Given the dismal forage and grain situation for crop year 2012, Heather and I thought it appropriate to include a summary of our low starch research trial that she just presented at ADSA. With corn grain prices predicted to be near record high and in some areas forage yields at critical lows; how best to make milk?
Last year, we conducted a feeding trial comparing a conventional 26% starch diet to low 21% starch diets by using two basic feeding strategies to lower dietary starch:
1. Increase the forage-to-concentrate ratio with highly digestible forage fiber.
2. Replace starch from corn grain with non-forage fiber sources (NFFS) that are high in digestible fiber.
The study was a 3 x 3 Latin square design with 2 1-day periods. Each cow received each diet and thereby served as her own control. The study included 15 peak- to mid-lactation multiparous cows, (6 ruminally cannulated). The dietary treatments were:
The NFFS for this trial were: beet pulp, wheat midds and DDGS. Soy hulls is another option for NFFS but was not used in this trial.
Diet formulation and nutrient profiles are presented in Table 1.
The results for intake and milk production are presented in Table 2. Dry matter intake (DMI) was slightly greater on the CON ration. In spite of lower DMI of the FOR and NFFS diets, higher NDF content of these diets resulted in significant differences in intake of aNDF and peNDF. Gut fill may have been approaching a maximum, possibly limiting DMI of these two diets. The 24-hour NDFD of these diets was surprisingly similar, though numerically higher for the CON ration. Intake of aNDF was 1.23, 1.35 and 1.34% of body weight for the CON, FOR, and NFFS diets respectively. Milk production was similar between the CON and NFFS diets at about 112 lbs, but was significantly lower on the high forage ration. Milk fat content differed across diets, but component corrected milk was similar. Milk true protein did not differ between diets. These results indicate that diets with NFFS can maintain similar milk production when substituted for starch in the form of cornmeal. Increasing the level of dietary forage, however, showed a slight decrease in milk yield but similar FCM yield.
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