New research from Cornell University might provide you with some insight for next year’s lambing season. A study done by Ann DiPastina in conjunction with Dr. Debbie Cherney may help producers decide if milk replacer or ewe’s milk is the best decision.
The study tackled two questions. Does the composition of ewe’s milk change through lactation? And, are the growth rates different between lambs on milk replacer compared to those on ewe’s milk?
For the study, twin lambs were separated into two groups: lambs fed milk replacer and lambs left with the ewes to be raised naturally. Artificially reared lambs were housed in 0.9 x 0.9 meter pens in pairs and offered free-choice access to Land O’Lakes Ultra Fresh® Optimum lamb milk replacer. Naturally reared lambs were housed with their dams in 1.5 x 1.5 meter pens with access to a 0.6 x 1.5 meter creep area.
The first phase of the research focused on the ewes and their milk production. The objective was to measure potential changes in milk composition.
The research first focused on milk composition from the ewes. They collected milk samples from each ewe six time a day on days 18, 19, 20, 38, 39, and 40. The samples were checked for fat, protein and lactose. Although the averages over time were similar to milk replacer the protein and lactose levels were higher later in lactation than in the earlier sample.
The researchers also noted differences in milk composition based on the time of day, with highest production being at 4:00-8:00 a.m. DiPastina suggests that these factors provide inconsistent nutrition to the growing lamb.
Knowing the nutritional inconsistencies, the researchers looked to growth rates. Lambs were weighted each day at 8:00am until 30 days. Creep feed and milk replacer intake were measured three times a day. The results lined up with the nutrition from the ewes, with higher average growth rates for lambs receiving milk replacer– .66 lb/day compared to .62 lb/day.
“The artificially-reared lambs were smaller, on average, than naturally-reared lambs at birth but tended to reach the same final weight at day 30,” says DiPastina.
Creep feed consumption between the two groups was nearly uniform; thus, the researchers point to consistency in nutrition as a driver in the increased growth rates.
“A potential reason for the elevated growth rates in artificially-reared lambs could be the consistency of energy intake,” says DiPastina. “Results indicated that milk yield varies significantly throughout the day. Lambs’ intake levels may have therefore fluctuated throughout the day as well.”