Maximise milk from forage to lift income over feed costs this winter

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Length: 1074 words; 5-6 minutes

Hands holding silage image

According to data from Trouw Nutrition, average grass silage quality is generally higher than in 2014, with increased digestibility, energy content and crude protein coupled with lower levels of digestible fibre. But unless correctly balanced with carefully targeted additional feeds, then at least some of that feed value is going to be lost, warns KW nutritionist Mark Scott.

“Balancing nutrient supply to the rumen, and the cow, will be critical if both the value extracted from forage and the all  important income over feed costs (IOFC) are to be maximised,” he adds.

Increased acidosis risk

A particularly good growing year for cereals – UK winter wheat harvest up 10-12% compared to the ADAS ten-year average, winter barley up 11-14% – also means reduced prices and the temptation to feed higher levels in the ration, particularly with the current depressed milk price. The danger is an increased risk of acidosis or sub-acute ruminal acidosis (SARA), which will compromise fibre digestion in the rumen and reduce milk from forage.

“…a higher IOFC isn’t achieved by simply using cheaper feed or less feed…”

“More milk from forage and a higher IOFC isn’t achieved by simply using cheaper feed or less feed, but by fine tuning feed choices to complement the nutrients in forage as accurately as possible,” Mr Scott highlights.

“High quality, low fibre silages and plenty of low-cost cereals may seem a huge bonus with milk prices still depressed, but both can exaggerate any energy imbalance in the rumen. Unless that balance is maintained, the result will be a reduction in fermentation efficiency and more nutrients lost as waste – any fibre or grains clearly visible in the manure mean the rumen is definitely not balanced!”

Essential ration sugars

Sugars are an essential part of this balance, driving microbial breakdown of forage fibre in the rumen, yet the residual sugars in preserved forages aren’t particularly accessible, Mr Scott points out.

“The majority of rations also fall short of the 5% additional sugar research from the US has identified as being beneficial in driving microbial activity,” he adds. “So feeding extra sugars is critical, typically in the form of 2.0-2.5kg /cow/day of a traditional high sugar liquid feed or around 6kg of a low dry matter product such as whey permeate.”

The fast rate of energy release from high sugar liquid feeds complements that from starch and digestible fibre to create a sustained supply of energy to support optimal microbial activity (figure 1). This leads to a greater proportion of the nutrients in home grown forage being fully utilised. Including sugars in the ration also maximises capture of the high levels of effective rumen degradable protein (ERDP) in grass silages, since energy to incorporate this protein into microbial growth is available almost immediately after each meal.

Rumen energy release graph
Figure 1 – Rate of energy release in the rumen for a range of different feeds – Click to enlarge

 

Liquid feed solution

However, dry feeds, whether traditional straights or alternative co-product feeds, don’t contain the levels of available sugar required to lift the overall diet above the 5% threshold (table 1). What’s needed is one of the various liquid feeds based on molasses or whey permeate, which not only contain 42-74% sugars, but also have  a very low substitution rate – the extra sugar can be added to the ration with minimal displacement of other feed ingredients and will even stimulate additional forage intake.

Table 1 – Comparison of high-sugar straights (dry matter basis)

 

Dry matter
(%)

Energy
(MJ ME/kg DM)

Sugar
(%)

Starch
(%)

Cane molasses

73

12.7

64

trace

Molale

60

13.5

42

Rouxminate

66

13.0

60

LactoBoost (whey permeate)

23

13.5

74*

Citrus pulp (pellets)

92

12.3

24

trace

Confectionery blends (e.g. SweetStarch, SugaRich Dairy, Formula 1)

87-89

14.5-15.5

15-23

30-37

Sugar beet feed (molassed)

89

12.5

20

1.0

Breakfast cereal blends (eg Kellogs No. 1)

93

14.0

18

52

* Sugar as lactose

“The ideal balance of energy supply in the rumen requires a starch-to-sugars ratio of around 3:1,” adds Mr Scott. “Introduce additional sugars slowly, allowing time for the rumen to adapt, and consider the sources of starch in the ration – feeding a range of starch sources helps avoid overloading the rumen and triggering SARA, which will compromise fibre digestion.

“More slowly released starch sources such as maize meals or cooked breakfast cereals will help reduce the SARA risk. And consider treating cereals with caustic soda – whether made on-farm or bought in ready to feed – to create an alkaline feed that will help buffer rumen pH.”

Increasing feed efficiency

As well as avoiding SARA, which occurs when the rumen drops below pH 5.5, the aim should be to minimise the time spent under pH5.8, as this is the point at which fibre digestion starts to be compromised.

“So if you have high quality silages and are looking to include more cereals in the ration, it may well be worth adding a live yeast or rumen conditioner to help maintain the correct rumen pH,” Mr Scott adds. “In fact, recent research has shown a benefit in using a combination product containing both, increasing feed conversion efficiency over using the yeast alone by reducing the time rumen content spent at low pH (figure 2).”

Vistacell AB pH advantage graph
Figure 2: Effect of yeast alone (Vistacell) or yeast-plus-buffer (Vistacell AB) on rumen pH in lactating dairy cows (Source: Schothorst Feed Research, 2014) – Click to enlarge

Other strategies to minimise rumen pH depression include ensuring rations contain at least 0.5kg/cow/day of chopped wheat straw to promote rumination and production of saliva (a powerful rumen buffer), and supplying some of the energy in the ration as digestible fibre.

“…if rumen buffering…then sugar beet feed remains the more effective option.”

“The competitive price of soya hulls is making them a popular choice for the winter, though if rumen buffering is the priority, then sugar beet feed remains the more effective option,” Mr Scott advises. “Many co-product moist feeds like Traffordgold also contain predominantly digestible fibre energy.

“They also tend to offer better value than their dry equivalents – replacing 2.75kg of parlour compound with 5kg of Traffordgold, for example, will save 15p/cow/day.”

Avoiding rumen overload

And if extra energy is needed to support high yields, Mr Scott suggests the strategic use of rumen-protected fats to avoid overloading the rumen with additional starch. The key is to target its use in cows that will produce a financial return on the money spent even at current milk prices, typically high yielders and those in early lactation.

“If correctly targeted, many protected fats still offer a greater return on investment than traditional feeds,” he states. “In early lactation, for example, the inclusion of a 100% fat like Goldenflake at 300g/cow/day supplies the same energy as almost 1kg of rolled wheat, but without overloading the rumen.”

Goldenflake image
A 100% rumen-protected fat, Goldenflake can raise yields by up to 2 litres/cow/day.

This can raise yields by up to 2 litres/cow/day, as well as lifting butterfat content by up to 0.2% for a possible increase in milk value and income. It’s also proven to reduce the mobilisation of body reserves, leading to improvements in fertility, which is a key driver for future herd profitability.

“It’s this absolute attention to detail rather than ill-considered feed cutbacks that is the key to protecting IOFC when the milk price is low, both now and in the coming months,” Mr Scott highlights. “So make optimising rumen function the top priority this winter, and aim to squeeze every ounce of feed value from the silages made during the summer, control feed costs per litre and maximise your IOFC.”

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