Silage Insights - Nutritional Value

	Source: istockphotos

Research into the nutritional value of silage indicates that when properly made, with the right materials and machinery, and correctly stored, baled silage can show same or better quality, with fewer nutrient losses than either silage clamp or silo.

A well-made bale can have the advantage that less air is trapped than in a silage clamp or silo and, following the introduction of bale choppers, the cattle have little trouble tearing out mouthfuls of the baled product, leading to increased fodder intake and milk yields.

Same or better quality

Given the same grass and the same care, bale silage quality will be the same as or better than clamp silage. To compare the quality, the grass needs to be the same cut and given the same care. However, bale silage is often made from the second, third or fourth cuts, which are generally of lower quality than the first cut. Poor handling and storage can also affect the quality of silage. Correctly made, baled silage can be the most successfully conserved forage as it has a fibre content and straw length that stimulates the appetite and rumination.

Low nutrient losses

Losses of net energy are inevitable during the fermentation of sugar to lactic acid. However all other losses such as residual respiration, silage effluents, mal-fermentation and aerobic reactions during storage and extraction can be avoided to a great extent.

Research by Per Lingvall at the Swedish University of Agricultural Science in Uppsala revealed that high quality bale silage only loses about 5% of its dry matter content. A prerequisite for this standard is its wrapping with six layers of white film and silage making according to well-established recommendations.

“In Sweden nutrient losses differ between systems,” observes Per Lingvall. “In a perfect world, when the crops are wilted to an optimal DM content for the different systems” 30% for bunker silos, 35 – 45% for tower silos, and 50% for bales – no effluent losses occur. However, in practice, during storage and unloading a tower or a bunker silo, average nutrient losses are calculated at 10 – 15% in a tower and 15 – 20% in a bunker silo, compared with 3 – 5% in a tightly wrapped bale with six layers of white high quality stretch film.”

Increased fodder intake and milk yields

Bale silage is ideal for farms with relatively low fodder requirements. The daily feed rate would not be sufficient to keep losses small in clamp silos. This is particularly the case for horse keepers or for small-to-medium livestock farmers. Bale silage can also be given as supplementary feed in the stable after grazing.

If animals are always fed with fresh silage, their fodder intake increases and as a consequence the milk yields increase as well. The table below shows the impact on fodder uptake by dairy cows caused by the duration of interim storage after extraction from the silo.

Impact of interim storage on fodder uptake
Sample	Day	Day 1			Day 2
	Time	7:00	13:00	19:00	7:00	19:00
Duration of storage	h	Fodder extraction	6	12	24	36
NEL / kg dry matter	MJ	6.6	6.3	6.0	5.7	5.4
Fodder uptake per animal and day	kg dry matter	11.1	10.4	9.8	9.1	8.8
		100 %	94 %	88 %	82 %	79 %
Energy uptake per animal and day	MJ NEL	73	66	59	52	48
		100 %	90 %	81 %	71 %	66 %
is sufficient for ... kg milk	kg	11.5	9.2	7.0	4.9	3.6
yeasts	cbu/g	103	103	105	107	108
cbu = colony building units NEL= Netto Energy Lactation MJ = Mega-Joule

Source: Hoffmann, M., and Richardt, W., 2003: Remarks about ensiling.