Effect of the ratio of zinc amino acid complex to zinc sulfate on the performance of Holstein cows.

Multiparous (n=70) and primiparous (n=66) Holstein cows were balanced by 305-d previous mature-equivalent milk yield and parity and assigned to 1 of 3 dietary treatments to evaluate the ratio of zinc sulfate to zinc amino acid complex (CZ) in pre- and postpartum Holstein cows fed diets containing 75 mg of added zinc/kg. Treatments were (1) 75 mg of supplemental zinc/kg of dry matter (DM) provided entirely as zinc sulfate (0-CZ); (2) 0-CZ diet, except 33.3 mg of zinc sulfate/kg of DM in the prepartum and 15.5mg of zinc sulfate/kg of DM in the postpartum diet were replaced by CZ from Availa-Zn (16-CZ; Zinpro Corp., Eden Prairie MN); and (3) 0-CZ diet, except 66.6 mg of zinc sulfate/kg of DM in the prepartum and 40.0 mg of zinc sulfate/kg of DM in the postpartum diet was replaced by Availa-Zn (40-CZ). Cows were housed at the Iowa State University Dairy Farm and were individually offered a total mixed ration containing dietary treatments beginning at 28 ± 15 d before expected calving date until 250 d in milk. Relative to 0-CZ, multiparous cows (but not primiparous) fed CZ (16-CZ or 40-CZ) had increased (20%) colostrum IgG concentrations. Prepartum DM intake (DMI) was decreased with CZ supplementation. Postpartum DMI was decreased in cows fed CZ, whereas milk yield (MY) was increased in the 40-CZ-fed cows relative to those fed both 0-CZ and 16-CZ. Feed efficiency increased linearly when measured as MY/DMI, 3.5% fat-corrected MY/DMI, and solids-corrected MY/DMI. Regardless of level, feeding CZ decreased services per conception. Feeding 16-CZ decreased milk fat concentration and feeding CZ linearly increased milk urea nitrogen concentration. In summary, supplementing zinc as a mixture of CZ and zinc sulfate, as opposed to supplementing only zinc sulfate, has beneficial effects on production parameters in dairy cows, with those benefits becoming more apparent as the ratio of CZ to zinc sulfate increases.

The effect of Lactobacillus buchneri on the fermentation, aerobic stability and ruminal degradability of maize silage.

AIMS: To evaluate the effect of Lactobacillus buchneri, heterofermentative lactic acid bacteria (LAB), on the fermentation, aerobic stability and ruminal degradability of whole-crop maize silages under laboratory conditions. Two homofermentative LAB were tested for the purpose of comparison. METHODS AND RESULTS: Maize was harvested at early dent [290 g kg(-1) dry matter (DM)] and one-half milk line (355 g kg(-1) DM) stages. Both homofermentative LAB were applied at 1 x 10(5) CFU g(-1) of fresh forage. Lactobacillus buchneri was applied at 1 x 10(5), 5 x 10(5) and 1 x 10(6) CFU g(-1) of fresh forage. Silages with no additives served as control. After treatment, the chopped forages were ensiled in 1.5-l anaerobic jars. Three jars per treatment were sampled on day 60. After 60 days of storage, silages were subjected to an aerobic stability test lasting for 5 days, in which CO(2) production, as well as chemical and microbiological parameters, was measured to determine the extent of aerobic deterioration. Both homofermentative LAB increased the concentration of lactic acid and the numbers of yeasts, and decreased the concentration of acetic acid and impaired the aerobic stability of silages. In contrast, applying L. buchneri decreased the concentration of lactic acid and increased the concentration of acetic acid of the silages. Under aerobic conditions, silages treated with 5 x 10(5) and 1 x 10(6) CFU g(-1) of L. buchneri, had lower pH, CO(2) production and the numbers of yeasts than the silages treated with 1 x 10(5) CFU g(-1) of L. buchneri (P < 0.05). However, all doses of L. buchneri and both homofermentative LAB did not affect in situ rumen DM, organic matter and neutral detergent fibre degradability of the silages. CONCLUSIONS: Lactobacillus buchneri was very effective in protecting maize silages exposed to air under laboratory conditions. All doses of L. buchneri, especially 5 x 10(5) CFU g(-1) or more, markedly decreased the numbers of yeasts and improved the aerobic stability of silages. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of L. buchneri, as a silage inoculant, can improve the aerobic stability of maize silages by inhibition of yeast activity.

The effects of Propionibacterium acidipropionici and Lactobacillus plantarum, applied at ensiling, on the fermentation and aerobic stability of low dry matter corn and sorghum silages.

The aim of this work was to study the effects of applying a strain of Propionibacterium acidipropionici, with or without Lactobacillus plantarum, on the fermentation and aerobic stability characteristics of low dry matter (DM) corn (Zea mays L.) and sorghum (Sorghum bicolor L.) silages. Corn at the dent stage and sorghum at the flowering stage were harvested. Treatments comprised control (no additives), P. acidipropionici, L. plantarum and a combination of P. acidipropionici and L. plantarum. Fresh forages were sampled prior to ensiling. Bacterial inoculants were applied to the fresh forage at 1.0 x 10(6) colony-forming units per gram. After treatment, the chopped fresh materials were ensiled in 1.5-l anaerobic glass jars equipped with a lid that enabled gas release only. Three jars per treatment were sampled on days 2, 4, 8, 16 and 60 after ensiling, for chemical and microbiological analysis. At the end of the ensiling period, 60 days, the silages were subjected to an aerobic stability test. The L. plantarum inoculated silages had significantly higher levels of lactic acid than the controls, P. acidipropionici and combination of P. acidipropionici and L. plantarum inoculated silages (P<0.05). The P. acidipropionici did not increase propionic and acetic acid levels of the silages. After the aerobic exposure test, the L. plantarum and combination of P. acidipropionici and L. plantarum had produced more CO2 than the controls and the silages inoculated with P. acidipropionici (P<0.05). All silages had high levels of CO2 and high numbers of yeasts and molds in the experiment. Therefore, all silages were deteriorated under aerobic conditions. The P. acidipropionici and combination of P. acidipropionici and L. plantarum were not able to improve the aerobic stability of fast-fermenting silages, because they could not work well in this acidic environment. The results showed that P. acidipropionici and combination of P. acidipropionici and L. plantarum did not improve the aerobic stability of low DM corn and sorghum silages, which are prone to aerobic deterioration.

The effect of Propionibacterium acidipropionici, with or without Lactobacillus plantarum, on the fermentation and aerobic stability of wheat, sorghum and maize silages.

AIMS: To determine the effect of Propionibacterium acidipropionici, alone or in combination with Lactobacillus plantarum, on the fermentation and aerobic stability of wheat, sorghum and maize silages. METHODS AND RESULTS: The inoculants were applied at 1.0 x 10(6) CFU g(-1). Silages with no additives served as control. Fresh forages were sampled prior to ensiling. Three jars per treatment were sampled on days 2, 4, 8, 16 and 60 after ensiling, for chemical and microbiological analysis. At the end of the ensiling period, the silages were subjected to an aerobic stability test. The P. acidipropionici-inoculated silages had significantly higher levels of acetic and propionic acid than the L. plantarum or P. acidipropionici + L. plantarum-inoculated silages (P < 0.05). Therefore, yeast activity was impaired in the P. acidipropionici-inoculated silages. As a result, P. acidipropionici decreased CO(2) production and improved aerobic stability of wheat, sorghum and maize silages. However, the combination of P. acidipropionici + L. plantarum did not improve aerobic stability of the silages. CONCLUSIONS: The P. acidipropionici was very effective in protecting the wheat, sorghum and maize silages exposed to air under laboratory conditions, probably because the acidic environment under ensiling conditions is favourable for this micro-organism. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of P. acidipropionici, as a silage inoculant can improve the aerobic stability of silages by inhibition of yeast activity.