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TMR audit roadshow highlights importance of variation

Inconsistency in rations fed to dairy cows has a big impact on productivity, so accessing the variation of the Total Mixed Ration (TMR) is vital.


During September, Rumenco organised a UK wide roadshow of on-farm TMR audits which focused on ways dairy farmers can improve feed consistency. The audits were carried out by Francisco Ysunza, the European Technical Support Manager for Diamond V, who have close ties with Rumenco in the UK.


Ensuring consistency is a key consideration for farmers feeding a TMR, explains Dr Alison Bond, Rumenco’s Commercial Nutritionist. “The food down the feed passage is the main input into a dairy cow and ensuring that every bite is the same is crucial for performance.”


The TMR audit also realises the investment made by the nutritionist and farmer into the ration. “One farm audited during Francisco’s visit, with a herd of 800 cows, with 670 in-milk, was putting upwards of a million pounds worth of feed and forage products into the feeder wagon over the course of a year. This equates to nearly £3.50 per cow per day.


“If you're making this investment, you really need to ensure that the bespoke formulation of the ration is what the cows are actually eating day in, day out, to maximise the investment.”


Francisco highlighted that the way the TMR is prepared and presented in the feed passage is the missing link between the ration formulation and the cow’s digestion of it.


TMR audit


The TMR audit process involves undertaking a whole feeding management assessment, and in some cases, this goes as far as measuring the quality of each of the ration components to ensure they are up to scratch. During the recent roadshow, Francisco undertook a TMR audit that purely assessed the ration preparation protocol and then used a Penn State Shaker Box (PSSB) to assess the consistency.


The PSSB is a tool originally designed to measure the distribution of different sized particles within the TMR and determine its average quality. However, in a TMR Audit, the PSSB allows measurements of the variation among samples of feed offered to a batch of cows. It also allows for immediate on-farm results.


The feed is screened into particles large enough to promote chewing and rumination, through to the smaller inclusions that are prone to pass to the ‘true stomach’, the abomasum.  


Dr Bond says that for a TMR audit to be accurate and offer tangible recommendations for improvements, it needs to be carried out correctly. “There is a set procedure for a TMR audit, and this must be followed to get repeatable, significant results.


“The first step is to monitor the loading of the wagon; looking at the inclusion order, the mixing times, and the accuracy of the weighing,” Dr Bond adds.


“As a rule of thumb, farms should have a specific loading protocol decided with their nutritionist that they religiously stick too. In most situations the general order is to start with dry, high fibre inclusions through to finishing with the wet ingredients.”


Francisco explained that this is the best solution for the lowest TMR variation whilst also being practical on-farm.


Following monitoring the mixing of the ration, the audit then involves taking 10 samples from the feed passage immediately after the wagon has delivered the feed. Approximately 500g of TMR should be collected per sample down the entire length of the feed passage and put in a one litre sealable bag. 


Dr Bond adds, “By taking 10 samples it represents the ration presented to cows at 10 different locations. The point is that the TMR should be consistent across the intake of the whole batch fed.”


The samples are then all individually analysed through the process of shaking the PSSB.  The same person needs to shake all the samples to ensure audit consistency. Each sample is put through a rigorous method of eight turns, with five shakes each, during which time the ration will separate out down the trays by particle size.


The volume of feed in each of the trays is then weighed and this is recorded. “The percentage weight in each tray is determined and it’s the coefficient of variation among the different samples in the batch that is analysed, not the average,” explains Dr Bond.


“The target is 3% variation or less; the most important variation to consider is the biggest percentage of diet, as this represents the largest volume of feed the cow is eating.”


Audit results


One of the farms audited was particularly concerned about over processing the ration and the potential for inconsistencies. They mixed a half load for the treatment group and fresh calvers, versus a full load for the main milking group.


The audit confirmed that the half load did show inconsistencies in the feed presented to the cows, with 9.3% variation. This was compared to 5.2% variation for the full load. Francisco’s advice to combat this inconsistency was to pre-mix the dry and finely ground ingredients with the low density (light) dry fibre sources to make up enough for two full loads. This could then be split out and used to feed the main group and the treatment group separately as usual, but reducing the variation on the smaller group.


One of the farmers who had an audit carried out was concerned about their mixing time; however, the audit established there wasn’t a problem with the mixing time after the last ingredient. One thing highlighted was that feeder wagons vary, depending on mixing capacity, and type of mixing, be it horizontal or vertical. Farmers using vertical augers should mix at a minimum of 30 RPM and ensure there are no ‘dead spots’ in the wagon, explained Francisco.


Where a TMR tracker is used, this can ensure loading accuracy and reduce any variation caused by different staff mixing the TMR. “It’s reassuring for the staff, to know that their TMR procedures are working well,” adds Dr Bond.


Refusal


It is important to monitor the refusal levels, and for this reason it forms another component of the TMR audit, explains Dr Bond. “You are aiming to have a bit left over, so the cows are never looking for food, but you don’t want to waste quantities of food, so best practice is to monitor the refusal every day.


“Besides sampling the fresh TMR, we take 5 samples from the refusal still at the passage in the morning before being cleared away. This is to establish the level of sorting which is a natural behaviour of the cow.”

She adds. “It’s a fine line when mixing the ration, between the need to process the ration enough so the cow can’t sort and reject, and not over processing it. By assessing the refusals you can monitor the amount of selection going on.”


If the audit highlights the need for any changes, another piece of advice offered by Francisco was that, if you make changes to the amount of diet offered to cows to try and match their intake, make a small change and then keep it stable for at least one more day and monitor the response. Too many changes make it impossible to balance the cows’ diet and consequently the gut. 


This is relevant across the board adds Dr Bond. “Any recommendations for small tweaks to the TMR, albeit loading order or mixing times, make then one step at a time so the impact can be assessed.”


Dr Bond says that there are many benefits to be gained from ensuring consistency in the ration, not just realising the investment made in the ration components in the first instance. “The research done by Diamond V across a large number of TMR audits, both in the States and across Europe including the UK, has shown improvements in many aspects of dairy cow productivity and performance, especially yield.”

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