Except in New Zealand and parts of Australia and Chile, almost all herds produce milk on a year round basis, with some cows calving during each month of the year. This ensures a relatively uniform supply of milk to the processing companies. By contrast, the majority (95%) of dairy farms in New Zealand supply milk on a seasonal basis, and calving is timed to coincide with the commencement of increased pasture growth during the spring. This concentrated pattern of calving (most NZ dairymen aim to calve 80% of the herd within 4 weeks, and 100% of the herd by 8 weeks) produce a very uneven pattern of milk flow to the processing factories. The processing capacity of the factories is under-utilised for a significant part of the year and this influences manufacturing costs. On the other hand, on-farm milk production costs are low because maximum advantage is taken of low-cost pasture.
Seasonal milk production offers dairymen a number of other benefits, and it is something which small- to medium-sized herds should give some thought to.
Seasonal dairy production simply means the production of milk for part of the year (usually 10 months). Normally the ‘seasonality’ of production corresponds to the seasonal pattern of herbage production, and involves the matching of herd feed requirements to the rate of herbage growth. Peak cow feed requirements usually occur 6-8 weeks after calving, and in the absence of non-pasture feeds, can be most easily met if the cows calve so that maximum intakes occur at the same time as maximum herbage growth. For example, in New Zealand the highest rates of herbage production occur from late September-November and most herds calve during late July and August. The situation in your district may not be as straight forward because insufficient energy can be obtained from a pasture-only diet to maintain the higher levels of milk production you are seeking to achieve (70lbs+ cow/day vs 35-45lb/cow/day in New Zealand).
Two alternative seasonal dairying systems are available to Northern Hemisphere dairymen:
1. Late winter-early spring calving
Cows are calved in March and April. This system attempts to make maximum use of pastures, and is probably best-suited to lower producing herds with a low-cost feeding system.
2. Fall calving
Under this system cows calve in September and October and the first half of lactation during the cold winter period is completed indoors. Cows spend the second half of the lactation grazing pasture and are dried-off in early July. This system allows high per cow milk production to be maintained in the first 24 weeks of lactation, and requires a lower level of supplementation while cows are on pasture, during weeks 25-44 of lactation. In addition cows are not being milked during the hottest summer months and dry cows are able to be kept outdoors on a mainly pasture diet during this time. The fall calving option will allow traditional fall milk premiums to be captured and provide a flexible turn-out date for grazing during spring.
The advantages of seasonal milk production include:
a. Improved farmer lifestyle. The 4-6 weeks when cows are not milking provides time for a holiday. This time can also be used to catch up on farm repairs and maintenance.
b Simplified livestock management. A concentrated calving means that herd replacements can be reared in a single group, and that the herd is all at a similar stage of lactation. This simplifies feeding management and has the potential to provide cost-savings through more efficient use of feed (i.e. avoidance of cows not being over- or under-fed).
c. Reduced production costs, through the use of grazing, especially if minimal grain feeding is adopted during the second half of lactation.
d. Improved herd reproductive performance because cows are mated at the ‘natural’ time of cycling. A reduced calving interval and a higher calving rate both contribute to improved profit.
The main disadvantages of seasonal dairying are:
a. A reduced lactation length. The average lactation in New Zealand seasonal supply herds is 237 days. This compares with a typical value of 305 days for year-round calving herds. The shorter lactation in New Zealand primarily relates to an abrupt drying-off date. A staggered drying-off period, which can easily be implemented elsewhere through the use of mixed rations would increase the average number of days in milk for the herd.
b. Lower average milk yields may occur especially with the spring calving option. The seasonal dairying system may be better suited to Jersey cows than Holsteins.
c. The transition to seasonal dairying take several years to complete because calving dates cannot be quickly shifted into a concentrated pattern.
d. Decreased industry plant efficiency as discussed earlier, but this is not likely to be significant because seasonal dairying is probably inappropriate for large dairy herds or for farms with a small area of pasture. In addition, a balance of spring and fall calving herds should even out the monthly supply of milk.
The economics of seasonal dairying are likely to have been evaluated for your region and you should refer to these reports to get an idea of how seasonal dairying might work out on your farm. Before you decide to switch to seasonal dairying you will need to look at the specifics for your farm. As indicated above this evaluation should include both economic and non-economic factors.