Masters Theses

Date of Award

12-1980

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Karl M. Barth

Committee Members

J.B. McLaren, R.N. Heitman

Abstract

Two total-collection trials were conducted to determine the nutrient digestibility and nitrogen utilization of caged layer excreta-corn stover silages treated with or without silage additives. In trial 1, silages were produced from 18 or 30% excreta, 50% corn stover and various amounts of water to achieve a 50% moisture silage, and fed to 12 mature wether sheep.

The pH, after ensiling, was 4.6 for the 18% excreta silage and 5.0 for the 30% excreta silage. The 18% excreta and the 30% excreta silages contained: 48.8 and 45.8% dry matter; and on a dry matter basis, 10.5 and 14.0% crude protein; 1.30 and 1.69% ether extract; 29.2 and 28.5% crude fiber; 8.2 and 11.8% ash; 50.9 and 44.2% nitrogen-free extract; 46.2 and 46.4% acid-detergent fiber; and 4.57 and 7.18 mg/g uric acid, respectively. Dry matter intake of the 18% excreta silage was 1.17 kg/day and was similar to the 1.15 kg/day of the 30% excreta silage. Apparent digestion coefficients for the 18% and the 30% excreta silages were: dry matter, 46.4 and 47.1%; organic matter, 48.9 and 49.8%; crude protein, 59.4 and 65.2%; ether extract, 71.5 and 75.2%; crude fiber, 47.6 and 50.0%; nitro gen-free extract, 46.9 and 43.8%; and acid-detergent fiber, 35.0 and 36.5%, respectively. Total digestible nutrients were 46.1 for the 18% excreta silage and 45.5 for the 30% excreta silage. Dry matter, organic matter, crude fiber and acid-detergent fiber digestibilities were similar across treatment (p>.05). A significant increase in the digestibility of crude protein (p<.01) and ether extract (p<.05) was found for the 30% excreta silage while the 18% excreta silage supported higher (p<.05) nitrogen-free extract digestibility.

The nitrogen intake, nitrogen retention, true nitrogen digestibility, absorbed nitrogen retained, intake nitrogen retained, net protein utilization and net protein value of the 18% excreta silage were 19.7 g/day, 8.51 g/day, 85.09%, 50.42%, 9.77%, 36.06% and 4.51%, respectively, while for the 30% excreta silage they were 25.6 g/day, 1.94 g/day, 84.68%, 9.80%, -22.85%, 8.36% and 1.17%, respectively. The nitrogen intake was higher (p<.01) for the 30% excreta silage. All of the other nitrogen utilization parameters except true nitrogen digestibility were significantly higher (p<.01) for the 18% excreta silage. The true nitrogen digestibility was similar (p>.05) for both silages.

In trial 2, 16 wether sheep were used to determine the effect of silage additives on fermentation of excreta silage, nutrient digestibility and nitrogen utilization. The silage treatments were: no additives (control), Silabac (a bacterial additive), phosphoric acid (an acid additive) or the combination of Silabac and phosphoric acid. The level of excreta used in this trial was 22.5%; the corn stover was 50% of the ensiling material and again water was added to produce a 50% moisture silage.

The nutritional composition of the silages was quite variable. The dry matter of the silages treated with no additives (control), Silabac, phosphoric acid or the combination of the latter two was 58.4, 53.5, 55.2 and 61.6%, respectively; other nutrients, on a dry matter basis were: crude protein, 9.2, 8.6, 8.4 and 10.1%; ether extract, 1.22, 0.96, 0.85 and 1.20%; crude fiber, 27.9, 28.0, 36.4 and 28.2%; ash 12.5, 11.4, 9.4 and 15.2%; nitrogen-free extract, 49.1, 51.1, 51.0 and 44.8%; acid-deterent fiber, 42.5, 42.4, 45.0 and 40.9% and uric acid 5.98, 3.30, 3.63 and 9.38 mg/g, respectively.

Dry matter intake was 1.22, 0.97, 0.98 and 1.14 kg/day for the silages containing no additives, Silabac, phosphoric acid and the combination of both additives, respectively. Apparent digestion coefficients for these silages were: dry matter, 36.9, 40.8, 39.6 and 42.2%; organic matter, 40.7, 42.8, 45.0 and 44.2%; crude protein, 47.5, 40.5,31.3 and 45.9%; ether extract, 66.0, 58.8, 66.0 and 75.6%; crude fiber, 39.5, 44.1, 47.6 and 43.4%; nitrogen-free extract, 41.8, 46.4, 45.4 and 43.5%; and acid-detergent fiber, 33.3, 31.1, 37.1 and 36.2%, respectively. Total digestible nutrients were 37.7, 40.8, 41.8 and 38.5% for these silages, respectively. Dry matter digestibility was higher (p<.01) for the additive treated silages than that of the control silage although the organic matter digestibility was similar for all silages. The crude protein digestibility was higher (p<.05) for the Silabac treated silage than that of the phosphoric acid silage. However, ether extract digestibility was higher (p<.05) for the phosphoric acid silage than that of the silage treated with Silabac. Silage made with the combination of additives had higher (p<.01) ether extract digestibility than the mean of Silabac and phosphoric acid silages. Crude fiber digestibility was higher (p<.05) for all the treated silages while there were no differences among treated silages (p<.10). Conversely, phosphoric acid treated silages supported higher (p<05) acid-detergent fiber digestibility than that of the Silabac treated silage but the control silage and the mean of the additive treated silages had similar acid-detergent fiber digestibility (p<.10). Total digestible nutrients were higher (p<.05) with the additive treated silages than the control silage. A higher TDN (p<.05) was obtained when the additives were used singly rather than in combination.

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