This year’s British Society of Animal Science conference looked at everything from whether organic or conventional dairy production was better for the environment to the best concentrate allocation for dairy cows. Sarah Trickett gives a brief insight in to the latest findings
Organic production – goood or bad?
Organic production may have declined in recent years, but it is still seen by some consumers as a system that produces safe and healthy food with consideration for the welfare of the animal and the environment.
However, do organic systems really meet the need for the environment and animal welfare? According to new research, that answer could be no.
Researchers at Massey University, New Zealand, found organic dairy cows that were rotationally grazed in organic paddocks emitted significantly higher carbon emissions than conventionally grazed cows. More organic cows were also culled due to mastitis.
The reason for the higher carbon emission was the fact organic cows had lower milk yields and stocking rates, along with increased levels of land required for rearing replacement livestock. A higher level of replacements was mainly due to culling of relatively young organic cows due to Strep uberis mastitis, especially in early lactation. Conventionally managed stock also had higher milk yields and stocking rates.
Wildflowers help reduce emissions
Feeding a ryegrass/wildflower forage mix could help reduce carbon emissions, according to research by the University of Reading.
The trial compared feeding baled haylage of perennial ryegrass, ryegrass and red clover, ryegrass and birdsfoot trefoil and ryegrass and wildflowers.
Results found growing dairy heifers fed the ryegrass/wildflower mix emitted less methane a day compared to the other mixes.
It is believed this is because the production of methane by ruminants is influenced by the type of carbohydrate available for fermentation. The concentrations of plant secondary compounds may have contributed to wildflowers’ effects on methane emissions and may also have affected the digestibility and fermentation of forage in the rumen.
Increase in concentrate feeding
The amount of concentrates fed to dairy cows has more than doubled in the past 15 years from 1.1t a cow a year to 2.4t in 2012, with milk produced from forage reducing from 3,200 litres a cow to just 2,150 litres.
However, with feed prices continuing to rise and mixer wagons and out-of-parlour feeders regularly replacing in-parlour feeders, is the way concentrates are allocated to dairy cows correct?
Ryan Law at the AgriFood and Biosciences Institute, Northern Ireland, compared four methods of feeding concentrates:
1. A complete diet fed at a flat rate
2. Out-of-parlour feeders fed at a flat rate
3. Feeding to yield – whereby cows were allocated to one of three concentrate curves based on milk production in week two and three
4. A basal diet and field to yield – whereby all cows were offered a basal ration containing 6kg concentrate a cow a day as well as being allocated to one of three curves based on milk production in week two and three of lactation.
Dr Law found there was no effect on production by feeding concentrates via the different methods. He concluded that when allocating concentrates to meet the expected nutrient requirements of the average cow in a group of cows with a tight calving pattern, concentrate allocation strategy will have little effect on overall performance.
Future breeding tools for Johne’s resistance
Breeding tools could be developed in the future to help breed cattle that have a low level of resistance to Johne’s disease.
Research by Scotland’s Rural University College looking at the genetic analyses of Johne’s testing data found that despite the low heritability of health and fertility traits, genetic progress can still be made.
For example, there was a genetic turnaround in the genetic trend of fertility almost immediately after the fertility index was introduced which includes traits with heritability’s of 1-4%. Since testing of Johne’s already take place such as the service offered by the National Milk Records (NMR) , the same field data could be used to develop breeding tools as part of an overall disease control strategy.
Move to indoor dairying
UK dairy farms are moving to more indoor feeding and continuous housing systems and away from traditional all-summer grazing.
According to a survey conducted by Scotland’s Rural University College of 828 farmers – representing six percent of dairy production holdings in the UK – traditional all-summer grazing is not the predominant system on UK dairy farms.
More than two-thirds of farmers involved in the survey said they had adopted some form of indoor summer feeding system, with only 30% of respondents farming in a traditional manner, grazing their cows in better weather.
More than 40% of farmers answering the survey also indicated they were feeding all their cows inside during the summer for part of the day, with 7% housing and feeding cows indoor year-round.
The survey also showed that as herd size increased, farmers tended to move away from a more traditional grazing system towards continuously housing their cows. This could indicate that increased herd sizes in low-input systems are not as profitable as more intensive systems that begin to become more economical at larger scales.
Boosting energy and fertility
Levels of protein and energy in a cow’s diet can significantly affected the ability of a cow to get in calf.
According to trial results from Scotland’s Rural University College, cows fed rations with relatively lower crude protein (180g/kg DM) and metabolisable energy (11.5 MJ) had a lower chance of pregnancy in the first three inseminations compared to those receiving diets with higher protein levels of 185g/kg DM and an ME of 12.3 MJ.
Genetic merit, days to first heat and body condition also influence the cow’s chance of getting in calf.
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