Farm Table says:
What is the problem?
Weed seeds can remain viable after digestion in ruminants, and researchers from the University of Tehran and the University of Melbourne investigated if different cattle groups, particularly in dairy, had different rates of seed viability after digestion. Dairy manure is often used as compost, and may contribute to the spread of weeds on farm.
What did the research involve?
The researchers used 4 weed species, Cuscuta campestris, Polygonum aviculare, Rumex crispus and Sorghum halepense, collected in Iran in 2009. Four cows in four different groups were used, and fed a total of 120000, 60000, 60000, and 72000 seeds for lactating cows, dry cows, growing heifers, and feedlot male calves, respectively. Seed numbers were calculated based on feed requirements. Details of the 4 groups of cows used are as follows;
1- lactating cows (weight 600±50 kg, 24–28 months old, 50 days in milk)
2- feedlot male calves (weight 410±30 kg, 10–12 months old)
3- dry cows (weight 650 ±50 kg, 35–38 months old)
4- growing heifers (weight 400±25 kg; 12–15 months old)
Dung was collected daily and sieved, with weed seeds collected and tested for viability.
What were the key findings?
The most seeds were recovered two days after seed intake in all cattle groups. Taking all weed species into account, dry cows had the lowest seed recovery of 36.4%, and lactating cows the highest at 74.4%. A significant difference was seen between cattle groups when it came to seed recovery and viability.
The researchers suggest that in a weed management plan involving livestock, the group type should be taken into account to minimise weed spread through passing of viable seeds.