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Effect of ensiling on the feeding value of flint corn grain for feedlot beef cattle: A meta-analysis

ABSTRACT

The objective of this study was to review the effect of ensiling on the feeding value of flint corn grain and performance of feedlot cattle. In this meta-analysis, ensiled corn grain included both high-moisture corn and rehydrated corn grain. The criteria for a publication enter in the database were: diet was offered as a total mixed ration, diet contained at least 300 g/kg dry matter (DM) of ensiled or dry corn grain, and ensiled grain contained a minimum of 280 g/kg of moisture. The final dataset included 21 paired comparisons from eight publications, from 2002 to 2019. A sub dataset of digestibility trials contained six paired comparisons for starch digestibility and five paired comparisons for DM digestibility. The outcomes were compared using the Mixed procedure of SAS, including a random effect of comparison within study (paired comparison). Ensiling corn grain increased total-tract digestibility of DM (+4.59%) and starch (+3.33%), decreased DM intake by 14.1% (10.3 and 8.85 kg/d for dry and ensiled, respectively) and metabolizable energy intake by 4.39%, but did not affect average daily gain (1.61 and 1.58 kg/d for dry and ensiled corn, respectively). Therefore, ensiling corn grain increased feed efficiency by 18.3% (0.164 and 0.194, for dry and ensiled, respectively). The feeding value was on average 25.7% higher for ensiled corn grain compared with dry corn grain. Ensiling is an efficient strategy to improve the caloric value of flint corn grain for finishing cattle.

corn grain silage; high moisture corn; reconstituted corn grain

1. Introduction

Corn grain is the main energy source in US (Samuelson et al., 2016Samuelson, K. L.; Hubbert, M. E.; Galyean, M. L. and Loest, C. A. 2016. Nutritional recommendations of feedlot consulting nutritionists: The 2015 New Mexico State and Texas Tech University survey. Journal of Animal Science 94:2648-2663. https://doi.org/10.2527/jas.2016-0282
https://doi.org/10.2527/jas.2016-0282...
) and Brazilian (Oliveira and Millen, 2014Oliveira, C. A. and Millen, D. D. 2014. Survey of the nutritional recommendations and management practices adopted by feedlot cattle nutritionists in Brazil. Animal Feed Science and Technology 197:64-75. https://doi.org/10.1016/j.anifeedsci.2014.08.010
https://doi.org/10.1016/j.anifeedsci.201...
) beef feedlot diets. Meanwhile, corn hybrids cultivated in Brazil are predominantly flint, with a higher proportion of vitreous endosperm than dent hybrids predominant in the US and other countries with temperate climate. Comparing Brazilian and US corn kernels, Correa et al. (2002)Correa, C. E. S.; Shaver, R. D.; Pereira, M. N.; Lauer, J. G. and Kohn, K. 2002. Relationship between corn vitreousness and ruminal in situ starch degradability. Journal of Dairy Science 85:3008-3012. https://doi.org/10.3168/jds.S0022-0302(02)74386-5
https://doi.org/10.3168/jds.S0022-0302(0...
reported a higher proportion of vitreous endosperm for Brazilian (average 0.731) than for US hybrids (average 0.482).

Beyond the pericarp barrier, endosperm vitreousness is negatively related to starch digestibility (Correa et al., 2002Correa, C. E. S.; Shaver, R. D.; Pereira, M. N.; Lauer, J. G. and Kohn, K. 2002. Relationship between corn vitreousness and ruminal in situ starch degradability. Journal of Dairy Science 85:3008-3012. https://doi.org/10.3168/jds.S0022-0302(02)74386-5
https://doi.org/10.3168/jds.S0022-0302(0...
). The protein matrix (prolamines) sunrounding the starch granules is insoluble in water and hinders the action of ruminal microorganisms and their enzymes in the ruminal environment and intestinal digestion (McAllister et al., 1993McAllister, T. A.; Phillippe, R. C.; Rode, L. M. and Cheng, K. J. 1993. Effect of the protein matrix on the digestion of cereal grains by ruminal microorganisms. Journal of Animal Science 71:205-212. https://doi.org/10.2527/1993.711205x
https://doi.org/10.2527/1993.711205x...
; Huntington, 1997Huntington, G. B. 1997. Starch utilization by ruminants: from basics to the bunk. Journal of Animal Science 75:852-867. https://doi.org/10.2527/1997.753852x
https://doi.org/10.2527/1997.753852x...
; Ngonyamo-Majee et al., 2008Ngonyamo-Majee, D.; Shaver, R. D.; Coors, J. G.; Sapienza, D. and Lauer, J. G. 2008. Relationship between kernel vitreousness and dry matter degradability for diverse corn germplasm. II. Ruminal and post-ruminal degradabilities. Animal Feed Science and Technology 142:259-274. https://doi.org/10.1016/j.anifeedsci.2007.09.001
https://doi.org/10.1016/j.anifeedsci.200...
). Additionally, flint hybrids with higher proportion of vitreous endosperm are harder to break down during physical processing (Philippeau and Michalet-Doreau, 1997Philippeau, C. and Michalet-Doreau, B. 1997. Influence of genotype and stage of maturity of maize on rate of ruminal starch degradation. Animal Feed Science and Technology 68:25-35. https://doi.org/10.1016/S0377-8401(97)00042-4
https://doi.org/10.1016/S0377-8401(97)00...
), which might worsen starch digestion.

Ensiling high moisture or rehydrated corn grain is a strategy to improve starch digestibility (Owens et al., 1986Owens, F. N.; Zinn, R. A. and Kim, Y. K. 1986. Limits to starch digestion in the ruminant small intestine. Journal of Animal Science 63:1634-1648. https://doi.org/10.2527/jas1986.6351634x
https://doi.org/10.2527/jas1986.6351634x...
; Benton et al., 2005Benton, J. R.; Klopfenstein, T. J. and Erickson, G. E. 2005. Effects of corn moisture and length of ensiling on dry matter digestibility and rumen degradable protein. Nebraska Beef Cattle Reports. p.31-33. University of Nebraska, Lincoln.). During the storage period, the action of proteolytic bacteria and kernel proteases break down the protein matrix (Junges et al., 2017Junges, D.; Morais, G.; Spoto, M. H. F.; Santos, P. S.; Adesogan, A. T.; Nussio, L. G. and Daniel, J. L. P. 2017. Short communication: Influence of various proteolytic sources during fermentation of reconstituted corn grain silages. Journal of Dairy Science 100:9048-9051. https://doi.org/10.3168/jds.2017-12943
https://doi.org/10.3168/jds.2017-12943...
), increasing the availability of starch to animal digestion (Hoffman et al., 2011Hoffman, P. C.; Esser, N. M.; Shaver, R. D.; Coblentz, W. K.; Scott, M. P.; Bodnar, A. L.; Schmidt, R. J. and Charley, R. C. 2011. Influence of ensiling time and inoculation on alteration of the starch-protein matrix in high-moisture corn. Journal of Dairy Science 94:2465-2474. https://doi.org/10.3168/jds.2010-3562
https://doi.org/10.3168/jds.2010-3562...
).

For dent corn hybrids, several reviews have shown benefits of ensiling corn grain for feedlot cattle, but in a lesser extension than steam flaking (Owens et al., 1997Owens, F. N.; Secrist, D. S.; Hill, W. J. and Gill, D. R. 1997. The effect of grain source and grain processing on performance of feedlot cattle: a review. Journal of Animal Science 75:868-879. https://doi.org/10.2527/1997.753868x
https://doi.org/10.2527/1997.753868x...
; Zinn et al., 2011Zinn, R. A.; Barreras, A.; Corona, L.; Owens, F. N. and Plascencia, A. 2011. Comparative effects of processing methods on the feeding value of maize in feedlot cattle. Nutrition Research Reviews 24:183-190. https://doi.org/10.1017/S0954422411000096
https://doi.org/10.1017/S095442241100009...
). Owens and Basalan (2013)Owens, F. N. and Basalan, M. 2013. Grain processing: gain and efficiency responses by feedlot cattle. p.76-100. In: Proceedings of the Plains Nutrition Council 2013 Spring Conference. Amarillo, TX. reported lower dry matter intake (DMI, −5.5%) without decreasing average daily gain (ADG) for ensiled corn compared with dry rolled corn. Therefore, the ensiled grain had grater value of net energy for gain (NEg, +6.7%) and improved feed efficiency (+5.4%) in comparison with dry rolled corn.

For flint corn grain, however, the extent of the benefit is not well stablished; meanwhile, the use of grain silages has been steeply increasing in the last decade in Brazil (Bernardes and Castro, 2019Bernardes, T. and Castro, T. 2019. Silages and roughage sources in the Brazilian beef feedlots. Journal of Animal Science 97(Supplement 3):411. https://doi.org/10.1093/jas/skz258.815
https://doi.org/10.1093/jas/skz258.815...
; Daniel et al., 2019Daniel, J. L. P.; Bernardes, T. F.; Jobim, C. C.; Schmidt, P. and Nussio, L. G. 2019. Production and utilization of silages in tropical areas with focus on Brazil. Grass and Forage Science 74:188-200. https://doi.org/10.1111/gfs.12417
https://doi.org/10.1111/gfs.12417...
). Considering that integrating data through meta-analysis is an effective approach to summarize results from multiple studies (St-Pierre, 2001St-Pierre, N. R. 2001. Invited Review: Integrating quantitative findings from multiple studies using mixed model methodology. Journal of Dairy Science 84:741-755. https://doi.org/10.3168/jds.S0022-0302(01)74530-4
https://doi.org/10.3168/jds.S0022-0302(0...
), our objective was to review controlled trials and quantify the effects of ensiling on the feeding value of flint corn grain, diet energy intake, and performance of feedlot cattle.

2. Material and Methods

2.1. Literature search and inclusion criteria

The database was created with published data from paired comparisons between ensiled corn grain (high moisture corn and rehydrated corn) and dry corn grain (ground or rolled) in diets for feedlot beef cattle. Our literature search used Google Scholar, PubMed, ScienceDirect, Scirus, CAB, and Portal Periódicos CAPES, investigation of references listed in papers, and contact with researchers in the field. The search included the following keywords: high moisture corn, high moisture maize, rehydrated corn, rehydrated maize, reconstituted corn, reconstituted maize, ensiled corn grain, or ensiled maize grain.

The inclusion criteria were as follows: diet was offered as a total mixed ration, diet contained at least 300 g/kg dry matter (DM) of ensiled or dry corn grain, and ensiled grain contained a minimum of 280 g/kg of moisture, because the moisture content affects the conservation process, digestibility, and energy value of corn grain silage (Owens and Basalan, 2013Owens, F. N. and Basalan, M. 2013. Grain processing: gain and efficiency responses by feedlot cattle. p.76-100. In: Proceedings of the Plains Nutrition Council 2013 Spring Conference. Amarillo, TX.; Gomes et al., 2018Gomes, A. L. M.; Bueno, J. L.; Jacovaci, F. A.; Bolson, D. C.; Jobim, C. C. and Daniel, J. L. P. 2018. Effects of processing, moisture, and length of storage on the fermentative losses and ruminal degradability of reconstituted corn grain silage. p.500-501. In: Proceedings of XVIII International Silage Conference. Bonn, Germany.). Nine publications were found, but one failed to attain our criterium for minimum moisture content of ensiled corn (Carareto, 2011Carareto, R. 2011. Fontes de nitrogênio, níveis de forragem e métodos de processamento de milho em rações para tourinhos da raça Nelore terminados em confinamento. Tese (D.Sc.). Universidade de São Paulo, Escola Superior de Agricultura “Luiz de Queiroz”, Piracicaba.). The final dataset included five full articles (Costa et al., 2002Costa, C.; Arrigoni, M. B.; Silveira, A. C. and Oliveira, H. N. 2002. Desempenho de bovinos superprecoces alimentados com silagem de milho ou feno de aveia e grãos de milho ensilados ou secos. Acta Scientiarum. Animal Sciences 24:1175-1183. https://doi.org/10.4025/actascianimsci.v24i0.2585
https://doi.org/10.4025/actascianimsci.v...
; Silva et al., 2007Silva, S. L.; Leme, P. R.; Putrino, S. M.; Valinote, A. C.; Nogueira Filho, J. C. M. and Lanna, D. P. D. 2007. Milho grão seco ou úmido com sais de cálcio de ácidos graxos para novilhos Nelore em confinamento. Revista Brasileira de Zootecnia 36:1426-1434. https://doi.org/10.1590/S1516-35982007000600028
https://doi.org/10.1590/S1516-3598200700...
; Henrique et al., 2007Henrique, W.; Beltrame Filho, J. A.; Leme, P. R.; Lanna, D. P. D.; Alleoni, G. F.; Coutinho Filho, J. L. V. and Sampaio, A. A. M. 2007. Avaliação da silagem de grão de milho úmido com diferentes volumosos para tourinhos em terminação. Desempenho e características de carcaça. Revista Brasileira de Zootecnia 36:183-190. https://doi.org/10.1590/S1516-35982007000100022
https://doi.org/10.1590/S1516-3598200700...
; Caetano et al., 2015Caetano, M.; Gourlart, R. S.; Silva, S. L.; Drouillard, J. S.; Leme, P. R. and Lanna, D. P. D. 2015. Effect of flint corn processing method and roughage level on finishing performance of Nellore-based cattle. Journal of Animal Science 93:4023-4033. https://doi.org/10.2527/jas.2015-9051
https://doi.org/10.2527/jas.2015-9051...
; Caetano et al., 2019Caetano, M.; Goulart, R. S.; Rizzo, P. M.; Silva, S. L.; Drouillard, J. S.; Leme, P. R. and Lanna, D. P. D. 2019. Impact of flint corn processing method and dietary starch concentration on finishing performance of Nellore bulls. Animal Feed Science and Technology 251:166-175. https://doi.org/10.1016/j.anifeedsci.2019.03.006
https://doi.org/10.1016/j.anifeedsci.201...
) and three theses (Silva, 2015Silva, M. R. H. 2015. Processamento e ensilagem no valor nutritivo de grãos de milho para novilhos em confinamento. Tese (D.Sc.). Universidade Estadual de Maringá, Maringá.; Silva, 2016Silva, N. C. 2016. Características das silagens de grãos de milho influenciadas pela reidratação e pela inoculação com L. buchneri sobre o desempenho de bovinos de corte confinados. Tese (D.Sc.). Universidade Estadual Paulista, Jaboticabal.; Jacovaci, 2019Jacovaci, F. A. 2019. Silagem de grãos de milho para bovinos de corte: Estudo de aditivo nutricional da ensilagem sobre desempenho animal e análise de dados de híbridos americanos vs brasileiros. Tese (D.Sc.). Universidade Estadual de Maringá, Maringá.), totaling 21 paired comparisons. Nellore bulls were used in five studies, whereas Santa Gertrudes bulls, Simental × Nellore bulls, or Angus × Charolais bulls were used in other three studies.

The main dataset included performance traits, such as DMI, initial body weight (BW), final BW, ADG, feed efficiency, carcass dressing, energy calculations, and feeding value. A sub dataset included apparent digestibility of DM and starch.

2.2. Calculations

When the publications did not present data for feed efficiency, this variable was calculated as ADG/DMI. Diet net energy was estimated using the equations proposed by Zinn and Shen (1998)Zinn, R. A. and Shen, Y. 1998. An evaluation of ruminally degradable intake protein and metabolizable amino acid requirements of feedlot calves. Journal of Animal Science 76:1280-1289. https://doi.org/10.2527/1998.7651280x
https://doi.org/10.2527/1998.7651280x...
, using individual DMI and ADG data. Energy requirement for gain was calculated as: Eg (MJ/d) = 4.184 × (0.0493 × ((BW × 478/FW)0.75) × ADG1.097), in which BW is mean body weight, 478 is standard reference weight, and FW is final weight. Energy requirement for maintenance was calculated as: Em (MJ/d) = 4.184 × 0.077 × BW0.75. Diet net energy for maintenance was estimated by the equation: NEm (MJ/kg DM) = 4.184 × ((−b − (b2 − 4ac)0.5)/2a), in which: a = −0.877 × DMI, b = (0.877 × (Em/4.184)) + (0.41 × DMI) + (Eg/4.184) and c = −0.41 × (Em/4.184). Diet net energy for gain was calculated as: NEg (MJ/kg DM) = 4.184 × ((0.877 × (NEm/4.184)) − 0.41). Diet metabolizable energy was calculated as: ME (MJ/kg DM) = ((23.8573 × NEm/4.184 + 2.3974 × (NEm/4.184)2 + 24.7761) × 0.0362) × 4.184, whereas ME intake (MJ/d) was computed as ME × DMI.

The feeding value (FV) of ensiled corn relative to dry corn grain was calculated as (Bremer et al., 2011Bremer, V. R.; Watson, A. K.; Liska, A. J.; Erickson, G. E.; Cassman, K. G.; Hanford, K. J. and Klopfenstein, T. J. 2011. Effect of distillers grains moisture and inclusion level in livestock diets on greenhouse gas emissions in the corn-ethanol-livestock life cycle. The Professional Animal Scientist 27:449-455.): FV (%) = ((((feed efficiency observed for ensiled corn grain diet − feed efficiency observed for dry corn grain diet)/feed efficiency observed for dry corn grain diet)/proportion of ensiled corn grain in the corresponding diet) + 1) × 100.

2.3. Statistical analysis

Data were analyzed using the statistical software SAS (Statistical Analysis System, version 9.4). Mean, standard deviation, minimum and maximum values, skewness, and kurtosis were calculated using the MEANS procedure. Animal outcomes were compared using the MIXED procedure. The model included a random effect of paired comparison within study and a fixed effect of grain processing (ensiled or dry). The covariance matrix structure used was the unstructured (UN). Due to different experimental designs and accuracy of the experiments used, data were weighted by the standard error of the mean or by the number of experimental units (when the standard error of the mean was not available in all studies) using the WEIGHT statement in the MIXED procedure (St-Pierre, 2001St-Pierre, N. R. 2001. Invited Review: Integrating quantitative findings from multiple studies using mixed model methodology. Journal of Dairy Science 84:741-755. https://doi.org/10.3168/jds.S0022-0302(01)74530-4
https://doi.org/10.3168/jds.S0022-0302(0...
; Sauvant et al., 2008Sauvant, D.; Schmidely, P.; Daudin, J. J. and St-Pierre, N. R. 2008. Meta-analyses of experimental data in animal nutrition. Animal 2:1203-1214. https://doi.org/10.1017/S1751731108002280
https://doi.org/10.1017/S175173110800228...
).

The difference of ME intake in dry and ensiled corn grain diets adjusted by a random effect of study was regressed against ME intake in dry corn diet adjusted by a random effect of study (both obtained by the mixed model described above) and correlated with the proportion of forage NDF and grain in diet using the REG procedure. A bar graph was contructed with the feeding value of ensiled corn grain relative to dry corn grain.

3. Results

Diet characteristics and animal performance traits had a large range of values, indicating that the dataset covered a great part of practical situations in Brazilian beef feedlots (Table 1). The moisture content of ensiled corn grain varied from 300 to 399 g/kg, and dietary inclusion of corn grain (dry or ensiled) ranged from 380 to 798 g/kg DM, encompassing most of practical conditions in feedlots using corn grain silage. Forage level and concentration of forage neutral detergent fiber (NDF) ranged from 50.0 to 500 g/kg DM and 32.0 to 260 g/kg DM, respectively. The dataset had a predominance of Nellore cattle, with a wide variation in BW at the beginning of the feeding trials (from 236 to 438 kg).

Table 1
Dataset used in the data analysis

No differences were observed for initial and final BW (Table 2). Ensiling corn grain decreased DMI by 14.1% (P<0.01) and ME intake by 4.39% (P<0.01), without affecting ADG (P = 0.21). Compared with diets containing dry corn, diets balanced with ensiled corn increased feed efficiency by 18.3% (P<0.01). Replacing dry with ensiled corn did not change carcass dressing (P = 0.61).

Table 2
Performance of feedlot beef cattle fed flint dry or ensiled corn grain

Total tract apparent digestibility of DM and starch were increased by 4.59 (P<0.01) and 3.33% (P<0.01), respectively, when the ensiled grain replaced the dry grain. The feeding value was on average 25.7% higher for the ensiled corn grain compared with the dry corn grain (Figure 1). Difference of ME intake upon replacing dry with ensiled corn was negatively correlated with ME intake (Figure 2).

Figure 1
Feeding value (%) of ensiled corn grain relative to dry corn grain (assumed 100%), adjusted for a random effect of comparison within study and weighted by the number of experimental units.

Bars are ordered by ensiled corn grain feeding value. Each gray bar represents one comparison. The black bar indicates mean (126%) and 95% confidence interval (121 to 134%).


Figure 2
Relationship between the difference of metabolizable energy (ME) intake in ensiled and dry corn-based diets and the ME intake in dry corn-based diet, adjusted for a random effect of comparison and weighted by the number of experimental units.

Difference of ME intake = 194 – 1.75 × ME intake in dry corn diet; P<0.01, R2 = 0.96, RMSE = 1.30.


4. Discussion

Grain processing methods to reduce particle size or alter the protein matrix in kernel endosperm have been successfully used at farm level to increase the extent of grain digestion. In Brazil, the use of corn grain silage in feedlots, either rehydrated (reconstituted) or high moisture corn, is steeply increasing (Bernardes and Castro, 2019Bernardes, T. and Castro, T. 2019. Silages and roughage sources in the Brazilian beef feedlots. Journal of Animal Science 97(Supplement 3):411. https://doi.org/10.1093/jas/skz258.815
https://doi.org/10.1093/jas/skz258.815...
; Daniel et al., 2019Daniel, J. L. P.; Bernardes, T. F.; Jobim, C. C.; Schmidt, P. and Nussio, L. G. 2019. Production and utilization of silages in tropical areas with focus on Brazil. Grass and Forage Science 74:188-200. https://doi.org/10.1111/gfs.12417
https://doi.org/10.1111/gfs.12417...
).

As expected, replacing dry corn with ensiled corn in finishing diets increased starch and DM digestibility. During the storage period, the action of proteolytic bacteria and kernel proteases broke down the protein matrix (Junges et al., 2017Junges, D.; Morais, G.; Spoto, M. H. F.; Santos, P. S.; Adesogan, A. T.; Nussio, L. G. and Daniel, J. L. P. 2017. Short communication: Influence of various proteolytic sources during fermentation of reconstituted corn grain silages. Journal of Dairy Science 100:9048-9051. https://doi.org/10.3168/jds.2017-12943
https://doi.org/10.3168/jds.2017-12943...
), increasing the availability of starch (Hoffman et al., 2011Hoffman, P. C.; Esser, N. M.; Shaver, R. D.; Coblentz, W. K.; Scott, M. P.; Bodnar, A. L.; Schmidt, R. J. and Charley, R. C. 2011. Influence of ensiling time and inoculation on alteration of the starch-protein matrix in high-moisture corn. Journal of Dairy Science 94:2465-2474. https://doi.org/10.3168/jds.2010-3562
https://doi.org/10.3168/jds.2010-3562...
) both in the rumen and in the small intestine (Owens et al., 1986Owens, F. N.; Zinn, R. A. and Kim, Y. K. 1986. Limits to starch digestion in the ruminant small intestine. Journal of Animal Science 63:1634-1648. https://doi.org/10.2527/jas1986.6351634x
https://doi.org/10.2527/jas1986.6351634x...
; Owens et al., 1997Owens, F. N.; Secrist, D. S.; Hill, W. J. and Gill, D. R. 1997. The effect of grain source and grain processing on performance of feedlot cattle: a review. Journal of Animal Science 75:868-879. https://doi.org/10.2527/1997.753868x
https://doi.org/10.2527/1997.753868x...
). Hence, diets based on ensiled corn had higher energy contents (ME, NEm, NEg) than diets based on dry corn.

Replacing dry corn with ensiled corn markedly decreased DMI. In diets with high proportion of concentrates, replacing dry corn with corn grain silage frequently decreases DMI (Owens et al., 1997Owens, F. N.; Secrist, D. S.; Hill, W. J. and Gill, D. R. 1997. The effect of grain source and grain processing on performance of feedlot cattle: a review. Journal of Animal Science 75:868-879. https://doi.org/10.2527/1997.753868x
https://doi.org/10.2527/1997.753868x...
; Zinn et al., 2011Zinn, R. A.; Barreras, A.; Corona, L.; Owens, F. N. and Plascencia, A. 2011. Comparative effects of processing methods on the feeding value of maize in feedlot cattle. Nutrition Research Reviews 24:183-190. https://doi.org/10.1017/S0954422411000096
https://doi.org/10.1017/S095442241100009...
), because higher ruminal starch fermentability induces hypophagia. Greater starch fermentability is associated with higher production and absorption of volatile fatty acids in the forestomach, including propionate (Oba and Allen, 2003Oba, M. and Allen, M. S. 2003. Effects of corn grain conservation method on feeding behavior and productivity of lactating dairy cows at two dietary starch concentrations. Journal of Dairy Science 86:174-183. https://doi.org/10.3168/jds.S0022-0302(03)73598-X
https://doi.org/10.3168/jds.S0022-0302(0...
). Therefore, a higher net portal flux of propionate likely occurs in diets with ensiled corn compared with dry corn. In the liver, a high propionate offer increases the anaplerosis in the tricarboxylic acid cycle (oxidation of fuels) and ATP production, which causes satiety mainly by decreasing meal size (Allen et al., 2009Allen, M. S.; Bradford, B. J. and Oba, M. 2009. Board-invited review: the hepatic oxidation theory of the control of feed intake and its application to ruminants. Journal of Animal Science 87:3317-3334. https://doi.org/10.2527/jas.2009-1779
https://doi.org/10.2527/jas.2009-1779...
; Allen, 2020Allen, M. S. 2020. Review: Control of feed intake by hepatic oxidation in ruminant animals: integration of homeostasis and homeorhesis. Animal 14:s55-s64. https://doi.org/10.1017/S1751731119003215
https://doi.org/10.1017/S175173111900321...
). Jacovaci (2019)Jacovaci, F. A. 2019. Silagem de grãos de milho para bovinos de corte: Estudo de aditivo nutricional da ensilagem sobre desempenho animal e análise de dados de híbridos americanos vs brasileiros. Tese (D.Sc.). Universidade Estadual de Maringá, Maringá. observed a decreased meal size in animals fed corn grain silage compared with dry rolled corn. In our meta-analysis, the reduction in DMI (−14.1%) was larger than previously reported for dent corn (−5.5%; Owens and Basalan, 2013Owens, F. N. and Basalan, M. 2013. Grain processing: gain and efficiency responses by feedlot cattle. p.76-100. In: Proceedings of the Plains Nutrition Council 2013 Spring Conference. Amarillo, TX.).

Although the ensiled corn decreased DMI, the ADG was similar between diets, which led to a marked improvement in feed efficiency (+18.3%) when ensiled corn replaced dry corn. For dent hybrids, Owens and Basalan (2013)Owens, F. N. and Basalan, M. 2013. Grain processing: gain and efficiency responses by feedlot cattle. p.76-100. In: Proceedings of the Plains Nutrition Council 2013 Spring Conference. Amarillo, TX. also reported improvements in feed efficiency in favor of ensiled corn, but to a lesser extent (+5.4%). Based on feed efficiency, the feeding value was on average 25.7% higher for the ensiled corn grain compared with the dry flint corn grain. It means that NE values of flint corn grain silage were markedly higher (i.e., +20.7% for NEm and +27.7% for NEg) than dry flint corn (ground or rolled). Previous studies have suggested that NE of dry ground flint corn is lower than tabular values in nutritional models (e.g., NRC, 1996NRC - National Research Council. 1996. Nutrient requirements of beef cattle. 7th ed. (2000 update). National Academies Press, Washington, DC.; NASEM, 2016NASEM - National Academies of Sciences, Engineering, Medicine. 2016. Nutrient requirements of beef cattle. 8th ed. National Academies Press, Washington, DC.). Pereira et al. (2007)Pereira, E. M.; Santos, F. A. P.; Nussio, L. G.; Pedroso, A. M.; Costa, D. F. A.; Imaizumi, H. and Bittar, C. M. M. 2007. Estimativa de energia metabolizável de rações com polpa cítrica em substituição ao milho para tourinhos em terminação. Revista Brasileira de Zootecnia 36:216-224. https://doi.org/10.1590/S1516-35982007000100026
https://doi.org/10.1590/S1516-3598200700...
reported similar or slightly lower values of NEm and NEg for diets based on dry ground flint corn compared with diets based on citrus pulp. Assuming the value of NEg for dry ground flint corn equal to that of citrus pulp listed in NRC (1996)NRC - National Research Council. 1996. Nutrient requirements of beef cattle. 7th ed. (2000 update). National Academies Press, Washington, DC. (5.62 MJ/kg DM), ensiling corn grain may increase the NEg to 7.18 MJ/kg DM. In a review, Zinn et al. (2011)Zinn, R. A.; Barreras, A.; Corona, L.; Owens, F. N. and Plascencia, A. 2011. Comparative effects of processing methods on the feeding value of maize in feedlot cattle. Nutrition Research Reviews 24:183-190. https://doi.org/10.1017/S0954422411000096
https://doi.org/10.1017/S095442241100009...
reported a value of 6.74 MJ/kg DM for ensiled dent corn. These values are comparable to NEg of steam-flaked dent corn (6.98 MJ/kg DM) listed in NASEM (2016)NASEM - National Academies of Sciences, Engineering, Medicine. 2016. Nutrient requirements of beef cattle. 8th ed. National Academies Press, Washington, DC..

Meanwhile, ME intake slightly decreased when ensiled corn replaced dry corn. However, the difference of ME intake (ensiled grain minus dry grain) was dependent on ME intake. When ME intake of dry corn-based diet was higher than 111 MJ/d, the replacement of dry with ensiled grain decreased ME intake, whereas in animals with lower caloric intake (≤111 MJ/d), ensiled corn improved ME intake. Krehbiel et al. (2006)Krehbiel, C. R.; Cranston, J. J. and McCurdy, M. P. 2006. An upper limit for caloric density of finishing diets. Journal of Animal Science 84:E34-E49. https://doi.org/10.2527/2006.8413_supplE34x
https://doi.org/10.2527/2006.8413_supplE...
reported a curvilinear relationship between dietary content of ME and ADG, which reflects ME intake. In that case, the maximum ME intake was approximatly 118 MJ/d (ME content of 13.2 MJ/kg × average DMI of 8.91 kg/d). Such value is slightly higher than the 111 MJ/d capable of reverting the benefit of replacing dry with ensiled grain on ME intake in our meta-analysis. In our review, there was a predominance of Nellore cattle (Bos taurus indicus), whereas in US trials reviewed by Krehbiel et al. (2006)Krehbiel, C. R.; Cranston, J. J. and McCurdy, M. P. 2006. An upper limit for caloric density of finishing diets. Journal of Animal Science 84:E34-E49. https://doi.org/10.2527/2006.8413_supplE34x
https://doi.org/10.2527/2006.8413_supplE...
, there was a predominance of B. taurus taurus cattle. Bos taurus cattle have been claimed to have a greater capacity of consuming energy relative to their maintenance requirements than B. indicus, especially in diets with high levels of concentrates (Olbrich Jr., 1996; Krehbiel et al., 2000Krehbiel, C. R.; Kreikemeier, K. K. and Ferrell, C. L. 2000. Influence of Bos indicus crossbreeding and cattle age on apparent utilization of a high-grain diet. Journal of Animal Science 78:1641-1647. https://doi.org/10.2527/2000.7861641x
https://doi.org/10.2527/2000.7861641x...
; Carvalho et al., 2016Carvalho, J. R. R.; Chizzotti, M. L.; Schoonmaker, J. P.; Teixeira, P. D.; Lopes, R. C.; Oliveira, C. V. R. and Ladeira, M. M. 2016. Performance, carcass characteristics, and ruminal pH of Nellore and Angus young bulls fed a whole shelled corn diet. Journal of Animal Science 94:2451-2459. https://doi.org/10.2527/jas.2015-0162
https://doi.org/10.2527/jas.2015-0162...
; Favero et al., 2019Favero, R.; Menezes, G. R. O.; Torres, R. A. A.; Silva, L. O. C.; Bonin, M. N.; Feijó, G. L. D.; Altrak, G.; Niwa, M. V. G.; Kazama, R.; Mizubuti, I. Y. and Gomes, R. C. 2019. Crossbreeding applied to systems of beef cattle production to improve performance traits and carcass quality. Animal 13:2679-2686. https://doi.org/10.1017/S1751731119000855
https://doi.org/10.1017/S175173111900085...
; Antonelo et al., 2020Antonelo, D. S.; Gómez, J. F. M.; Goulart, R. S.; Beline, M.; Cônsolo, N. R. B.; Corte, R. R. S.; Silva, H. B.; Ferrinho, A. M.; Pereira, A. S. C.; Gerrard, D. E. and Silva, S. L. 2020. Performance, carcass traits, meat quality and composition of non-castrated Nellore and crossbred male cattle fed soybean oil. Livestock Science 236:104059. https://doi.org/10.1016/j.livsci.2020.104059
https://doi.org/10.1016/j.livsci.2020.10...
).

Nutritional strategies capable of increasing ME intake in diets based on ensiled corn would benefit beef operations handling zebu cattle. One practical strategy is altering the site of starch digestion, from rumen to intestine, to decrease the hypophagic effect of propionate, for instance by including more NDF from forage or byproducts in the diet. Owens and Basalan (2013)Owens, F. N. and Basalan, M. 2013. Grain processing: gain and efficiency responses by feedlot cattle. p.76-100. In: Proceedings of the Plains Nutrition Council 2013 Spring Conference. Amarillo, TX. reported an increase of ME intake when more NDF was added to diets based on ensiled corn, as well as a decrease in the level of ensiled corn. On the other hand, Caetano et al. (2015Caetano, M.; Gourlart, R. S.; Silva, S. L.; Drouillard, J. S.; Leme, P. R. and Lanna, D. P. D. 2015. Effect of flint corn processing method and roughage level on finishing performance of Nellore-based cattle. Journal of Animal Science 93:4023-4033. https://doi.org/10.2527/jas.2015-9051
https://doi.org/10.2527/jas.2015-9051...
and 2019) reported no interaction between corn processing method (dry ground or ensiled corn) and diet proportions of forage NDF or starch, respectively. In our dataset, neither the proportion of forage NDF (r = 0.16, P = 0.48) nor grain proportion in diet (r = −0.09, P = 0.68) were significantly correlated with the difference in ME intake upon replacing dry grain with ensiled grain.

Owens and Basalan (2013)Owens, F. N. and Basalan, M. 2013. Grain processing: gain and efficiency responses by feedlot cattle. p.76-100. In: Proceedings of the Plains Nutrition Council 2013 Spring Conference. Amarillo, TX. reported that the dilution of the diet energy would be more beneficial with ensiled corn grain than with the other forms of grain processing. Therefore, an option for changing the pattern of starch digestion is to partially replace ensiled corn with dry ground corn (e.g., 1/4 or 1/3 of dry ground). Stock and Erickson (2006)Stock, R. A. and Erickson, G. E. 2006. Associative effects and management-combinations of processed grains. p.166-172. In: Proceedings of Cattle Grain Processing Symposium, Tulsa, OK. summarized trials from Nebraska to evaluate the associative effects of feeding mixtures of ensiled and dry corn in high-grain diets. Blends of 250 to 330 g/kg of dry corn and 750 to 670 g/kg of ensiled corn produced a positive associative effect of improved cattle performance compared with only dry corn or ensiled corn or other blends. Meanwhile, more studies are warranted to fine-tune those nutritional adjustments for flint corn grain offered to zebu cattle.

5. Conclusions

Ensiling is a efficient strategy to improve the caloric value of flint corn grain for finishing cattle. The feeding value is on average 25.7% higher for the ensiled corn grain compared with the dry corn grain.

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Publication Dates

  • Publication in this collection
    03 Mar 2021
  • Date of issue
    2021

History

  • Received
    22 May 2020
  • Accepted
    21 Oct 2020
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