Evaluation of an amylase-enabled corn silage in lactating cows
Open Access
- Author:
- Cueva Welchez, Sergio
- Graduate Program:
- Animal Science
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 05, 2021
- Committee Members:
- Adele Turzillo, Program Head/Chair
Alexander Nikolov Hristov, Thesis Advisor/Co-Advisor
Tara L Felix, Committee Member
Kevin John Harvatine, Committee Member - Keywords:
- amylase-enabled corn silage
enteric methane
dairy cow - Abstract:
- An experiment was conducted to investigate the effects of an amylase-enabled corn silage on the lactation performance, enteric gas emission and rumen fermentation of lactating dairy cows. The amylase-enabled corn hybrid (Enogen; Syngenta Seeds LLC) was harvested, ensiled, and included in the diet at 40% of dry matter (DM) of the cows. The Enogen corn silage (ECS) was compared with silage from a control (CON) isogenic corn hybrid without the amylase trait. Both silages were included at the same inclusion rate of dietary DM and the diet fed, with exception of the silage source, was identical between the treatments. The purpose of the experiment was to investigate the effect of ECS on lactational performance, enteric gas emission, and rumen fermentation of lactating dairy cows. Both corn hybrids were grown for approximately 130 d, and silages were fermented for approximately 220 d before the beginning of the animal experiment in April 2019. At harvest, the CON hybrid yielded approximated 1.1 t of DM/ha more than the ECS hybrid. Crude protein concentration was 6% lesser in ECS when compared with the CON hybrid. Acid detergent fiber was also 3.9% lesser for ECS. Furthermore, the ECS was greater in starch content, when compared with the CON (9.3%, on average). As expected, the amylase activity in ECS was 13-fold greater when compared with the CON silage. Nevertheless, the differences mentioned in the nutritional content of the silages, did not result in major differences in fermentation end-products between the silages. Inclusion of ECS at 40% dietary DM did not affect DMI but increased MY (40.8 vs 38.8 kg/d), improved feed efficiency (1.55 vs. 1.47 kg/kg) and tended to improve energy-corrected milk yield (ECM) feed efficiency in lactating cows (1.50 vs. 1.45 kg/kg). Milk lactose was greater (4.92 vs 4.86 %) for cows fed the ECS diet, relative to CON, but milk protein and fat contents were similar. Methane emission intensity (per unit of milk yield) was decreased by the ECS diet compared with CON; however, treatment did not affect CH4 emission intensity expressed per kilogram of ECM. Rumen fermentation, apart from a decreased molar proportion of butyrate in rumen fluid of ECS-fed cows, was not affected by treatment. Amylase activity was numerically, but not statistically, greater in rumen fluid of ECS-fed cows, however, the difference could be related both to a greater amylase activity in ECS (as previously described) and greater starch intake with the ECS diet, when compared with CON. As suspected, intake of starch was greater in cows fed the ECS diet relative to CON, and apparent total-tract DM digestibility also tended to be greater in cows fed the ECS. There were no differences in intakes in any of the other nutrients or their apparent total-tract digestibility. Nitrogen intake and utilization, as well as urinary purine derivative excretion, were not affected by the silage treatment. Effects induced by ECS were likely a result of the greater starch content in ECS and greater overall availability of digestible nutrients. Moreover, given that ECS decreased CH4 emission intensity (per unit of MY, but not of ECM), data would suggest that the carbon footprint of milk production could be reduced by inclusion of ECS, Inclusion of an amylase-enabled hybrid in dairy rations showed promising effects by improving feed efficiency and ECM feed efficiency in dairy cows. However, the amylase-enabled corn silage used in the current experiment tended to have a greater overall availability of digestible nutrients and was greater in starch content, when compared with its isogenic counterpart. In this regard, effects observed on cow performance can be attributed, at least partially, to differences in silage nutritional composition. Research investigating the effects of feeding amylase-enabled corn silages to dairy cows is limited. This makes it challenging to concretely determine the mode and extent of action of the amylase enzyme in the current study. Thus, future research on amylase-enabled hybrids should be focused on determining modes and stages of action of the enzyme, potential nutritional and environmental benefits in dairy cows, and possible interactions with other additives or dietary ingredients. The amylase-enabled technology seems to be promising, however, questions remain that must be answered to fully understand the benefits of the inclusion of amylase-enabled corn in dairy cow diets.