs/d for 35 days and half this amount from day 36 through 42. Antibiotic treatments were: 0 neomycin, 0 oxytetracycline for 42 days; 400 g/ton neomycin, 200 g/ton oxytetracycline for 42 days (old rate); 1600 g/ton neomycin, 1600 g/ton oxytetracycline (new rate) on days 1 to 14; or 1600 g/ton neomycin, 1600 g/ton oxytetracycline on days 1 to 14 and 16 to 28 (total of 26 days on antibiotics).

Calves fed no antibiotic had lower starter intake and average daily gains than those fed the old rate for 42 days or fed the new rate for 26 days. Calves fed no antibiotic had lower feed efficiency than all other treatments. Calves fed no antibiotic had fewer days of scouring than calves fed the new rate for 26 days. Daily costs of the antibiotic treatments were approximately 2, 4, and 6 cents/calf for the old rate, new rate for 14 days, and new rate for 26 days, respectively.

University of Florida researchers (Garcia et al.) reported that increasing the amount of linoleic acid in milk replacer improved calf performance. Calves received milk replacer only for the first 30 days of life and milk replacer plus starter from 31 to 60 days. Linoleic acid intake was 2.8 or 9.3 g/d for the first 30 days and 8.5 or 17.2 g/d from day 31 to day 60 (both groups consumed 4.8 g/d of linoleic acid in starter). Average daily gains in the first 30 days were 0.57 and 0.68 lb, a 19% improvement for calves fed more linoleic acid. Feed efficiency was 0.52 and 0.60, and calves fed more linoleic acid were 15% more efficient at converting feed to gain during the first 30 days of life. Over the course of 60 days, calves fed more linoleic acid maintained their advantage in average daily gain (0.98 vs. 1.10 lbs/d) and in feed efficiency (0.57 vs. 0.63).

Grain Composition and Intake
Data from 20 trials conducted at the Nurture Research Center (formerly Akey) were combined for a meta-analysis and used to develop a model to predict growth in calves up to 8 weeks of age (Bateman et al.). Of all the factors considered, starter intake was the strongest predictor of average daily gain.

Collaborative work from Penn State and the Nurture Research Center (Suarez-Mena et al.) showed that calf starter could contain up to 20% distillers grains with no negative effects on growth performance or rumen development in calves less than 2 months of age. For weaned calves up to 3 months of age, feeding 20 or 39% distillers grains in a grower feed reduced average daily gain and feed efficiency by 5 to 10%.

Monensin levels in starter were evaluated at the University of Minnesota (Chester-Jones et al.) Calves fed starter containing 0, 41, 47, or 70 mg/kg of monensin for the first 56 days of life had similar average daily gains (1.53 lbs/d). However, starter intake decreased as monensin level increased, improving feed efficiency by 3% in calves fed the highest level of monensin compared to those fed none. From 9 to 25 weeks of age, all calves were fed the same grower diet with 43 g/kg of monensin. However, average daily gain and hip height gain tended to be higher in calves fed increasing levels of monensin in the first 2 months of life.

Housing and Heat Stress
Three studies from the Nurture Research Center investigated calf facilities (Hill et al.). In one trial, daily gain of calves in wire mesh pens in a naturally ventilated nursery barn was 7% higher than that of calves in plastic hutches.

A second trial found that calves in nursery pens with straw bedding had greater daily gains and starter intake and fewer cases of scours than calves bedded with sand in the nursery or in hutches. Researchers proposed that improvements in calf performance were due at least in part to better ventilation in the nursery barn, which resulted in lower concentrations of airborne bacteria.

In the third trial, daytime (8 a.m. to 5 p.m.) cooling with fans during summer resulted in 23% greater weight gain, as well as better feed efficiency and greater hip width change and a reduced respiration rate compared to calves that were not cooled; all calves in this study were housed in a naturally ventilated nursery barn.

Texas A & M research also reported on the effects of heat stress (Chavez et al.). Calves were housed inside in a controlled environment where temperature ranged from 70 to 77°F and the temperature-humidity index remained below 80 or outside in a covered facility where temperature ranged from 77 to 99°F and the temperature-humidity index was above 80. Various feeding rates were also studied, but there were no differences due to feeding rate and those results will not be presented here.

Calves housed inside gained 10 lbs more over the course of the 42-day study and consumed 1.3 lbs more starter each day than calves housed outside. Calves housed outside drank 0.46 gallon more water per day than calves housed inside and had higher respiration rates. Rectal temperatures were higher in inside calves at 6 a.m. and higher in outside calves at 6 p.m. Although calves housed outside attempted to cool themselves by drinking more water and increasing their respiration rate, these adaptations were unable to compensate for heat stress.

Source: Coleen Jones, research associate, Department of Dairy and Animal Science, Penn State