14th September 2018 | News
New research has shed light on the relevance of previously unknown masses in sieved cow manure.
One of the ways in which feed utilisation can be measured is through rumen audits. As well as assessing general cow health and housing standards, a rumen audit will examine a range of manure samples and assess for colour, content and consistency. Masses of undigested material known as ‘clay balls’ have for years been found in manure, with little known about their composition and causes.
New research undertaken at Myerscough College, in conjunction with Agri-Lloyd looked at what these masses are made from and how and when they are formed.
Analysis into the composition of these masses showed that on a dry matter basis, they contained little to no sugar, starch or oil. They did however contain high levels of protein, ash (inorganic material) and fibre. In fact, the masses were higher in crude protein and ash than the ration being fed to the cows, fresh manure and the other non-sievable manure material, as shown in figure 1.
Further analysis for mineral content showed the masses were statistically higher than the forage for phosphorus, calcium, magnesium, zinc, cobalt, selenium, manganese and copper. Potassium and sodium were statistically lower with sulphur, molybdenum, iron and aluminium showing no statistically significant difference indicating that these masses were not a result of soil ingestion.
A full trial was carried out at Myerscough College’s Lodge Farm involving 77 cows over a 10-week period to further examine the correlation between the presence of the masses and herd health.
The cows were split into three groups at the start of the study. Group one was milking cows with normal milk quality; group two was milking cows flagged for weight loss or changing milk quality; group three were dry cows due to calve mid-trial.
Manure from the three groups was checked for undigested masses three times a week and also measured for indicators of digestional upset, such as mucin casts in the manure which would indicate sub-acute ruminal acidosis was occurring.
At the start of the trial, group one had a lower level of undigested masses than group two.
In group two, cows with potential digestive upsets had the largest amount of masses. Other cofactors such as ketosis and mastitis were similar to group one indicating that these masses were a result of impaired digestion.
By the end of the study however, the levels of undigested masses in group 1 rose to the same level as those in group 2 despite none of the cows showing signs of digestive upset.
Interestingly, none of the dry cows had any masses in the manure pre-calving; however, immediately after calving, the prevalence increased to the level seen in the two other groups.
Figure 2 – Observations on a dry cow
The ration being fed to the cows was also monitored over the study to identify any correlation with the increase in the masses.
The rations increased over time in protein, metabolic energy (ME) and mineral content which coincides with the increase of undigested masses in the ‘normal’ group at the end of the study.
The dry cow ration had the lowest level of protein and minerals however, once the cow had calved they moved onto the milking cow ration and subsequently there was a presence of the masses.
Anya Westland, Senior Lecturer and Researcher at Myerscough College says: "This research demonstrates the potential link between the presence of these masses and protein and mineral absorption.
Their presence could indicate the cows are suffering from a digestive upset causing impaired protein/mineral absorption or alternatively that protein/minerals are being fed in excess. Both of these would indicate there is a need to reassess the ration to ensure these components are being effectively utilised by the cows in order to maximise performance whilst not wasting feed."
Sally-Ann Emmas, Head of Research and Development for Agri-Lloyd, says: "As protein and minerals are often provided in excess in cattle rations, it is expected these components will not be fully absorbed and utilised by the herd. However, this is exacerbated when there are underlying impairments to digestive health."
Dr Emmas adds it is important farmers properly utilise rumen audit services to understand the health of the rumen function and optimise their ration to improve production and identify health problems such as sub-acute ruminal acidosis.