Supplementation during the mid-gestation period of Nellore cows: calf ingestive behaviorABSTRACT.
The objective of this study was to evaluate the ingestive behavior of calves born to Nellore cows subjected to protein supplementation during the middle third of gestation. In phase I, 20 cows were used, and the study spanned the entire middle third of gestation. The cows were divided into two groups: supplemented and unsupplemented. The supplement contained 40% CP and 78% TDN, provided at 0.5 kg animal-1 day-1 to maintain a BCS between 5 and 6. Phase II began after calving and ended at 240 days postpartum. Ingestive behavior was evaluated for 24h on the 120th day of life, with observations made every five minutes. Data were statistically interpreted through analysis of variance and the F-test at a significance level of 0.05, in a completely randomized design, using the SAEG statistical software. Supplementation had no effect on the ingestive behavior of the calves. Discrete bouts and rumination parameters showed no differences; however, among the bite-related variables, biting rate and number of bites per day differed statistically. Protein supplementation during the middle third of gestation did not influence calf ingestive behavior, except for bite-related variables.
Keywords:
bovine; ethology; fetal programming; offspring
Introduction
Meat production plays a crucial role in the global economy, contributing significantly to trade at local, national, and international levels (Ghotbaldini et al., 2018). During the middle and final thirds of gestation, pregnant cows managed in extensive systems face nutritional challenges (Rodrigues et al., 2021), strongly associated with environmental seasonality. In this context, nutritional strategies for pregnant cows can be an effective strategy to mitigate the negative effects of seasonality on the productive performance of cows and their offspring (Costa et al., 2021).
Gestational supplementation indicates that several factors may act during this developmental stage, leading to long-term changes in growth, fetal development, organ systems, and metabolic functions. The timing and duration of these factors determine future outcomes, which vary according to the specific tissue or organ developing at that moment (Abuelot, 2020; Caton et al., 2019). This approach has been investigated worldwide as a means of improving intake, digestibility, performance, and carcass quality in offspring.
Ingestive behavior can be described as a set of activities that are key for animal assessment, and understanding it is highly valuable in ruminant production and its interaction with the rearing environment. In grazing cattle, the main daily activities include grazing, rumination, and resting, with the proportion of time expended on each depending on pasture characteristics, climate, nutritional needs, and management (Pereira et al., 2018; Santos et al., 2020; Dias-Silva & Filho, 2021).
Feeding patterns in cattle tend to persist, although they are strongly influenced by the environment. Variability among individuals may occur within the herd (Naeve et al., 2018), and assessing ingestive behavior provides information about the nutritional, social, and health status of the group.
Visual assessment of three of the most common actions in grazing situations-chewing, prehension, and combined chewing-prehension-is widely used to monitor ruminant feeding (Deniz et al., 2017). Feeding time is negatively associated with dietary neutral detergent fiber content and positively associated with dry matter intake (Custodio et al., 2017).
In selection and management, some indicators are more commonly used as quality markers, the most important being body weight (Fernandes et al., 2020). The search for additional techniques and parameters to evaluate animal efficiency has driven numerous scientific studies aimed at broadening selection methods and promoting optimal development from early life stages.
Thus, the objective was to evaluate the ingestive behavior of calves born to Nellore cows subjected to fetal nutrition during the middle third of gestation.
Material and methods
The Ethics Committee on the Use of Animals (CEUA) of the State University of Piauí (UESPI) evaluated and approved the project (approval no. 0033/2017).
The field phase was conducted at Fazenda Uberlândia, located in the municipality of Parnaguá, in the Cerrado region of the state of Piauí, Brazil. According to the Köppen classification, the climate is tropical seasonal sub-humid dry (Aw). The study area comprised 20 ha, separately cultivated with Massai grass (Panicum maximum cv. Massai) and Mandante grass (Echinochloa polystachya), subdivided into eight paddocks.
This study was divided into two phases: supplementation of the dams, and the calf pre-weaning period.
The cows were weighed, identified, treated for ecto- and endoparasites (Doramectin - 200 mcg kg-1), and allocated into two groups of 10 animals each: cows receiving protein concentrate supplementation; cows without protein concentrate supplementation. Both groups had free access to mineral salt and water.
In phase I, 20 third-parity Nellore cows were subjected to fixed-time artificial insemination (FTAI), and pregnancy was confirmed by ultrasound 45 days after insemination. Phase I began at the end of the first third of gestation and continued through the middle third, with supplementation provided for 90 days.
The concentrate supplement was supplied daily at 10:00 in uncovered, double-access collective plastic troughs with a linear space of 70 cm animal-1. The supplement (Table 1) was formulated according to nutritional requirements (Valadares Filho, 2016), containing 40% CP and 78% TDN, and provided at 0.5 kg per animal per day to maintain a BCS between 5 and 6 (scale of 1 to 9).
The second phase corresponded to the calf pre-weaning stage and involved the dams and their offspring. This phase began at birth and ended 240 days later. The two treatments from phase I were maintained, using 10 replicates: calves from cows receiving protein concentrate supplementation; and calves from cows without protein concentrate supplementation. Both treatments had free access to mineral salt and water ad libitum.
After birth, the umbilical cord was cut, and a 10% iodine solution was applied to the calves. The newborns were weighed and identified with ear tags for subsequent evaluations.
Pasture was assessed in both phases of the experiment on the first day and every 30 days thereafter. Dry matter availability was estimated according to total extraction method. To minimise the influence of biomass variation between paddocks, cows were kept in each paddock and randomly transferred to another every eight days, following the experimental design.
Pasture samples were weighed, and a composite sample of forage from grazed and ungrazed paddocks was obtained. The samples were manually separated into leaf blade, stem, and dead material fractions, which were weighed to determine their proportions and then stored in labelled plastic bags at −10 °C for later chemical analysis (Table 1).
To determine biomass accumulation in paddocks kept closed for 30 days as exclusion areas, the triple-pairing technique was used. Dry matter accumulation during each experimental period was calculated by multiplying the daily accumulation rate (DAR) by the number of days in the period.
The daily dry matter accumulation rate (DAR) was estimated using the equation proposed by Campbell (1966): DAR = (Gi - Fi−1) / n, where DAR = daily dry matter accumulation rate in period j, in kg DM ha-1 day-1; Gi = average final dry matter of the four empty paddocks at time i, in kg DM ha-1; Fi−1 = average initial dry matter in the empty paddocks at time i−1, in kg DM ha-1; and n = number of days in period j.
Potentially digestible dry matter (pdDM) of the pasture was estimated by the equation: pdDM = 0.98 (100 - %NDF) + (%NDF - %iNDF), where 0.98 is the true digestibility coefficient of cell contents, NDF = neutral detergent fiber, and iNDF = indigestible NDF. The availability of potentially digestible DM (pdDMA) was calculated as pdDMA = TDMA × pdDM, where pdDMA = availability of potentially digestible DM, in kg ha-1; TDMA = total DM availability, in kg ha-1; and pdDM = potentially digestible DM, in percentage.
Forage allowance (FA) was calculated using the equation of Prohmann et al. (2004): FA = {(DRB × area + DAR × area) / BWtotal} × 100, where FA = forage allowance, in kg DM per 100 kg BW day-1; DRB = daily total residual biomass, in kg DM ha-1 day-1; DAR = daily accumulation rate, in kg DM ha-1 day-1; and BWtotal = total body weight of animals, in kg ha-1.
The stocking rate (SR) was calculated considering the animal unit (AU) as 450 kg of body weight (BW), using SR = AUt / Area, where SR = stocking rate, in AU ha-1; AUt = total animal units; and Area = total experimental area, in hectares.
For forage collection by simulated grazing, the animals in each treatment were observed during grazing to determine the height of the grazed stratum. A forage sample was then collected, aiming to reproduce the characteristics of the forage consumed by the animals, according to Johnson (1978).
Laboratory analyses were conducted at the Animal Nutrition Laboratory of the State University of Piauí (UESPI), Corrente/PI campus. Analyses of dry matter (DM), ash (MM), crude protein (CP), ether extract (EE), and acid detergent fiber (ADF) in concentrate and forage samples were performed according to Detmann et al. (2012).
Neutral detergent fiber corrected for ash and protein (NDFap) was estimated following Licitra et al. (1996). Non-fibrous carbohydrates (NFC) were calculated as proposed by Hall (2003): 100 − [%CP − %CP derived from urea + %urea + %NDFap + %EE + %ash].
Total digestible nutrients (TDN) were calculated according to Sampaio et al. (2025), using NDF and NFC corrected for ash and protein, by the formula: TDN (%) = DCP + DNDFap + DNFCap + 2.25DEE, where DCP = digestible CP; DNDFap = digestible NDFap; DNFCap = digestible NFCap; and DEE = digestible EE.
Observations of ingestive behavior were conducted over 24 h on the 120th day of life. Animals were visually assessed every five minutes (Gary et al., 1970) by trained observers using digital stopwatches to record the time expended on each activity on an ethogram. Time expended grazing, ruminating, suckling, and engaging in other activities was recorded. Feeding time (grazing + feed consumption) and rumination time were calculated based on DM and NDF intake (min. kg-1 DM or NDF).
Grazing time was defined as the time expended selecting and prehending forage, including short intervals of movement associated with forage selection (Hancock, 1953). Rumination time included the processes of regurgitation, remastication, reinsalivation, and reswallowing. Suckling time was calculated by summing the observed periods of activity over 24h, while time allocated to other activities (rest, water intake, interactions, etc.) included all activities not described above.
The discretization of the time series was performed directly in the data collection spreadsheets by counting discrete bouts of feeding, rumination, and other activities. The average duration of each discrete bout was obtained by dividing the daily duration of each activity by the number of discrete bouts, according to Silva et al. (2006).
Total feeding time (TFT) and total chewing time (TCT) were obtained using the equations: TFT = GRA + TRO, where GRA = grazing time (min.) and TRO = feeding time at the trough (min.); and TCT = GRA + RUM + TRO, where GRA = grazing time (min.), RUM (min.) = rumination time, and TRO = feeding time at the trough (min.).
The number of rumination chews and the time expended ruminating each ruminal cud were recorded for each animal using a digital stopwatch. To obtain the average chewing and rumination times, three observations of ruminal cuds were taken between 09:00 and 12:00 and between 16:00 and 19:00, following Burger et al. (2000). The number of daily cuds was estimated by dividing the total rumination time by the average time expended ruminating each cud.
The biting rate of the animals in each group was estimated as the time required for an animal to take 20 bites (Hodgson, 1982). Bite and swallowing observations were recorded on six occasions during the day, as described by Baggio et al. (2009), with three evaluations in the morning and three in the afternoon. These data were also used to determine the number of bites per day, calculated as the product of biting rate and grazing time.
The number of cuds ruminated per day (CRD, n), cud chewing time (CCT, s), and number of chews per ruminated cud (CRC, n) were calculated using the following equations: CRD = RUM / CCT, where RUM = rumination time (s/day) and CCT = cud chewing time (s); and CRC = CRD × CRC. Feeding and rumination efficiency, expressed in kg h-1 for DM, NDF, NFC, and CP, was calculated by dividing the intake of each nutrient by total feeding time (feeding efficiency) or by rumination time (rumination efficiency).
The data were statistically analyzed using analysis of variance and the F-test at a 0.05 significance level in a completely randomized design, with the aid of the statistical software SAEG (System for Statistical Analysis, version 9.0).
Results and discussion
There was no effect (p>0.05) of concentrate supplementation during the middle third of gestation on the ingestive behavior of the calves (Table 2). Grazing time and rumination time did not differ (p>0.05), which is expected since both treatments had access to the same forage conditions. The high NDF content of the pasture is a limiting factor for intake, and both the quantity and quality of NDF can influence grazing and rumination times. NDF is a variable that directly affects ingestive behavior parameters (Van Soest, 1994; Mendonça et al., 2004). Age also affects grazing and rumination times; “[...] the intensity and constancy of the rumination process are defined two to three weeks after birth in animals with access to fibrous feed” (Rosenberger, 1993, p. 169). Given that the calves were four to five months old at the time of data collection, the observed values for grazing and rumination were not influenced by age.
Ingestive behavior (min day-1) of offspring from dams subjected to protein-mineral supplementation in the middle third of gestation.
The values obtained for grazing and rumination may also reflect the time expended suckling, since at this stage calves still do not obtain their full nutritional requirements from grazing. Although the animals were already considered functional ruminants, the presence of milk in the diet may still influence ingestive behavior.
Suckling time did not differ (p>0.05), with an average of 3.11% of the total time. This variable is influenced by factors such as nutritional requirements, dam size, and milk production. As no differences were observed for these factors between treatments, suckling time remained similar. Lopes et al. (2017), studying Nellore calves raised at foot and evaluated at approximately 120 days of age, reported an average suckling time of 3% of the total time.
The time expended on other activities was 744.375 and 691.429 min. day-1, respectively, with no difference (p>0.05). The pasture available during the evaluation period had characteristics of low-quality forage, due to high fiber and low crude protein content. Such conditions may reduce forage intake and consequently increase time expended on other activities.
Aldrighi et al. (2019) reported values of 746 and 735 min. day-1 for time expended on other activities when evaluating Nellore bulls and heifers, respectively, after weaning. The high values observed here may be attributed to the developmental stage of the animals, as during the pre-weaning period, socialization and learning dynamics still exert strong influence on daily activities.
Total chewing time also showed no effect (p>0.05). This result is expected because it is the sum of grazing and rumination times, which also showed no effect (p>0.05), as well as the absence of differences in NDF content in the animals’ diet, a factor known to affect the number and duration of chews.
Another factor that may influence the ingestive behavior of the evaluated animals is the development of their ingestive behavior itself. In young animals, much of this behavior is shaped by social models, such as the dam and other members of the group (Naeve et al., 2018).
The discrete bouts of behavioral variables showed no significant variation (p>0.05) (Table 3). This result may be associated with the fact that all animals evaluated belonged to the same category and, therefore, likely had similar body dimensions, ruminal capacity, and nutritional requirements. Protein supplementation of cows during the middle third of gestation was not sufficient to modify the number or duration of behavioral activity cycles in the offspring, likely due to similar dry matter intake and milk consumption. These findings support the hypothesis of an absence of anatomical and physiological differences in the gastrointestinal tract of the offspring.
According to Santana Júnior et al. (2013, p. 1346), "[...] time per bout corresponds to the quotient between the time expended on the activity and the number of bouts of the same activity”. Therefore, because no differences (p>0.05) were observed in either time expended or number of bouts (Table 3), no differences in time per bout were expected. Silva et al. (2015) reported a relationship between grazing and rumination times and NDF and ADF intake, attributed to changes in forage passage rate, with NDF acting as either a limiting or stimulating factor. Under conditions of high dietary NDF concentration, a greater number of meals per animal is typically observed, directly affecting grazing and rumination times due to the prehension of smaller forage particles.
Among bite-related variables, biting rate, bite mass, and number of bites per day were affected (p<0.05) (Table 3). Offspring of supplemented cows exhibited a lower pasture intake rate (biting rate) and greater bite mass, which could indicate improved selectivity; however, this effect was not seen in the present study. During the data collection period, forage quality had already declined, and the observed differences may be associated with the animals’ ability to more effectively select ingested material during grazing. Additionally, anatomical differences in mouth size may influence biting rate and number of bites per day, as animals with wider mouths can capture more forage per bite and may reach ruminal fill limits more rapidly.
Rumination-related variables were not influenced (p>0.05) (Table 3). One of the primary functions of rumination is to reduce fibrous particle size, and because no differences were observed in the calves’ diets, variation among rumination parameters was unlikely. Silva et al. (2015) also reported a direct relationship between rumination variables and neutral detergent fiber content in the diet.
Conclusion
Protein concentrate supplementation during the middle third of gestation did not influence the ingestive behavior of the offspring, except for bite-related variables.
Data availability
The data in this article are part of a doctoral thesis entitled “Fetal Nutrition in Beef Calf Production” which is available at https://repositorio.ufpi.br/xmlui/handle/123456789/3155
References
-
Abuelot, A.. (2020). Symposium review: late-gestation maternal factors affecting the health and development of dairy calves. Jounal of Dairy Scienci, 103(4), 3882-3893. https://doi.org/10.3168/jds.2019-17278
» https://doi.org/https://doi.org/10.3168/jds.2019-17278 -
Aldrighi, J., Branco, R. H., Cyrillo, J. S. G., Magnani, E., Nascimento, C. F., Bonilha, S. F. M. & Mercadante, M. E. Z.. (2019). Ingestive behavior and temperament of Nellore cattle classified for residual feed intake. Semina: Ciências Agrárias, 40(1), 457-468. https://doi.org/10.5433/1679-0359.2019v40n1p457
» https://doi.org/https://doi.org/10.5433/1679-0359.2019v40n1p457 -
Baggio, C., Carvalho, P. C. F., Silva, J. L. S., Anghinoni, I., Lopes, M. L. T. & Thurow, J. M.. (2009). Padrões de deslocamento e captura de forragem por novilhos em pastagem de azevémanual e aveia-preta manejada sob diferentes alturas em sistema de integração lavourapecuária. Revista Brasileira de Zootecnia, 38(2), 215-222. https://doi.org/10.1590/S1516-35982009000200001
» https://doi.org/https://doi.org/10.1590/S1516-35982009000200001 -
Burger, P. J., Pereira, J. C., Queiroz, A. C., Coelho da Silva, J. F., Valadares Filho, S. C., Cecon, P. R. & Casali, A. D. P.. (2000). Consumo e digestibilidades aparentes total e parcial em bezerros holandeses alimentados com dietas contendo diferentes níveis de concentrado. Revista Brasileira de Zootecnia, 29(1), 206-214. https://doi.org/10.1590/S1516-35982000000100028
» https://doi.org/https://doi.org/10.1590/S1516-35982000000100028 -
Campbell, A. G.. (1966). Grazed pastures parameters. I. Pasture dry matter production and availability in a stocking rate and grazing management experiment with dairy cows. The Journal of Agriculture Science, 67(2), 199-210. https://doi.org/10.1017/S0021859600068283
» https://doi.org/https://doi.org/10.1017/S0021859600068283 -
Caton, J. S., Crouse, M. S., Reynolds, L. P., Neville, T. L., Dahlen, C. R., Ward, A. K. & Swanson, K. C.. (2019). Maternal nutrition and programming of offspring energy requirements. Translational Animal Science, 3(3), 976-990. https://doi.org/10.1093/tas/txy127
» https://doi.org/https://doi.org/10.1093/tas/txy127 -
Costa, T., Du, M., Nascimento, K., Galvão, M., Meneses, J., Schultz, E., Gionbelli, M. & Duarte, M.. (2021). Desenvolvimento do músculo esquelético em bovinos de corte pós-natal resultante da restrição proteica materna durante a metade da gestação. Animals, 11(3), 860. https://doi.org/10.3390/ani11030860
» https://doi.org/https://doi.org/10.3390/ani11030860 -
Custodio, S. A. S., Tomaz, M. P. P., Silva, D. A. L., Goulart, R. O., Dias, K. M. & Carvalho, E. R.. (2017). Feeding behavior of beef cattle fed different forages and housed in individual or collective pens. Journal of Animal Behaviour and Biometeorology, 5(1), 20-28. https://doi.org/10.14269/2318-1265/jabb.v5n1p20-28
» https://doi.org/https://doi.org/10.14269/2318-1265/jabb.v5n1p20-28 -
Deniz, N. N., Chelotti, J. O., Galli, J. R., Planisich, A. M., Larripa, M. J., Rufiner, H. L. & Giovanini, L. L.. (2017). Embedded system for real-time monitoring of foraging behavior of grazing cattle using acoustic signals. Computers and Electronics in Agriculture, 138(1), 167-174. https://doi.org/10.1016/j.compag.2017.04.024
» https://doi.org/https://doi.org/10.1016/j.compag.2017.04.024 - Detmann, E., Souza, M. A., Queiroz, A. C., Berchielli, T. T., Saliba, E. O. E., Cabral, L. S., Pina, D. S., Ladeira, M. M. & Azevedo, J. A. G. (2012). Métodos para análise de alimentos. Universidade Federal de Viçosa.
-
Dias-Silva, T. P. & Abdalla Filho, A. L.. (2021). Sheep and goat feeding behavior profile in grazing systems. Acta Scientiarum. Animal Sciences, 43(1), e51265. https://doi.org/10.4025/actascianimsci.v43i1.51265
» https://doi.org/https://doi.org/10.4025/actascianimsci.v43i1.51265 -
Fernandes, T. A., Cerdótes, L., Vaz, R. Z., Restle, J. & Ferreira, O. G. L.. (2020). Relationship between heterosis, weight gain, and body measurements of Nellore and Charolais calves. Pesquisa Agropecuária Brasileira, 55(1), e01821. https://doi.org/10.1590/S1678-3921.pab2020.v55.01821
» https://doi.org/https://doi.org/10.1590/S1678-3921.pab2020.v55.01821 -
Gary, L. A., Sherritt, G. W. & Hale, E. B.. (1970). Behavior of Charolais cattle on pasture. Journal of Animal Science, 30(2), 203-206. https://doi.org/10.2527/jas1970.302203x
» https://doi.org/https://doi.org/10.2527/jas1970.302203x -
Ghotbaldini, H., Mohammadabadi, M., Nezamabadi-Pour, H., Babenko, O. I, Bushtruk, M. V. & Tkachenko, S. V.. (2019). Predição do valor genético do peso corporal aos 6 meses de idade usando redes neurais artificiais na raça de ovinos Kermani. Acta Scientiarum. Animal Sciences, 41(1), e45282. https://doi.org/10.4025/actascianimsci.v41i1.45282
» https://doi.org/https://doi.org/10.4025/actascianimsci.v41i1.45282 -
Hall, M. B.. (2003). Challenges with nonfiber carbohydrate methods. Journal of Animal Science, 81(12), 3226-3232. https://doi.org/10.2527/2003.81123226x
» https://doi.org/https://doi.org/10.2527/2003.81123226x - Hancock, J.. (1953). Grazing behaviour of cattle. Animal Breeding Abstract, 21(1), 1-13.
- Hodgson, J. (1982). Influence of sward characteristics on diet selection and herbage intake by the grazing animal. In J. B. Hacker (Ed.), Nutritional limits to animal production from pasture. (pp. 153-166). CAB.
- Johnson, A. D. (1978). Sample preparation and chemical analysis of vegetation. In L. t´Mannetje (Ed.), Measurement of grassland vegetation and animal production. (pp. 96-102). Commonwealth Agricultural Bureaux.
-
Licitra, G., Hernandez, T. M. & Van Soest, P. J.. (1996). Standardization of procedures for nitrogen fractionation of ruminant feeds. Animal Feed Science and Technology, 57(4), 347-358. https://doi.org/10.1016/0377-8401(95)00837-3
» https://doi.org/https://doi.org/10.1016/0377-8401(95)00837-3 -
Lopes, S. A., Paulino, M. F., Detmann, E., Valente, E. E. L., Renno, L. N., Valadares, R. F. D., Cardenas, J. E. G., Almeida, D. M., Moura, F. H. & Oliveira, C. A. S.. (2017). Evaluation of supplementation plans for suckling beef calves managed on tropical pasture. Semina: Ciências Agrárias, 38(2), 1027-1040. https://doi.org/10.5433/1679-0359.2017v38n2p1027
» https://doi.org/https://doi.org/10.5433/1679-0359.2017v38n2p1027 -
Mendonça, S. S., Campos, J. M. S., Valadares Filho, S. C., Valadares, R. F. D., Soares, C. A., Lana, R. P., Queiroz, A. C., Assis, A. J. & Pereira, M. L. A.. (2004). Comportamento ingestivo de vacas leiteiras alimentadas com dietas à base de cana-de-acúcar ou silagem de milho. Revista Brasileira de Zootecnia, 33(3), 723-728. https://doi.org/10.1590/S1516-35982004000300021
» https://doi.org/https://doi.org/10.1590/S1516-35982004000300021 -
Naeve, H. W., Weary, D. M. & Keyserlingk, M. A. G.. (2018). Review: individual variability in feeding behaviour of domesticated ruminants. Animal, 12(suppl. 2), s419-s430. https://doi.org/10.1017/S1751731118001325
» https://doi.org/https://doi.org/10.1017/S1751731118001325 -
Prohmann, P. E. F., Branco, A. F., Jobim, C. C., Cecato, U., Paris, W. & Mauro, J. F.. (2004). Suplementação de bovinos em pastagem de Coastcross (Cynodon dactylon (L.) Pers) no verão. Revista Brasileira de Zootecnia, 33(3), 792-800. https://doi.org/10.1590/S1516-35982004000300028
» https://doi.org/https://doi.org/10.1590/S1516-35982004000300028 -
Pereira, K. C. B., Carvalho, C. C. S., Ruas, J. R. M., Menezes, G. C. C., Castro, A. L. O. & Costa, M. D.. (2018). Effect of the climatic environment on ingestive behavior of F1 Holstein x Zebu cows. Revista Brasileira de Saúde e Produção Animal, 19(2), 207-215. https://doi.org/10.1590/S1519-99402018000200006
» https://doi.org/https://doi.org/10.1590/S1519-99402018000200006 -
Rodrigues, L. M., Schoonmaker, J. P., Resende, F. D., Siqueira, G. R., Neto, O. R. M., Gionbelli, M. P., Gionbelli, T. R. S. & Ladeira, M. M.. (2021). Efeitos da suplementação proteica no desempenho reprodutivo, crescimento, miogênese, lipogênese e desenvolvimento intestinal da progênie de vacas Nelore. Animal Production Science, 61(4), 371-380. https://doi.org/10.1071/AN20498
» https://doi.org/https://doi.org/10.1071/AN20498 - Rosenberger, G. (1993). Exame clínico dos bovinos. Guanabara Koogan Editora.
-
Sampaio, A. F., Mendes, F. B. L., Silva, R. R., Lins, T. O. & Santana Júnior, H. A.. (2025). Correlations between intake and ingestive behavior of supplemented pasture-finished steers. Acta Scientirum. Animal Science, 47(1), 71536. https://doi.org/10.4025/actascianimsci.v47i1.71536
» https://doi.org/https://doi.org/10.4025/actascianimsci.v47i1.71536 -
Santana Júnior, H. A., Figueiredo, M. P., Cardoso, E. O., Mendes, F. B. L., Abreu Filho, G., Pinheiro, A. A., Lisboa, M. M., Luz, Y. S., Viana, P. T., Ferreira, A. H. C. & Rech, C. L. S.. (2013). Glicerina bruta na dieta de vacas lactantes mantidas em pastagem tropical: Comportamento ingestivo. Semina. Ciências Agrárias, 34(3), 1339-1352. https://doi.org/10.5433/1679-0359.2013v34n3p1339
» https://doi.org/https://doi.org/10.5433/1679-0359.2013v34n3p1339 -
Santos, M. C., Silva, R. R., Silva, F. F., Oliveira, A. B., Santos, L. V., Paixão, T. R., Silva, A. P. G., Silva, J W. D., Barbosa, R. P. & Costa, G. D.. (2020). Nutrient intake and ingestive behavior of feedlot steers fed with licuri cake. Tropical Animal Health and Production, 52(1), 1803-1809. https://doi.org/10.1007/s11250-019-02189-2
» https://doi.org/https://doi.org/10.1007/s11250-019-02189-2 - Silva, R. R., Silva, F. F., Prado, I. N., Carvalho, G. G. P., Franco, I. L., Almeida, V. S., Cardoso, C. P. & Ribeiro, M. H. S.. (2006). Comportamento ingestivo de bovinos. Aspectos metodológicos. Archivos de Zootecnia, 55(211), 293-296.
-
Silva, R. R., Oliveira, A. C., Carvalho, G. G. P., Silva, F. F., Mendes, F. B. L., Almeida, V. V. S., Rodrigues, L. B. O., Pinheiro, A. A., Silva, A. P. G., Silva, J. W. D. & Lisboa, M. M.. (2015). Correlation between intake and feeding behavior of Holstein calves fed diets supplemented with pellets and mash. American Journal of Experimental Agriculture, 7(6), 382-388. https://doi.org/10.9734/AJEA/2015/13891
» https://doi.org/https://doi.org/10.9734/AJEA/2015/13891 - Valadares Filho, S. C., Costa E Silva, L. F., Gionbelli, M. P., Rotta, P. P., Marcondes, M. I., Chizzotti, M. L. & Prados, L. F.. (2016). Exigências nutricionais de zebuínos puros e cruzados BR-CORTE. Universidade Federal de Viçosa, DZO.
- Van Soest, P. J.. (1994). Nutritional ecology of the ruminant. Cornell University, NY.
Edited by
-
Associate Editor in charge:
Leandro Dalcin Castilha
