Managing stress, feed and water for healthy weaned lambs discussed

by Whitt Stewart and Jedidiah Hewlett

Weaning is one of the most stressful periods in a lamb’s life, whether they are headed to the feedlot or staying on the ranch as replacements. Proper management during this time is essential for optimizing performance. 

The stress of weaning often leads to a decrease in feed intake and a weakened immune response, which can result in weight loss and increased susceptibility to disease. 

Understanding and effectively managing these challenges is crucial to ensuring lambs thrive post weaning.

Understanding stress and body weight loss during weaning 

Sheep producers know the weaning period is stressful for lambs, often detected by depressed immune response and a reduction in feed intake. 

Data from last year’s University of Wyoming Lamb-A-Year program, which involved 100 lambs from 20 different ranches, provides valuable insights into the challenges of the post-weaning period. 

During the two weeks following arrival at the feedlot, lambs initially weighed around 105 to 107 pounds. Lambs exhibited fairly consistent dry matter intake (DMI), consuming about 2.4 pounds of feed per day during this period, regardless of whether they received a respiratory vaccine.

Although there was no observable decrease in feed consumption, lamb weights declined. Those fed unchopped hay lost approximately 9.2 percent of their initial body weight, and lambs fed chopped hay lost about 2.8 percent. 

This highlights maintaining good feed intake during the stressful feeder lamb-receiving phase is a strong predictor of overall lamb performance, emphasizing the importance of providing palatable, easily-accessible feed to support post-weaning recovery and reduce initial shrink. 

Understanding these dynamics allows producers to implement strategies to minimize weight loss and enhance lamb performance during this critical period.

Is hay good enough for the stressful post-weaning stage? 

Encouraging lambs to settle into their new environment and consume feed consistently after weaning is crucial for reducing stress. 

Lambs typically consume 2.5 to three percent of their body weight in hay, but this intake can decrease if the diet consists of low-quality hay or increase with smaller particle size feed.

When feeding hay, it’s important to offer more than the standard daily amount so lambs can select the leafy, more digestible portions, rather than expecting them to clean up all of the hay, which can be unrealistic. 

A laboratory feed analysis is helpful in determining whether the hay is suitable for post-weaning needs.

Weaned lambs weighing between 60 to 90 pounds need approximately 0.2 to 0.33 pounds of crude protein and 1.5 to 2.25 pounds of total digestible nutrients (TDN) daily to support moderate growth. Their diet should contain 13 to 18 percent crude protein and 73 to 80 percent TDN.

For example, feeding a 70-pound lamb low-quality meadow hay might only partially meet its crude protein and TDN requirements, potentially leading to slower growth and reduced performance. 

In contrast, offering a higher-quality alfalfa-grass hay mix is more likely to meet or exceed these nutritional needs, providing better support for the lamb’s growth.

By understanding how different feeds measure up against these nutritional requirements, producers can make informed decisions to ensure the well-being and optimal growth of newly weaned lambs.

The overlooked impact of water quality on sheep health and performance 

Sometimes the greatest challenges in receiving feeder lambs are the most easily overlooked. A clean, visible water source which is easy to maintain is critical to a smooth transition. 

Lambs from range operations may require training if they are unfamiliar with drinking from a trough. 

It’s generally recommended to provide approximately one linear inch of trough space per lamb, although this can vary depending on location and environmental conditions. 

According to National Research Councilʼs  2007 recommendations, 60-pound lambs will consume approximately 0.8 to 1.2 gallons of water per day, while 90-pound lambs will need 1.2 to two gallons daily.

Ensuring water quality through regular cleaning is relatively straightforward, but addressing water quality issues specific to different ranching environments can be more challenging. 

Water quality issues, though challenging to manage, are crucial to preventing production losses. In 2015, Petersen et al. found a significant portion of livestock water sources, including surface water, groundwater and springs, exceeded recommended levels for iron at 66 percent, sodium at 42 percent, sulfates at 37 percent and pH at 36 percent over five years. 

Similarly, in 2018, Page et al. reported in 20 Montana sheep operations, 40 percent of water sources exceeded sodium standards, 35 percent had high sulfate levels, 20 percent had problematic pH and 10 percent were high in iron. 

Understanding these water quality challenges helps ranchers develop proactive strategies to prevent performance losses and mineral deficiencies.

Mineral and vitamin supplementation

A complete vitamin and mineral package is essential post weaning, as these nutrients are critical for immune function, digestion and skeletal and muscle growth. Keep in mind the late summer diet of lambs is likely deficient in many minerals and vitamins due to the declining quality of mature grasses. 

Calcium and phosphorous are two minerals requiring special attention in lamb diets. 

If calcium and phosphorous are not properly balanced, urinary calculi can occur. To avoid this complication, the calcium-to-phosphorus ratio should be between two to one and four to one. Providing a complete mineral supplement is vital. 

Ensure the mineral is specifically labeled for sheep and monitor consumption to avoid deficiencies or overconsumption. Depending on the type of supplement, target intake can vary – up to four ounces per head per day with a lick tub or about 0.75 ounces with granular mineral. 

To ensure adequate intake, make sure the mineral is fresh, not caked or weathered. 

Data from the 2023-24 UW Lamb-A-Year program showed lambs exceeded the target intake on 23 out of 24 days. The variation in mineral products on the market is significant and worth further exploration. 

Feel free to consult a member of the UW Sheep Task Force for additional guidance. 

Conclusion 

The post-weaning period is a critical time when lambs are vulnerable to stress and nutritional challenges. Proper management of feed, water and mineral supplementation is essential to minimize weight loss and support lamb health and growth. 

By providing high-quality, accessible feed, clean water and balanced minerals, producers can significantly enhance lamb performance during this transition. 

Remember, consulting experts and using data-driven strategies can further optimize the health and productivity of one’s flock.

Dr. Whit Stewart is an associate professor and the University of Wyoming Extension sheep specialist. He can be reached at whit.stewart@uwyo.edu or 307-766-5374. Jedidiah Hewlett is the University of Wyoming Extension agriculture and natural resources educator serving Converse County. He can be reached at jhewlett@uwyo.edu or 307-358-2417.