Jersey producers in areas of cold winters have expressed concern about poor growth and survival of young Jersey calves housed in hutches during the winter. Cold temperatures alter digestive processes and increase energy needs for maintaining body temperature, resulting in increased nutrient requirements of calves. Research data indicate that Jersey calves are less tolerant of cold environmental conditions than Holsteins. In addition, because Jersey calves are smaller, their larger ratio of surface area to body mass increases losses of heat by radiation. Consequently, factors improving the ability of Jersey calves to withstand cold temperatures are of interest.

Personal communications with Midwest Jersey producers and our experiences with the University of Illinois Jersey herd point to the difficulties of raising newborn Jersey calves in hutches when feeding milk replacers. Concern exists that the recommendations for mixing and feeding milk replacers are not adequate for Jerseys, especially those raised outside in winter. Recent reports indicate that the addition of energy as fat to milk replacers improved weight gains and efficiency of feed conversion by Holstein calves. Another strategy to increase energy intake would be to feed more milk replacer solids by making the milk replacer more concentrated.

The objectives of this study were:

1. to determine conditions necessary for survival and growth of Jersey calves housed in hutches during the winter, and
2. to determine if feeding additional fat or additional milk replacer solids would improve growth and health of Jersey calves.

MATERIALS AND METHODS

Jersey bull calves from the University of Illinois herd or purchased from cooperating dairy producers in Illinois were placed into hutches within 1 day after birth or upon their arrival at the farm. Calves were hand-fed colostrum immediately after birth and for the first day of life. Calves were fed whole Jersey milk at 10 percent of body weight for two days and then were switched to milk replacer. Milk replacers (22 percent crude protein, 20 percent fat) were fed twice daily for 28 days; during days 29 to 35, calves were fed half of the amount of milk replacer fed the preceding week (fed once daily), and calves were weaned on day 36. Calf starter was available at all times, and water buckets were thawed (if necessary) and filled twice daily. Starter intake was measured weekly through day 42. Calves were weighed and measured weekly, at which time body temperature was recorded and a blood sample was obtained. Fecal scores were assigned daily, on a scale of 1 to 5 (1 = normal, 5 = watery).

Milk replacer manufacturers recommend feeding milk replacer at 8 to 10 percent of body weight when reconstituted to 12.5 percent solids concentration. Preliminary experiments determined that a feeding level of 8 percent of body weight did not support gains of body weight; in fact, several calves lost body weight. Health of calves also was a problem, with frequent incidences of scouring. Feeding milk replacer at 10 percent of body weight maintained calf body weights, but calf health and vigor still were deemed unsatisfactory. Milk replacer reconstituted to 12.5 percent solids and fed at 12 percent of body weight supported weight gains and satisfactory calf health; therefore, these conditions were selected as the control diet for the remainder of the experiment.

Thirty Jersey calves were assigned to one of three treatments:

1. control: milk replacer (Nursing Formula; Land O'Lakes, Inc., Ft. Dodge, IA) reconstituted to 12.5 percent solids and fed at 12 percent of body weight, divided into two feedings daily;
2. control plus 75 grams per day of a fat supplement; and
3. milk replacer reconstituted to 15.5 percent solids and fed at 12 percent of body weight daily, divided into two feedings.

The fat supplement (Milk Specialties Co., Dundee, IL) consisted of choice white grease and whey protein concentrate, and contained 57.5% fat and 7% protein. Treatments 2 and 3 were designed to supply equal amounts of additional energy.

RESULTS

Addition of fat or extra solids to the milk replacer did not affect average daily gains of the calves (Table 1). Intake of starter was depressed for calves fed the additional milk replacer solids, and tended (P < .10) to be lower for calves fed fat (Table 1).

The average fecal score tended (P < .10) to be greater for calves fed fat during the first 14 days of the experiment (Table 2), but was not different among diets when averaged over the entire experiment (42 days). There were no differences among diets for body length, height, or heart girth (Table 2).

The concentration of glucose in blood plasma did not differ among diets (mean = 97.7 mg/dl). The concentration of nonesterified fatty acids in plasma was increased for calves fed fat (148, 184, and 148 µeq L for control, added fat, and additional milk replacer treatments, respectively), which is commonly observed when supplementing fat to diets of calves or cows. The concentration of urea in plasma was similar among treatments (mean = 8.5 mg/dl).

CONCLUSIONS

Health and growth of Jersey calves housed in hutches during the winter were satisfactory when the calves were fed milk replacer (reconstituted to 12.5 percent solids) at 12 percent of body weight. There was no advantage to adding a fat supplement to the milk replacer or to feeding additional milk replacer solids by reconstituting the milk replacer to 15.5 percent solids. Feeding the additional fat or solids tended to decrease intake of calf starter.

Table 1. Average daily gains (ADG) and starter intakes for Jersey calves housed in hutches during winter.

^a,bLeast squares means within a row without a common superscript are different (P<.05).

Table 2. Fecal scores and average changes in stature measurements for Jersey calves housed in hutches during winter.

^aFecal score tended (P<.10) to be greater for high fat than for control or high solids.