The first two months of a calf’s life can be challenging due to high risk of scours and respiratory disease – but this time is also one of opportunity because calves have the potential to grow very efficiently. While getting calves off to a good start is labor-intensive and can be frustrating at times, recent research has shown that keeping calves healthy and growing not only benefits the calf in the short term but can have long-term impacts on the productivity (and ultimately profitability) of the animal once it reaches the lactating herd.
Several factors affect calf growth, including genetics, immune function (e.g., colostrum, vaccinations), the environment (e.g., thermal stressors, pathogen load, air quality, grouping strategies) and the nutrition program fed (e.g., liquid feed, calf starter).
The objective of this article is to summarize recent findings with regard to the relationship between preweaning growth rates and lactation performance and discuss major areas of opportunity for optimizing preweaning growth and health.
Research from Cornell University found that growth rate as a calf positively influences lactation performance as a cow. In this study, calves were raised on an intensified plane of nutrition (28 percent CP milk replacer, powder fed at greater than 2 lbs per calf per day) from birth to weaning.
A comprehensive statistical analysis was conducted to determine whether preweaning parameters were significantly related to lactation in first lactation and beyond. For the 1,244 heifers completing first lactation, preweaning average daily gain (ADG) had a highly significant impact on first-lactation milk yield – every 1 lb of preweaning ADG resulted in 850 lbs of first-lactation milk yield.
This means that a calf that gains 2 lbs per day would produce 850 lbs more milk in first lactation than a calf that gained 1 lb per day. Additionally, the response for the 826 animals with complete second-lactation records had a similar milk response (+888 lbs of milk for every lb of ADG), indicating that the response lasts beyond first lactation.
Calves that have been sick (e.g., scours or respiratory disease) are typically more likely to lag behind their healthy counterparts in terms of growth. The Cornell study found that calves that had scours in addition to receiving antibiotic treatment (assumed to be for respiratory disease symptoms) had lower ADG than healthy calves, whereas calves with either scours or antibiotic treatment alone grew at similar rates as healthy calves.
Calves treated with antibiotics produced 623 lbs more milk per lb of ADG, whereas untreated calves produced 1,407 lbs more milk per lb of ADG, indicating that preweaning health issues blunted the calf’s first-lactation milk response.
This research further emphasizes the importance of preweaning management and nutrition due to their influence on long-term productivity. Colostrum management, nutrition and the weaning transition period are three areas where great strides can be made toward improving preweaning growth and health.
Colostrum is undoubtedly a critical factor influencing calf health. Calves are born relatively devoid of a functional immune system and must be provided with passive immunity through colostrum; therefore, much attention with regard to colostrum has been paid to delivery of adequate amounts of immunoglobulins (Ig) in a timely fashion.
Colostrum has been shown to influence calf growth independent of effects on health. Cornell University researchers conducted a study where calves were fed either 2 or 4 liters (2.11 to 4.22 quarts) of colostrum within the first hour of birth.
Half of each colostrum group was then assigned to either a conventional (4 liters per calf per day of milk replacer solution) or a high plane of nutrition (allowed up to 12 liters per calf per day of milk replacer solution). Colostrum intake did not affect calf growth among calves fed a conventional plane of nutrition. However, within the high-plane-of-nutrition group, calves fed 4 liters of colostrum had significantly greater ADG (1.72 vs. 1.21 lbs per calf per day) and post-weaning dry matter intake (6.17 vs. 4.85 lbs per calf per day) than those fed 2 liters of colostrum.
Feed efficiency was improved in calves fed 4 liters of colostrum regardless of plane of nutrition. These results suggest that colostrum management is a critical component enabling the calf to respond to an intensified plane of nutrition. Key colostrum management guidelines are:
1. Quality – Ig concentration in grams per liter
• Benchmark: Minimum concentration of 50 g per L
2. Quantity – Amount fed
• Benchmark: 10 percent of birthweight
3. Quickness – Of colostrum harvest and feeding
• Benchmark : Harvest and feed as soon as possible, preferably within four hours after calving
4. Cleanliness – Contaminated colostrum may be a source of disease (E. coli, Salmonella spp., Mycoplasma bovis) and may interfere with Ig absorption
• Benchmark: Less than 100,000 CFU per mL total bacteria count, less than 10,000 CFU per mL coliform count
The current industry benchmark for calf growth is to double birthweight by 60 days old. The nutrition program necessary to meet this goal likely differs from farm to farm or even month to month within farms depending on environmental conditions and calf health. Key areas to evaluate with regard to calf nutrition are:
• Liquid feed source – Saleable whole milk, pasteurized hospital milk or milk replacer. Each source comes with unique economic, biosecurity and feeding considerations. Evaluate crude protein and fat concentrations to ensure proper comparison among liquid feed sources.
• Solids feeding rate – Conventional milk replacer programs typically deliver between 1 and 1.5 lbs of powder per calf per day, while feeding 1 gallon of 12.5 percent solids whole milk would result in 1.1 lbs of solids intake.Intensified milk replacer programs are designed to feed milk replacer powder at 2 lbs per calf per day minimum – but be certain to select a higher-protein milk replacer (at least 24 percent) to promote frame growth rather than fat accretion at these higher feeding rates.
• Protein source – Milk and plasma proteins are considered ideal sources for calves, although it is important to note that protein quality can vary among ingredient suppliers. Modified soy protein and wheat gluten are also acceptable protein sources but will typically support lower ADG versus milk or plasma proteins, particularly in calves less than 3 weeks old.
• Calf starter – Intake/palatability is critical for calf starter. Be certain calves have ad libitum access, avoid excessive fines and maintain freshness in order to maximize intake.
The weaning transition period refers to the time during which calves are weaned from milk, relying solely on dry feeds and/or introduced to group housing.
If not managed properly, the weaning transition period can result in growth slumps due to inadequate grain intake, coccidiosis problems or increased incidence of respiratory disease, all of which can erase any performance improvements accomplished in the preweaning period. Some critical considerations for this challenging period include:
• Move to once-daily milk feeding for one week when calves are consuming at least 1.5 lbs per day of calf starter. Keep calves in preweaned housing for at least one week after full milk removal. Be certain calves are consuming at least 5 to 6 lbs of calf grain daily prior to moving to a new pen.
• If moving from individual to group housing, be certain to wean calves in groups and keep group sizes small (e.g., 10 calves).
• Avoid headlocks in the transition pen and always place feed and water on the fenceline to take advantage of the calf’s natural behavior to roam the perimeter of a pen.
• Do not offer hay until one to two weeks after grouping to allow for grain intake to rebound. Offering hay too early may lead to inadequate intake of coccidiosis medication, thus increasing the risk of subclinical or clinical disease.
• Evaluate air quality of both the preweaning and postweaning facilities. Airborne bacteria counts and nose-to-nose contact have been identified as contributors to respiratory disease incidence. Positive-pressure tube systems have been used with great success to deliver a constant supply of fresh air to the calf level in both individual and group housing facilities, provided they are specified and installed correctly for best (and not detrimental) results.
• Work with your veterinarian to ensure you have a comprehensive coccidiosis and respiratory control program. PD
References omitted due to space but are available upon request. Click here to email an editor.
David B. Carlson
Senior Technical Consultant
Elanco Animal Health