Profitable dairy herds are built on a foundation of continuous improvement in efficiency and output. Cows which produce more milk per kilogram of feed consumed will inevitably be more profitable than less efficient animals. Similarly, herds which have a lower replacement rate are more profitable than herds with a higher replacement rate because rearing replacement animals is costly, plus first and second lactation animals produce 15 and 25% less milk than older cows in their third or subsequent lactation animals.
Careful selection of genetics is a tool to help improve efficiency. Another important consideration is heifer management from birth through to first calving - which can affect the lifetime productivity of an animal and affect profitability of the herd.
Data from New Zealand herds has shown that, regardless of the breed of heifer, there is a strong positive relationship between body weight throughout rearing and first lactation milk production (Handcock et al., 2019)[i], while heifers which are heavier at 12 months of age have greater cumulative milk production through to their third lactation (Handcock et al., 2020)[ii].
What is particularly interesting though is the magnitude of the effect that good feeding and management in the first eight weeks of life can have on the lifetime productivity of a dairy heifer.
In a long-term trial carried out by Trouw Nutreco[iii] between 2014 and 2020, 86 heifers were fed either 4L or 8L of milk replacer from 2 days of age through to 42 days of age and weaned by 56 days of age (figure 1). Both groups of calves were offered ad libitum access to fresh water, calf starter and wheat straw.
From 56 days of age, calves were all fed the same. As expected, those calves allocated a greater volume of milk grew faster and achieved a higher bodyweight by weaning age (figure 2).
In addition to early growth rates, the survival of heifers and production in their first and second lactation was also measured (Figure 3).
By first calving, 93% of heifers fed 8L of milk remained in the herd compared to only 88% of those heifers fed 4L of milk, while by the start of their 3rd lactation only 37% of heifers fed 4L of milk survived compared to 53% of heifers fed 8L of milk.
Surviving heifers fed 8L of milk were also more efficient converters of feed into milk, producing more milk fat than surviving heifers fed 4L of milk, an effect which carried through into the second lactation.
In the trial carried out by Trouw Nutreco, calves were fed either 4 or 8L of milk replacer for the first 56 days of life, but there are many other ways in which growth rate and development in early life can be positively impacted.
1. Colostrum first
Ensuring adequate colostrum intake within the first 12 hours of birth not only helps to ensure that the young calf receives adequate immunoglobulins to help protect them against disease but also provides essential growth factors which help drive early gut development and growth. Implementing a colostrum management plan to ensure that colostrum is high quality (>22% brix), is clean and free of contamination, and that calves are fed at least 5% of their body weight within 12 hours of birth and again within 24 hours, may seem complicated, but the returns are worth it. International research[iv] shows a strong correlation between blood IgG levels and heifer growth and efficiency of feed utilisation.
2. Ensure high nutrient intakes
Although researchers in the trial described above reported the effect of increasing the volume of milk fed on the performance of heifers, they were in fact comparing the effect of increasing the availability of nutrients to the calves – an effect which can also be achieved by feeding a more digestible milk or milk replacer.
Practical experience of farmers in New Zealand has shown the benefits of feeding a highly digestible milk replacer, providing more digestible nutrients per kilogram, on the effect of calf growth rates (figure 4).
Under New Zealand conditions, and particularly with the labour shortages currently being experienced on farm, once a day feeding systems are commonplace. Inevitably these systems limit the volume of milk which can be fed to a calf and consequently nutrient intake and early growth rates are restricted. Fortifying whole milk or using milk replacer at an increased mixing rate in these systems allows greater intake of nutrients, faster early growth and ultimately better lifetime productivity.
3. Minimise growth checks at weaning
Although pre-weaning growth rates have the potential to dramatically influence lifetime productivity, growth checks post weaning undo some of the good work done in early life. So, it is important when considering calf to nutrition to consider both pre and post-weaning nutrition and how to optimise both without compromising one or the other.
Ensuring clean, fresh, palatable hard feed is freely available for calves from day old helps to encourage early feed intake and helps to support early rumen development, easing the transition from milk to hard feeds and pasture. The high starch content of a good quality calf meal or pellet is vital for the development of rumen papillae, essential for the efficient absorption of volatile fatty acids produced through bacterial fermentation of pasture and hard feeds in the rumen.
Feeding a high quality, highly digestible, whey-based milk replacer as part of your milk feeding programme, either as the primary milk source, as a follow-on feed after transition milk and prior to weaning, or as part of a fortified milk feeding programme can help to encourage early intake of hard feed while still supporting rapid early growth and development.
4. Minimise disease
It is also important to recognise that disease challenges, either because of high pathogen load in a shed or surrounding environment, poor air quality, and cold stress increase the proportion of nutrients which the animal uses for maintenance, leaving less for growth.
Good shed design to ensure adequate air-flow and the absence of draught and thorough cleaning and disinfection of the shed prior to the arrival of calves are all important in helping to support optimal growth rates.
Also, ensure the pH of the animal environment is not too alkaline. Work carried out in the Waikato in the early 90’s showed fresh bedding to have a pH under 7. Once used, the pH of bedding increased – with areas where there was a higher concentration of urine and faeces increasing to above 8 in most cases. A highly alkaline environment not only harbours bacteria but also breaks down the animals’ skin sebum, making them more prone to infection. So, it is important to use a powerful (preferably acidic) drying agent that absorbs moisture and neutralises ammonia – adjusting the pH of litter from alkaline to neutral – to create a healthy rearing environment.
Article supplied by AgriVantage.
[i] Handcock, R. C., Lopez-Villalobos, N., McNaughton, L. R., Back, P. J., Edwards, G. R. and Hickson, R. E., 2019. Positive relationship between body weight of dairy heifers and their first-lactation and accumulated three-parity lactation production. Journal of Dairy Science, 2019, 102, 4577 - 4589.
[ii] Handcock, R. C., Lopez-Villalobos, N., McNaughton, L. R., Back, P. J., Edwards, G. R. and Hickson, R. E., 2020. Increased yearling weight as a proportion of 21 month weight was associated with increased milk production in dairy heifers. New Zealand Veterinary Journal, 2020, 68, 272 - 282.
[iii]https://reader.elsevier.com/reader/sd/pii/S0022030221005439?token=D0FF2D8E87ED5DE3A0BFAE05B6C62CEDA44452FD59AC4E7605CC562CBDE2CAED8407A780962E02FDC68FBE2CB3E4167C&originRegion=us-east-1&originCreation=20221213222901
[iv] National Animal Health Monitoring System, 1994. Dairy heifer Morbidity, Mortality and Health Management, Focusing on Preweaned Heifers. USDA, Centre for Epidemiology and Animal Health, Fort Collings, Colorado.