Aggressive milk-replacer feeding programs have demonstrated superior weight gain and structural growth for preweaned calves. But some producers and researchers also have observed that calves fed high levels of nutrients in the preweaned period struggle with the transition to dry feedstuffs post-weaning.

Researchers at the University of New Hampshire and the Nutrition and Research Center at Provimi North America, conducted a trial to assess how calves fed varied levels of milk replacer fared in terms of growth, health, digestive ability and transition-to-weaning success.

The study, published in the April 2016 issue of the Journal of Dairy Science, and summarized by Colleen Chapman, PhD candidate the University of New Hampshire, evaluated 96 male Holstein calves, starting at 3 days of age with initial bodyweights of 90.2 + 4.18 pounds. Feeding groups were separated into three milk-replacer rations:

(1)   1 lb. as-fed of 20% crude protein, 20% fat (20:20) milk-replacer powder per day for 42 days.

(2)   1.5 lb. as-fed of 26:17 milk-replacer powder fed for 42 days; and

(3)   2.0 lb. as-fed of 26:17 milk-replacer powder fed for 49 days.

Milk replacer feedings were reduced by half, delivered in a single feeding, for the last 3 days in groups (1) and (2), and the last 7 days for group (3).

All calves were fed an 18% crude protein, as-fed, texturized starter and water free choice for 56 days. Fecal samples taken during days 51 to 56 were collected and analyzed from five random animals in each group to estimate digestibility.

The study’s results included:

Feeding group

ADG, lb.

Feed efficiency, gain/feed

Change in hip width, inches

Digestibility of organic matter, %

Neutral detergent fiber, %

(1)

  0.77

35%

1.30

79

54

(2)

1.12

49%

1.61

78

51

(3)

1.21

48%

1.61

68

26

Group (3) also had the greatest change in body condition score, and consumed the least starter grain, of the three feeding groups. There was no difference in fecal scores or medical treatments among any of the groups. Frame growth (change in hip width) did not differ between groups 2 and 3, despite more milk replacer being fed to group 3.

Dry-matter intake per pound of bodyweight was lowest for group (1). Efficiency of average daily gain per unit of metabolizable energy intake also was lowest for group (1). Intake of dry matter per pound of bodyweight did not vary significantly between groups.

Despite similar or higher dry matter, crude protein and metabolizable energy intakes for group (3) over the full, 56-day trial, digestion declined significantly for group (3) in the week post-weaning. This resulted in some of the bodyweight gained in the milk-feeding period being lost for group (3) immediately after weaning. Starter intake for calves in group (3) substantially increased in week 7 when milk replacer was reduced, and in week 8 when milk replacer was removed. Digestion of sugar, crude protein and fat was lowest for group (3).

The authors concluded that feeding moderate amounts of milk replacer, similar to the program in group (2), would promote rumen development and digestion, and provide adequate nutrients for growth beyond maintenance, without causing the post-weaning slump experienced by group (3). When more aggressive levels of milk replacer are fed, as in group (3), they suggested longer periods of gradual weaning from milk replacer (such as 3 weeks versus the 1 week that was allowed in this study), to overcome poor post-weaning digestive performance.