Heat stress on the feed consumption, biochemical indicators, production and milk quality of holstein and jersey cowsABSTRACT:
This research compared dry matter intake, milk yield, milk composition, and physiological and biochemical parameters between holstein and jersey cows under heat stress. Holstein (n=8) and Jersey (n=8) cows were allocated into two treatment groups: VA, with cooling, and SVA, with no cooling. The experiment included 14 days of adaptation (all the cows were cooled) and 5 days of evaluation (only the VA cows were cooled). Dry matter intake and milk production were measured daily. On Day 0 of the adaptation period and on Days 1, 3 and 5 of the evaluation period, milk samples were collected for composition, physicochemical and somatic cell analysis; blood was collected for analysis of the contents of total proteins, albumin, urea, creatinine, glucose, and beta-hydroxybutyrate. The physiological parameters measured were respiratory rate, surface temperature, rectal temperature and ruminal movements. The experimental design was a 2 × 3 factorial, with two treatments and three days. The data were subjected to ANOVA and tested for normality of the residuals. For dry matter intake, there was a treatment*day interaction, and the milk yield and composition of the treatments were similar. Only the protein content was greater in the VA treatment group than in the SVA group. The milk from SVA cows had greater resistance to ethanol than that from VA cows. The freezing point was greater in the VA treatment group. The concentration of beta-hydroxybutyrate was greater in the VA treatment group. A short heat stress period did not immediately affect production, but it did affect the composition and physicochemical properties of milk. The active cooling of cows with ventilation and sprinkling influences the amount of heat produced and retained, impacting the physiological parameters, blood metabolites, composition, and physicochemical properties of milk.
Key words:
heat; thermotolerance; physicochemical properties of milk
RESUMO:
Este trabalho teve como objetivo comparar o consumo de matéria seca, produção de leite, composição do leite e parâmetros fisiológicos e bioquímicos entre vacas Holandesas e Jersey sob estresse térmico. Vacas Holandesas (n=8) e Jersey (n=8) foram alocadas em dois grupos de tratamento: VA, com resfriamento, e SVA, sem resfriamento. O experimento incluiu 14 dias de adaptação (todas as vacas foram resfriadas) e cinco dias de avaliação (apenas as vacas VA foram resfriadas). O consumo de matéria seca e a produção de leite foram medidos diariamente. No Dia 0 do período de adaptação e nos Dias 1, 3 e 5 do período de avaliação, foram coletadas amostras de leite para análise de composição, físico-química e células somáticas; foi coletado sangue para análise do conteúdo de proteínas totais, albumina, uréia, creatinina, glicose e beta-hidroxibutirato. Os parâmetros fisiológicos medidos foram frequência respiratória, temperatura superficial, temperatura retal e movimentos ruminais. O delineamento experimental foi fatorial 2 × 3, com dois tratamentos e três dias. Os dados foram submetidos à ANOVA e testados quanto à normalidade dos resíduos. Para o consumo de matéria seca houve interação tratamento*dia e a produção e composição do leite foram semelhantes. Apenas o conteúdo proteico foi maior no grupo de tratamento VA do que no grupo SVA. O leite das vacas SVA apresentou maior resistência ao etanol do que o das vacas VA. O ponto de congelamento foi maior no grupo de tratamento VA. A concentração de beta-hidroxibutirato foi maior no grupo de tratamento VA. Um curto período de estresse térmico não afetou imediatamente a produção, mas afetou a composição e as propriedades físico-químicas do leite. O resfriamento ativo das vacas com ventilação e aspersão influencia a quantidade de calor produzido e retido, impactando nos parâmetros fisiológicos, metabólitos sanguíneos, composição e propriedades físico-químicas do leite.
Palavras-chave:
calor; termotolerância; propriedades físico-químicas do leite
INTRODUCTION
High environmental temperatures affect productivity and animal welfare, causing considerable economic losses in global livestock farming. Heat stress can be defined as a physiological condition in which the core body temperature of a given species exceeds its thermoneutral range, causing an accumulation of heat, which can come from the organism itself or from the environment (BERNABUCCI et al., 2010). Thermal balance can be affected by different climatic elements (ambient temperature, relative humidity, solar radiation, air movement and precipitation), animal factors (metabolic rate, sweating rate), and animal thermoregulatory mechanisms (COLLIER et al., 2008).
Dairy cows under heat stress may experience reduced milk production; reduced dry matter intake (DMI); physiological and behavioral changes to dissipate heat (ISLAM et al., 2021); and adverse effects on reproduction, immunity and homeostatic balance, increasing the susceptibility of high-yielding cows to heat stress (HU et al., 2016; KRISTENSEN et al., 2004). The most common dairy breeds in the global livestock industry include the Holstein breed, which is characterized by high milk production, and the Jersey breed, which is widely used to produce milk with high fat and protein content and is characterized by better fertility and greater longevity than other cows (MCGUFFEY & SHIRLEY, 2011). Although, not entirely clear, the mechanisms related to reduced milk production may be multifactorial. In addition to the reduction in DMI, it may be related to changes in metabolism, activation of the immune system, inflammation, and altered mammary gland function and development (TAO et al., 2020). At the cellular level, the heat shock response begins with activation of heat shock transcription Factor 1 (HSF1), increased expression of heat shock proteins (HSPs), decreased expression and synthesis of other proteins, increased oxidation of glucose and amino acids, decreased metabolism of fatty acids, and activation of the immune system through extracellular secretion of HSPs (COLLIER, 2008).
Despite major advances in ambient and cooling systems, hot weather still represents a major challenge for global dairy production. The provision of natural or artificial shade, ventilation, and water spraying, alone or in combination, are ways to mitigate the effects of heat stress. In a humid subtropical climate, the combined use of shade with ventilation and sprinkler cycles is common on dairy farms. CHEN et al. (2016) tested the use of ventilation combined with different water flow rates in a sprinkler system to mitigate heat stress in cows. They observed that providing continuous ventilation and water spray cycles (3 minutes with the sprinkler system on and 9 minutes off, 24 hours/day) was effective in reducing cows’ body temperature by 0.3 to 0.9 °C. They also observed that a water flow of 1.3 L/min in the sprinkler system has the same effect as 4.9 L/min, thus showing possibilities for the rational use of water, a scarce natural resource in many regions of the world. Thus, this study observed the effect of heat stress on the consumption, production and quality of milk and on the biochemical and physiological indicators of Holstein and Jersey cows.
MATERIALS AND METHODS
The experiment was conducted on a farm in the city of Itapiranga, SC, Brazil (27° 7’2.12”S, 53°47’42.57”W), with a Cfa climate (humid subtropical), according to the Köppen-Geiger classification (DUBREUIL et al., 2018). All procedures involving the cows in the experiment were approved by the Ethics and Animal Experimentation Committee of the State University of Santa Catarina under protocol number 6172220518.
Animals and accommodation
Sixteen cows (n = 8) Holstein and (n = 8) Jersey were housed in a compost-bedded pack barn and divided into two groups: one group with cooling by ventilation (VA) in the entire barn area and sprinkling in the trough feedbunk line and one group without cooling (SVA). The barn was 40 m × 9 m in size and offered an area of 11.62 m2 per animal. The cows were divided into homogeneous groups according to live weight, parity, days in milk (DIM), body condition score (BCS) and milk production. There were 4 Holstein cows and 4 Jersey cows in the VA group (BW= 473.8 ± 86.4 kg; parity = 2.43 ± 1.3; DIM = 130.9 ± 94; BCS = 3.02 ± 0.2 and milk = 22 ± 6 kg/day) and the SVA group (BW= 477.7 ± 65.7 kg; parity = 2.37 ± 1.3; DIM = 123.8 ± 83.4; BCS = 3.00 ± 0.3 and milk = 21.7 ± 4.5 kg/day).
The experiment lasted 19 days, including an adaptation period (PAd) of 14 days and an evaluation period of 5 days (PEv) to assess the effects of heat stress. In the PAd period, the cows were adapted to the management and batches, and all animals were cooled using fans throughout the barn area and sprinklers in the feeding pen line (GRANT et al., 2015; CHEN et al., 2016). The cooling system for the cows included fans (diameter = 2 m), which ensured an average wind speed of 3.72 m/s at the cows. The sprinkler system was installed above the feedbunk line, with sprinkler nozzles at 0.9 m intervals providing water cooling for each cow at a flow rate of 0.75 l/min during feeding. The ventilation and sprinkler system were automatically controlled and activated when the ambient temperature was 24 °C or higher. Ventilation was continuous, and the sprinkler system was operated in intermittent cycles of 2 minutes of spraying and 15 minutes of system shutdown. The last day of the PAd period was considered Day 0, and all cows had access to ventilation and spraying. From Day 1 to Day 5, only the cows in the VA group continued to have access to ventilation and spraying. Blood and milk samples were collected on Days 0, 1, 3 and 5. The two groups of cows in the trial were separated from each other and from the rest of the animals in the barn by electric fences.
Environmental conditions of confinement
The temperature and humidity conditions in the barn were determined using a data logger and measured at 15-minute intervals. The temperature and humidity index (THI) was calculated from the temperature and humidity data using the following formula: THI = (1.8 × T + 32) - [(0.55-0.0055 × RH) × (1.8 × T - 26)], where T = air temperature (°C) and RH = relative humidity (%) (NRC, 1971).
Body weight (BW) and body condition score (BCS)
Body weight was determined at the beginning of the adaptation period using a digital scale (Filizola Balanças Industriais, São Paulo, Brazil). The BCS was determined at the beginning of the adaptation period according to the method of FERGUSON et al. (1994).
Respiratory rate, surface temperature, rectal temperature and rumen movements
The respiratory rate (RR) was measured by visually counting the respiratory movements of the flank for 15 seconds and multiplying this value by four to obtain the rate per minute. The surface temperature (ST) of the cows was determined with an infrared thermometer at a distance of 1 m from the animal at five points on the body (head, withers, groin, udder, and tibia), with the final value being the average of the five points per animal. Rectal temperature (RT) was determined using a digital clinical thermometer inserted into the rectum (FERREIRA et al., 2006). Ruminal movements (RMs) were determined visually by counting the movements of the left flank for 2 minutes (PAUDYAL, 2021; (SCHIRMANN et al., 2009). The RR, ST, RT and RM of the cows were determined twice daily at 10 am and 7 pm on Days 0, 1, 3 and 5.
Dry matter consumption and food sample collection
The trial diet was formulated to meet 100% of the nutrient requirements according to the NRC (2001) as a total mixed ration (TMR). The components of the TMR on a dry matter basis were as follows: corn silage, 48.63%; Tifton-85 hay, 11.89%; commercial concentrate, 30.25%; soybean meal, 7.78%; and mineral supplement, 1.45%. The bromatological parameters of the TMR were as follows: PB, 18.21%; NDF, 31.13%; FDA, 21.84%; EE, 3.79%; MM, 8.28%; and CNF, 39.73%. The net lactation energy of the ration was 1.55 Mcal/kg DM.
The feed was provided in individual troughs for each cow at four times: 08:00, 12:00, 16:00, and 19:00. The cows were allowed to access the feed for 1 hour and 30 minutes at each time point. Fresh feed was offered twice: at 08:00 and 16:00. The amount of feed offered to each animal was adjusted daily to 5 and 10% of the leftovers. The leftover feed was collected daily after the last feeding period for weighing. On Days 0, 1, 3 and 5, samples of leftover feed and forage were taken and analyzed as described by HAUSER et al. (2023).
Collection and analysis of milk samples
The cows were milked twice a day, at 07:00 and 17:30. Milk production was measured daily during the adaptation and collection periods using WAIKATO® milk multimeters. On Days 0, 1, 3, and 5, milk samples were taken from each cow from the morning and afternoon milkings and kept refrigerated (3 to 8 °C). An aliquot of milk was combined with bronopol preservative and sent to the laboratory of the Association of Holstein Cattle Breeders of Paraná (APCBRH) in Curitiba (PR) for analysis of fat, protein, lactose, total solid, and milk urea nitrogen (NUL) contents using the infrared method (Bentley Combisystem, Bentley Instruments Inc., USA). The somatic cell count (SCC) was determined using flow cytometry (Delta Combiscope, Advanced Instruments Inc., USA). The somatic cell score (SCS) was calculated using the following formula: SCS = log 2 (SCC/100) + 3. The milk samples from each cow were also analyzed for ethanol stability, titratable acidity, and freezing point degree as described by HAUSER et al. (2023).
Collection and analysis of blood samples
On Days 0, 1, 3 and 5, blood samples were taken from the coccygeal vessels after feeding (two 10-mL vacutainer tubes with lytic heparin (BD, New Jersey, USA), two 4-mL vacutainer tubes containing K2EDTA (potassium ethylenediaminetetraacetate) (BD, New Jersey, USA) and two 10-mL tubes containing clot activator for serum collection (BD, New Jersey, USA)) using a 21-G needle. After collection, the blood was centrifuged at 1.328 g for 10 minutes. The resulting plasma and serum samples were placed in 2 mL plastic tubes and frozen at -20 °C until analysis. Albumin, urea, creatinine, beta-hydroxybutyrate (BHB), and glucose concentrations were determined according to the methods described by PELIZZA et al. (2019).
Data analysis
The data were analyzed by ANOVA using the MIXED procedure and previously tested for normality of the residuals with the Shapiro‒Wilk test using the SAS® statistical package. (SAS, 2017). The last day of the adaptation period was considered Day 0, and the collected data were used as covariates in the statistical model. The effects of treatment, treatment days, treatment, and day interaction were included in the statistical model, and the value for each dependent variable observed on Day 0 included as a covariate. Mean values were considered different if P ≤ 0.05.
RESULTS
The values related to the temperature and humidity index (THI) are shown in figure 1. For CMS, there was an interaction effect between treatment and day (P = 0.0001). Milk production was similar between treatments (P = 0.873), with an effect of day (P = 0.017). The milk compositions of the VA and SVA treatment groups were similar, differing only in protein content, which was greater in the VA milk than in the SVA milk (P = 0.001). There was an effect of sampling day on SCS (P = 0.015). The full results are shown in table 1 and figure 2 (A, B, C and D).
Temperature and humidity index (THI) determined during the evaluation period in the VA (with cooling) and SVA (without cooling) treatment environments.
Least squares mean, standard error of the mean (SEM) and P value for dry matter intake (DMI), production, milk composition, somatic cell score (SCS) and milk urea nitrogen (MUN) evaluated in cows from the VA (with cooling) and SVA (without cooling) treatment (Treat.).
(A) Dry matter intake (DMI), (B) milk production, (C) fat content and (D) protein content of cows in the VA (with cooling) and SVA (without cooling) treatment groups as a function of days.
The mean milk resistance to ethanol test results were greater in the SVA treatment group than in the VA group (P = 0.005). There was an interaction effect between treatment and day on the titratable acidity of milk samples (P = 0.003). There was an effect of sampling day only on the milk pH (P < 0.0001). The freezing point was greater in the VA treatment group than in the SVA treatment group (P = 0.006), and sampling day had an effect on freezing point (<0.0001). The detailed results are shown in table 2.
Least squares mean, standard error of the mean (SEM), and P value for the physicochemical properties of milk evaluated in cows from the VA (with cooling) and SVA (without cooling) treatment groups.
There was an effect of sampling day on RR in the morning (P < 0.0001), ST in the morning and afternoon (P < 0.0001) and RM in the afternoon (P = 0.042). The SVA treatment group had higher RM values than did the VA treatment group in the morning (P = 0.032). There was an interaction effect between treatment and sampling day for RT in the morning (P = 0.0002), RR in the afternoon (P < 0.0001), ST in the afternoon (P < 0.0001), and RT in the afternoon (P < 0.0001). The detailed results are shown in table 3.
Among the biochemical parameters evaluated, the treatments differed in the concentration of beta-hydroxybutyrate, which was greater in the VA group (P < 0.0001). There was an effect of day on total protein (P = 0.0004), globulin (P = 0.028), urea (P < 0.0001), creatinine (P < 0.0001), and BHB (P < 0.0001). The detailed results are shown in table 4.
Least squares mean, standard error of the mean (SEM) and P value for the biochemical parameters evaluated in cows from the VA (ventilation and sprinkler) and SVA (without ventilation and sprinkler) treatments (treat.).
DISCUSSION
The THI is used to estimate the cooling requirements of dairy cows, and if this value exceeds 68, a reduction in milk production can be observed (TAO et al., 2020). The THI determined on the evaluation days indicates conditions outside the thermoneutral zone for dairy cows. The most recognized effect of increasing body temperature is the adaptive depression of metabolic rate associated with reduced appetite (SILANIKOVE, 2000; RENQUIST, 2019). Heat stress leads to a decrease in DMI, milk production and milk components (WHEELOCK et al., 2010; RHOADS et al., 2009), with the effects being more pronounced in cows in the middle and end of the lactation stage than in cows at the beginning of the lactation stage (TAO et al., 2020). The similar DMI between the treatments in our study may be related to the short period and the lactation stage of the cows in the experiment.
The effects of heat stress on the composition of milk are diverse. Normally, along with a reduction in production, there is a reduction in milk components. However, several studies have shown different results for milk fat and protein content, which may be greater, lower, or remain unchanged in summer (HECK et al., 2009; SMITH et al., 2013; BERNABUCCI et al., 2015). The results showed that a short period of heat stress mainly affected the protein content of the milk. An alteration in the secretory function of the mammary gland may be the main reason for these decreases, which could be an adaptive response to maintain cellular homeostasis. Mammary epithelial cells can be directly affected by heat stress, and this stimulus reaches the cytoplasm within a few minutes, triggering the heat shock response via the synthesis of heat shock proteins (HU et al., 2016).
Heat stress influenced the physicochemical properties of the milk. The milk from cows in the SVA treatment group showed greater stability in the ethanol test and a lower freezing point than did the milk from cows in the VA treatment group. The lower stability of the milk in the ethanol test is related to individual variations observed in some cows or a lower concentration of alpha-lactalbumin (α-LA) in the milk (FAGNANI et al., 2018), which was not analyzed in this trial. The freezing point of milk is relatively constant and reflects the osmotic balance between blood and milk (HENNO et al., 2008). The freezing point test can be used to detect the intentional addition of water to milk. Lactose and dissolved ions are responsible for approximately 80% of the decrease in the freezing point, while other substances such as urea, short-chain fatty acids and CO2 are responsible for approximately 20% (TÖPEL, 2016). The results suggested that variations in milk components (not all of which were analyzed) may have occurred or may be due to the degree of hydration of the cows.
Heat stress is associated with changes in the concentration of blood metabolites and systemic metabolic reactions (TAO et al., 2020) (MARINS et al., 2019). MARINS et al. (2019) reported that noncooled cows under heat stress had lower concentrations of glucose, beta-hydroxybutyrate (BHB), nonesterified fatty acids (NEFAs), and triglycerides than cooled cows, resulting in a decrease in DMI and lower nutrient requirements for milk synthesis. HECK et al. (2009) observed lower levels of fatty acids from de novo synthesis and higher levels of preformed fatty acids in milk produced in summer than in milk produced in winter. Acetate and BHB are precursors of the de novo synthesis of fatty acids and are formed in the rumen from polysaccharides in the diet (SAMKOVÁ et al., 2012). In our study, cooled cows (VA group) had higher BHB concentrations than noncooled cows (SVA group), which could be related to the ability of cooled cows to metabolize body fat to sustain milk production (RHOADS et al., 2009).
CONCLUSION
Active cooling through ventilation and spraying of Holstein and Jersey cows influences the amount of heat produced and retained, which does not affect milk production in the short term but affects physiological parameters, blood metabolites, components, and physicochemical properties of the milk.
ACKNOWLEDGMENTS
We would like to thank SINDILEITE/SC Sindicato das Indústrias de Laticínios e Produtos Derivados do Estado de Santa Catarina (SINDILEITE/SC) and Fundação de Apoio à Pesquisa do Estado de Santa Catarina (FAPESC) for the financial resources provided to fund this project. We also acknowledge Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Finance Code 001, for granting a doctoral scholarship, and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq).
REFERENCES
-
BERNABUCCI, U. et al. Effect of summer season on milk protein fractions in Holstein cows. Journal of Dairy Science, v.98, n.3, p.1815-1827, 2015. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0022030214008984 >. Accessed: Apr. 30, 2024. doi: 10.3168/jds.2014-8788.
» https://doi.org/10.3168/jds.2014-8788.» https://www.sciencedirect.com/science/article/pii/S0022030214008984 -
BERNABUCCI, U. et al. Metabolic and hormonal acclimation to heat stress in domesticated ruminants. Animal, v.4, n.7, p.1167-1183, 2010. Available from: <Available from: https://pubmed.ncbi.nlm.nih.gov/22444615/ >. Accessed: Apr. 30, 2024. doi: 10.1017/S175173111000090X.
» https://doi.org/10.1017/S175173111000090X.» https://pubmed.ncbi.nlm.nih.gov/22444615/ -
CHEN, J. M. et al. Cooling cows efficiently with water spray: Behavioral, physiological, and production responses to sprinklers at the feed bunk. Journal of Dairy Science, v.99, n.6, p.4607-4618, 2016. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0022030216301503 >. Accessed: Apr. 30, 2024. doi: 10.3168/jds.2015-10714.
» https://doi.org/10.3168/jds.2015-10714.» https://www.sciencedirect.com/science/article/pii/S0022030216301503 -
COLLIER, R. J. et al. Genes Involved in the Bovine Heat Stress Response. Journal of Dairy Science, v.91, n.2, p.445-454, 2008. Available from: <Available from: http://linkinghub.elsevier.com/retrieve/pii/S0022030208713869 >. Accessed: Apr. 30, 2024. doi: 10.3168/jds.2007-054.
» https://doi.org/10.3168/jds.2007-054.» http://linkinghub.elsevier.com/retrieve/pii/S0022030208713869 -
DUBREUIL, V. et al. Os tipos de climas anuais no Brasil: uma aplicação da classificação de Köppen de 1961 a 2015. Confins, v.37, n.37, p.1-20, 24 set. 2018. Available from: <Available from: http://journals.openedition.org/confins/15738 >. Accessed: Apr. 30, 2024. doi: 10.4000/confins.15738
» https://doi.org/10.4000/confins.15738» http://journals.openedition.org/confins/15738 -
FAGNANI, R. et al. Field findings about milk ethanol stability: a first report of interrelationship between α-lactalbumin and lactose. Journal of the Science of Food and Agriculture, v.98, n.7, p.2787-2792, 2018. Available from: <Available from: https://onlinelibrary.wiley.com/doi/abs/10.1002/jsfa.8775 >. Accessed: Apr. 30, 2024. doi: 10.1002/jsfa.8775.
» https://doi.org/10.1002/jsfa.8775.» https://onlinelibrary.wiley.com/doi/abs/10.1002/jsfa.8775 -
FERGUSON, J. D. et al. Principal Descriptors of Body Condition Score in Holstein Cows. Journal of Dairy Science, v.77, n.9, p.2695-2703, 1994. Available from: <Available from: https://pubmed.ncbi.nlm.nih.gov/7814740/ >. Accessed: Apr. 30, 2024. doi: 0.3168/jds.S0022-0302(94)77212-X.
» https://doi.org/0.3168/jds.S0022-0302(94)77212-X.» https://pubmed.ncbi.nlm.nih.gov/7814740/ -
FERREIRA, F. et al. Parâmetros fisiológicos de bovinos cruzados submetidos ao estresse calórico. Arquivo Brasileiro de Medicina Veterinaria e Zootecnia, v.58, n.5, p.732-738, 2006. Available from: <Available from: https://www.scielo.br/j/abmvz/a/kXyHJkDDvBXHGHHMDWmT77Q/abstract/?lang=pt >. Accessed: Apr. 30, 2024. doi: 10.1590/S0102-09352006000500005.
» https://doi.org/10.1590/S0102-09352006000500005.» https://www.scielo.br/j/abmvz/a/kXyHJkDDvBXHGHHMDWmT77Q/abstract/?lang=pt -
GRANT, R. J. et al. Time required for adaptation of behavior, feed intake, and dietary digestibility in cattle. J. Dairy Sci., v.98, Suppl., p.312, 2015. Available from: <Available from: https://www.journalofdairyscience.org/article/S0022-0302(20)30760-8/fulltext >. Accessed: Apr. 30, 2024. doi: 10.1016/S0022-0302(20)30760-8.
» https://doi.org/10.1016/S0022-0302(20)30760-8.» https://www.journalofdairyscience.org/article/S0022-0302(20)30760-8/fulltext -
HAUSER, A. et al. Effect of heat stress and solar radiation on dry matter intake, biochemical indicators, production, and quality of Holstein and Jersey cows’ milk. Arquivo Brasileiro de Medicina Veterinaria e Zootecnia, v.75, n.4, p.721-734, 2023. Available from: <Available from: https://www.scielo.br/j/abmvz/a/M8YRQ6ZXZ89rP9Hf5xqyD7s/ >. Accessed: Apr. 30, 2024. doi: 0.1590/1678-4162-12884.
» https://doi.org/0.1590/1678-4162-12884.» https://www.scielo.br/j/abmvz/a/M8YRQ6ZXZ89rP9Hf5xqyD7s/ -
HECK, J. M. L. et al. Seasonal variation in the Dutch bovine raw milk composition. Journal of Dairy Science, v.92, n.10, p.4745-4755, 2009. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0022030209708045 >. Accessed: Apr. 30, 2024. doi: 10.3168/jds.2009-2146.
» https://doi.org/10.3168/jds.2009-2146.» https://www.sciencedirect.com/science/article/pii/S0022030209708045 -
HENNO, M. et al. Factors affecting the freezing point stability of milk from individual cows. International Dairy Journal, v.18, n.2, p.210-215, 2008. Available from: <Available from: https://www.sciencedirect.com/science/article/abs/pii/S0958694607001690 >. Accessed: Apr. 30, 2024. doi: 10.1016/j.idairyj.2007.08.006.
» https://doi.org/10.1016/j.idairyj.2007.08.006.» https://www.sciencedirect.com/science/article/abs/pii/S0958694607001690 -
HU, H. et al. The effect of heat stress on gene expression and synthesis of heat-shock and milk proteins in bovine mammary epithelial cells. Animal Science Journal, v.87, n.1, p.84-91, 2016. Available from: <Available from: https://pubmed.ncbi.nlm.nih.gov/26467738/ >. Accessed: Apr. 30, 2024. doi: 10.1111/asj.12375.
» https://doi.org/10.1111/asj.12375.» https://pubmed.ncbi.nlm.nih.gov/26467738/ -
ISLAM, M. A. et al. Automated Monitoring of Cattle Heat Stress and Its Mitigation. Frontiers in Animal Science, v.2, n.October, p.2-21, 2021. Available from: <Available from: https://www.frontiersin.org/articles/10.3389/fanim.2021.737213/full >. Accessed: Apr. 30, 2024. doi: 10.3389/fanim.2021.737213.
» https://doi.org/10.3389/fanim.2021.737213.» https://www.frontiersin.org/articles/10.3389/fanim.2021.737213/full -
KRISTENSEN, T. N. et al. Hsp72 is present in plasma from Holstein-Friesian dairy cattle, and the concentration level is repeatable across days and age classes. Cell Stress and Chaperones, v.9, n. 2, p.143-149, 2004. Available from: <Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1065294/ >. Accessed: Apr. 30, 2024. doi: 10.1379/CSC-17.1.
» https://doi.org/10.1379/CSC-17.1.» https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1065294/ -
MARINS, T. N. et al. Response of lactating dairy cows fed different supplemental zinc sources with and without evaporative cooling to intramammary lipopolysaccharide infusion: Intake, milk yield and composition, and hematologic profile. J. Anim. Sci., v.97, n.5, Mar. 7, 2019. Available from: <Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6488323/ >. Accessed: Apr. 30, 2024. doi: 10.1093/jas/skz082.
» https://doi.org/10.1093/jas/skz082.» https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6488323/ - MCGUFFEY, R. K.; SHIRLEY, J. E. History of Dairy Farming. Encyclopedia of Dairy Sciences (Second Edition), p.2-11, 2011.
- NRC. NATIONAL RESEARCH COUNCIL. Nutrient requirements of dairy cattle. 8.ed. Washington, DC: National Academy of Sciences, 2001. 381p.
- NRC. NATIONAL RESEARCH COUNCIL. A guide to environmental research on animals. 4.ed. Washington, DC: National Academy of Sciences, 1971.
-
PAUDYAL, S. Using rumination time to manage health and reproduction in dairy cattle: a review. Veterinary Quarterly, v.41, n.1, p.292-300, 2021. Available from: <Available from: https://pubmed.ncbi.nlm.nih.gov/34586042/ >. Accessed: Apr. 30, 2024. doi: 10.1080/01652176.2021.1987581.
» https://doi.org/10.1080/01652176.2021.1987581.» https://pubmed.ncbi.nlm.nih.gov/34586042/ -
PELIZZA, A. et al. Perfil metabólico de vacas Holandês e mestiças Holandês x Jersey no periparto. Arquivo Brasileiro de Medicina Veterinária e Zootecnia, p.1-11, 2019. Available from: <Available from: https://www.scielo.br/j/abmvz/a/5Vcv6qPGh7yfybYqQgB5P8c/ >. Accessed: Apr. 30, 2024. doi: 10.1590/1678-4162-10098.
» https://doi.org/10.1590/1678-4162-10098.» https://www.scielo.br/j/abmvz/a/5Vcv6qPGh7yfybYqQgB5P8c/ -
RENQUIST, B. J. Invited Review: Hypophagia and hypogalactia associated with heat stress. Applied Animal Science, v.35, n.1, p.49-56, 2019. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S1080744619300063 >. Accessed: Apr. 30, 2024. doi: 10.15232/aas.2018-01773.
» https://doi.org/10.15232/aas.2018-01773.» https://www.sciencedirect.com/science/article/pii/S1080744619300063 -
RHOADS, M. L. et al. Effects of heat stress and plane of nutrition on lactating Holstein cows: I. Production, metabolism, and aspects of circulating somatotropin. Journal of Dairy Science, v.92, n.5, p.1986-1997, 2009. Available from: <Available from: https://pubmed.ncbi.nlm.nih.gov/19389956/ >. Accessed: Apr. 30, 2024. doi: 10.3168/jds.2008-1641.
» https://doi.org/10.3168/jds.2008-1641.» https://pubmed.ncbi.nlm.nih.gov/19389956/ -
SAMKOVÁ, E. et al. Animal factors affecting fatty acid composition of cow milk fat: A review. South African Journal of Animal Sciences, v.42, n.2, p.83-100, 2012. Available from: <Available from: https://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000200001#:~:text=Cow%20individuality%20and%20the%20stage,to%20alter%20milk%20fat%20composition >. Accessed: Apr. 30, 2024. doi: 10.4314/sajas.v42i2.1.
» https://doi.org/10.4314/sajas.v42i2.1.» https://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S0375-15892012000200001#:~:text=Cow%20individuality%20and%20the%20stage,to%20alter%20milk%20fat%20composition - SAS. SAS ® UNIVERSITY EDITION. Statistical Analyses SystemSAS Institute Inc, 2017.
-
SCHIRMANN, K. et al. Validation of a system for monitoring rumination in dairy cows. Journal of Dairy Science, v.92, n.12, p.6052-6055, 2009. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0022030209713220 >. Accessed: Apr. 30, 2024. doi: 10.3168/jds.2009-2361.
» https://doi.org/10.3168/jds.2009-2361.» https://www.sciencedirect.com/science/article/pii/S0022030209713220 -
SILANIKOVE, N. Effects of heat stress on the welfare of extensively managed domestic ruminants. Livestock Production Science, v.67, n.October, p.1-18, 2000. Available from: <Available from: https://www.sciencedirect.com/science/article/abs/pii/S0301622600001627 >. Accessed: Apr. 30, 2024. doi: 0.1016/S0301-6226(00)00162-7.
» https://doi.org/0.1016/S0301-6226(00)00162-7.» https://www.sciencedirect.com/science/article/abs/pii/S0301622600001627 -
SMITH, D. L. et al. Short communication: Comparison of the effects of heat stress on milk and component yields and somatic cell score in Holstein and Jersey cows. Journal of Dairy Science, v.96, n.5, p.3028-3033, 2013. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0022030213001811 >. Accessed: Apr. 30, 2024. doi: 10.3168/jds.2012-5737.
» https://doi.org/10.3168/jds.2012-5737.» https://www.sciencedirect.com/science/article/pii/S0022030213001811 -
TAO, S. et al. Impact of heat stress on lactational performance of dairy cows. Theriogenology, v.150, p.437-444, 2020. Available from: <Available from: https://pubmed.ncbi.nlm.nih.gov/32173067/ >. Accessed: Apr. 30, 2024. doi: 10.1016/j.theriogenology.2020.02.048
» https://doi.org/10.1016/j.theriogenology.2020.02.048» https://pubmed.ncbi.nlm.nih.gov/32173067/ - TÖPEL, A. Chemie und Physik der Milch. Hamburg: Behr’s Verlag, 2016. 758 p.
-
WHEELOCK, J. B. et al. Effects of heat stress on energetic metabolism in lactating Holstein cows. Journal of Dairy Science, v.93, n.2, p.644-655, 2010. Available from: <Available from: https://www.sciencedirect.com/science/article/pii/S0022030210715071 >. Accessed: Apr. 30, 2024. doi: 10.3168/jds.2009-2295
» https://doi.org/10.3168/jds.2009-2295» https://www.sciencedirect.com/science/article/pii/S0022030210715071
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Editors
Rudi Weiblen (0000-0002-1737-9817)Rosangela Poletto Cattani (0000-0002-2096-1576)
