24 Nov Autumn calving – a farm system study
Our farm system study comparing an autumn and spring calving system was recently published in the Journal of New Zealand Grasslands!
In this blog post we will share the main results from the study.
Background
There has been an increasing interest in autumn calving systems on the North Island of New Zealand in the recent years due to increasingly dry summers and an increase in the winter milk premium from Fonterra in 2017. In Taranaki, dry summers are also becoming increasingly challenging and in some areas autumn calving offers an advantage over spring calving. This is because, in an autumn calving system, cows are typically dry during the summer months, reducing the impact of seasonal feed shortages.
How?
The farm system study was performed on our DTT Kavanagh farm located on the coast in south Taranaki. The trial was run as a two farmlet trial with one autumn (104.0 ha, 301 cows, SR=2.9 cows/ha) and one spring (104.8 ha, 301 cows, SR=2.9 cows/ha) calving farmlet, over three full seasons (Season 1: 2019/2020, Season 2: 2020/2021, Season 3: 2021/2022).
What did we learn?
The first season of the trial had a dry summer and autumn compared to the two following seasons of the trial. In season 1 there was only 292 mm rain from January to May, while in the two next seasons rainfall was higher over summer and autumn (Season 2: 482 mm, Season 3: 679 mm).
The autumn farmlet had a higher demand for supplements than the spring farmlet (Season 1: 30%, Season 2: 68%, Season 3: 37%). The supplements fed over the three seasons are summarized in the figure below. Both farmlets fed the highest amount of supplements in the first season due to the dry conditions. The difference between the two farmlets was highest in the second season due to a substantial amount of PKE-based meal being fed to the autumn herd during peak lactation over winter, a carry-over effect of the dry conditions at the end of the previous season.
In the table below the milk production for the two herds over the three seasons is summarised. The autumn herd produced more milk solids per cow and per ha and had more days in milk than the spring herd in all three seasons. The difference between the two herds was largest in the first season due to the dry conditions in summer and autumn. The spring herd was milked once a day from February and dried off early in Season 1, while the autumn herd was less affected because its dry period occurred over summer. The higher milk production in the autumn herd throughout the study was not only a result of more days in milk but also its flatter lactation curve, which sustained higher milk yields for a longer period compared to the spring-calving herd.
In terms of animal health there was no clear trends in treated cases of lameness and mastitis between the two herds. The autumn herd had higher average body condition scores at calving, mating and dry-off. The difference was largest at dry-off due to the high pasture growth and pasture quality in spring coinciding with the end of the lactation period for the autumn calving herd. This enabled more days in milk for the autumn herd while still achieving target body condition scores at calving.
In an autumn calving system mating usually starts in June. Mating during winter is often considered challenging due to harsher weather conditions and less daylight hours. However, in our study we only observed slightly higher empty rates for the autumn herd (2 – 4 % above the spring herd).
A financial analysis showed that the autumn farmlet had higher gross farm revenue all three seasons (see table below). This was mainly due to higher milk production and the winter milk premium. The autumn farmlet also had higher operating expenses mainly due to the higher amounts of supplements fed. Despite having higher operating expenses, the autumn farmlet had a higher operating profit all three seasons. On average over the three seasons, the autumn farmlet had a 33% higher operating profit. Even without the winter milk premium, the autumn system would have remained more profitable in the first two seasons and only slightly less profitable in the third. If the winter milk premium were reduced by 50%, the autumn farmlet would still be more profitable in all three seasons. The difference between the two farmlets was again highest in the first season of the trial driven by the dry summer and autumn conditions.
Opportunities of an autumn calving system
We found in our study that it is possible to achieve increased milk production and profitability in an autumn calving system, especially if the summers are dry. The autumn herd had a higher average body condition score at the end of the season enabling more days in milk contributing to the higher milk production. In an autumn calving system, the cows are calving in March in a more favourable climate compared to spring calving. An added benefit for the farmer is that the cows are dry over summer, making it easier for the farmer to get off farm during summer.
Challenges and risks of an autumn calving system
The profitability of the autumn calving system is sensitive to the winter milk premium and the cost of supplements. Farmers need to be prepared to feed more supplements during winter and have the suitable infrastructure. In the current study the PKE-based meal was fed through an in-shed feeding system. If it had been offered on a feed pad or in paddocks, labour costs and feed waste would have increased for the autumn farmlet. Maize, however, was fed in the paddock, resulting in high wastage in this study. This could be reduced when feeding it on a feed pad. Milking through winter can present challenges in regard to climate and pasture management. Mating during winter can be difficult as well, although we did not see large differences between the herds in our study. The environmental impact of the farm system should also be considered, given that the autumn system required larger amounts of supplement. Factors such as management practices, other inputs like fertiliser and the increase in per cow production while keeping the same stocking rate will all influence the carbon footprint of the milk produced, this needs to be calculated for each farm system individually.
For more details on our autumn calving study have a look at the full article in the link below:
