Do device that simulate methane capture equipment, as a mask located in the head of dairy cows affect their welfare?

Abstract

The objective of this study was to determine if device that simulate methane capture equipment (DSMC) located in the frontal part of the head of dairy cows affect animal welfare using productive, behavioral, biochemical and physiological indicators. Twenty Holstein dairy cows were assigned to one of the two following treatments: cows with DSMC (CDSMC, n=10) and cows without methane capture devices (CC, n=10). Treatment did not affect neither milk production nor biochemical blood. The group CDSMC tended to ruminate less (P=0.06) and tended to eat more (P=0.08) frequently than the group CC. In conclusion, considering the data set, the welfare of the cows was not significantly affected by the use of DSMC located in their heads.

Emissions of anthropogenic greenhouse gas (GHG) are of great concern due to its effects on climate change. It is estimated that the livestock sector contributes approximately 14.5% to the total GHG, of which methane (CH4) emissions from ruminants can represent between 40% and 45% [15]. In order to mitigate methane emissions from ruminants, different animal-based options have been explored: a) selective breeding or selecting animals through genetics; b) adjusting grazing intensities, as well as restoring degraded lands; c) the inclusion of crop by-products in the diet or natural plant extracts and enteric methane mitigation strategies; d) through the use of additives, reduce the production of CH4 of digestive origin emitted by the animals and manure management [10, 15, 18]. In this way, the use of methane capture devices that can neutralize it in other inert elements and that can be used by these animals in their production systems is a great challenge for green and clean production. While these devices are in the experimental stage, according to our knowledge, it is not known if such methane capture devices located in the front of the animals’ heads, such as a mask, affect their welfare in pasture-based dairy production systems.

According to Broom [3] “welfare of an individual is its state as regards its attempts to cope with its environment”, such that changes in systems and/or environments can affect animal welfare. It is recommended to assess animal welfare using a variety of indicators, such as behavioral, physiological, biochemical, productive and health indicators [2, 4, 5, 25]. More specifically in dairy cows, ruminating, grazing and lying down behaviors are clear indicators of welfare, given that in pasture conditions they dedicate more than 90% to these activities [2, 9, 16]. There are numerous and varied types of biochemical blood indicators of welfare and health in dairy cows. Some of these indicators are the different blood proteins. Abdel-Hamied and Mahmoud [1] reported that cows with mastitis had significantly lower blood concentrations of total proteins and globulins than healthy cows. Dairy cows subjected to the stress challenge of abrupt change in feeding and housing evidenced a marked decrease in ruminating time, and a decrease in some blood proteins, such as albumin [8]. The authors highlight the importance of using albumin as an indicator, given that it is a negative acute phase protein. In the same sense, the abrupt change of housing (tie-stall vs free-stall housing) in cows affected serum concentrations of total protein and albumin [24]. On the other hand, blood proteins, such as total proteins and globulins, are also influenced by the physiological stress of calving in dairy cows [22, 23]. In addition, due to stressful situations, immunosuppression and decreased globulins can make animals susceptible to diseases, thus affecting their health [6, 7]. Therefore, along with others, blood proteins (total proteins, globulins and albumin) can be used as biochemical indicators of welfare and health in dairy cows.

The use of equipment or elements located at or near the head could affect the welfare of the cows. As example, Johns et al. [17] reported that the use of a bell for a short period of time (3 days) affected the behavior of the cows (decreasing the time spent ruminating, lying down and feeding, as well as a decrease in head movements), which may affect your welfare. Therefore, placing methane capture devices in the front of the animals’ heads (mask type), being a foreign body, could affect the welfare of dairy cows. We hypothesize that the use of devices that simulate methane capture equipment (DSMC) located on the head of the cows can affect welfare; and if welfare is affected, it would be evidenced mainly during the first days of placing the device, then the animals would get used to it. In this sense, the objective of this study was to determine if DSMC located in the frontal zone of the head of dairy cows affect animal welfare using productive, behavioral, biochemical and physiological indicators.

Experimental protocol was evaluated and approved by the Comisión de Ética en el Uso de Animales (CEUA-FVET-1179, 111900-000919-20), Universidad de la República, Montevideo, Uruguay. The study was conducted at the farm of the “Escuela de Lechería de Nueva Helvecia (CETP-UTU/UTEC)” located in the department of Colonia, Uruguay.

Twenty Holstein dairy cows with an average live weight of 595.3 ± 51.3 kg, days in milk (DIM) of 142.2 ± 40.3 and number of lactations of 2.7 ± 0.7 were used. All cows were under the same management and feeding conditions throughout of the experimental period. Cows were blocked by DIM, number of lactation and live weight in two groups or treatments, and which group received the device was randomly assigned: cows with DSCM (CDSCM, n=10, average live weight of 597.9 ± 54.3 kg, DIM: 140.8 ± 38.6 and number of lactations of 2.6 ± 0.7) and cows control, without methane capture devices (CC, n=10, average live weight of 592.6 ± 50.9 kg, DIM: 143.5 ± 43.9 and number of lactations of 2.7 ± 0.7).

The device simulating methane capture (DSCM) equipment (weighing about 300 g) was similar to a conventional head harness. As shown in Fig. 1, at the top of the snout (below the eyes, but above the snout) one of the harness straps was passed through and continued with a sole material towards the end of the nose and extending 3 centimeters more approximately. In terms of width, the rubber was folded in the shape of an inverted U and slightly exceeded the width of the animal’s snout (Fig. 1). It is highlighted that the devices used in this study that simulate methane capture equipment did not have the circuit and electrical elements. For this reason, in this study we refer to a device that simulates the methane capture equipment, such as a mask. The difference between the equipment that was used in this study and the one that could be used in practice is precisely the circuit and electrical element, which weighs 1 kg and has the following dimensions 15 × 10 × 3 cm, and would be located in the neck. Our team has used only a couple of complete devices (mask and electrical elements) as a test, and was possible to capture methane, for which it is a prototype that could be viable.

Fig. 1.

The device used isolated from the animal is shown in image A, and the device placed in the head of grazing dairy cows is shown in images B and C.

Body weight was recorded at day −7 and at day 28 after placement of the device on the animals’ heads. The pasture used was composed of Dactylis perseo, Alfalfa Medicago sativa and Festuca arundinace, to provide a daily forage intake of 14 kg DM per cow. In addition, cows received 3 kg DM corn grains during each milking. All cows were milked twice a day at 06:30 and 16:30 hr. Milk production was individually recorded with Waikato^® meters. Milk samples were taken at −6, 2, 7, 14, 21 and 27 days after placing the methane capture device on the animals.

Blood samples were taken from coccygeal vein into 5‐ml, after morning milking, at −5, 1, 8, 15, 22 and 29 days after placing the methane capture device on the animals. The samples were centrifuged at 2,500 × g, 10 min to obtain the serum or plasma and were stored at −20°C. Blood biochemistry was analyzed using BioSystem commercial kits (Bio-System, Barcelona, Spain) at the Laboratorio de Bioquímica (Facultad de Veterinaria, Universidad de la República, Uruguay). The concentration of globulins was determined by the difference between the concentration of total proteins and albumin [11, 16].

Behavior (eating, ruminating and inactive) data were collected by “CowScout” sensor systems (GEA Farm Technologies, Aktiengesellschaft, Bönen, Germany) which were attached to the neck collar [13]. Data were recorded daily from day −6 to day 28, in relation to the moment of placing the methane capture device on the animals.

Data from temperature‐humidity indexes are shown in Supplementary Fig. 1 [19, 20].

The data obtained from the collars from the 6 days prior to the placement of the devoice were averaged per animal, and the average of the previous days was included in the model as a Covariate. In the blood variables, day −5 prior to device placement, as well as milk production on day −6 prior to device placement, were considered as Covariate in the model. The body weight was analyzed with two-way repeated ANOVA. All data were analyzed by ANOVA for repeated measurements, using the SAS mixed procedure (SAS Studio, SAS OnDemand for Academics). Treatment (CC vs. CDSCM), Time (day) and the interaction between treatment and time were included as fixed effects in the model. The animal within each treatment was considered as a random effect. Results are expressed as the mean ± SEM. Significant differences were considered with an alpha ≤0.05, and a trend between 0.05 and 0.10.

Milk production was not affected by treatment (F_(1,18)=1.70, P=0.209), nor did the interaction between treatment and time (F_(4,72)=0.31, P=0.872), but there was a significant effect of time (F_(4,72)=8.53, P<0.0001, see Supplementary Fig. 2).

Treatment did not affect any of the blood biochemical indicators analyzed: total protein (F_(1,18)=1.70, P=0.524), albumin (F_(1,18)=0.09, P=0.874), globulin (F_(1,18)=0.47, P=0.955), and glucose (F_(1,18)=0.75, P=0.233). There was no significant interaction between treatment and time in any of them (total protein: F_(4,72)=0.89, P=0.47; albumin: F_(4,72)=0.43, P=0.78; globulin: F_(4,72)=1.04, P=0.39; glucose: F_(4,72)=1.30, P=0.17). Albumin (F_(4,72)=3.22, P=0.02) and glucose (F_(4,72)=12.09, P<0.0001) concentrations varied over time (see Supplementary Fig. 2), but total protein (F_(4,72)=0.37, P=0.37) and globulin (F_(4,72)=1.32, P=0.26) concentrations did not.

The group CDSCM tended to ruminate less (F_(1,18)=4.06, P=0.060) and tended to eat more frequently (F_(1,18)=3.28, P=0.087) than the group CC (Fig. 2). Treatment did not affect inactive behavior (F_(1,18)=0.05, P=0.83). In all recorded behaviors there was a significant effect of time (ruminate: F_(28,504)=12.56; eat: F_(28,504)=18.60; inactive: F_(28,504)=17.14; P<0.0001), but there was no significant interaction between treatment and time (ruminate: F_(28,504)=0.65; eat: F_(28,504)=1.20; inactive: F_(28,504)=1.44; P>0.05).

Fig. 2.

Percentage of daily time (%) in which cows with methane capture devices (-●-) and cows without methane capture devices (-○-) were observed eating (A), ruminating (B) and inactive (C).

There was no significant effect of treatment on body weight (F_(1,18)=0.18, P=0.679). There was no significant effect of time (F_(1,18)=1.21, P=0.285) or interaction between treatment and time on body weight (F_(1,18)=1.01, P=0.328).

Within the great objectives of veterinary science, ensuring the care and welfare of animals is a priority [12]. Although the use of equipment that allows capturing the methane located in the head of the cows is in process, it is essential to know if these foreign bodies represent a threat or affect the welfare of these animals. In this sense, this study showed that the use of device that simulates methane capture equipment located on the head of dairy cows did not significantly affect their welfare. This fact is relevant, because when systems or equipment are fine-tuned to improve clean production conditions in production systems, animal welfare is not always evaluated. In addition, when animals are subjected to new management systems and/or equipment that are strange or unfamiliar to them, they can become stressed and lead to changes in their behaviors (such as eating less food and presenting immunosuppression), which could predispose them to diseases and therefore affect their welfare and health [4, 14, 21, 25].

The cows to which the device that simulates methane capture equipment were placed in their heads did not show significant changes in the different variables (behavior, blood biochemistry, body weight and milk production). Therefore, in general terms, the welfare of the cows was not significantly affected by the use of the methane capture devices located in their heads. However, there was only one trend to eat more and ruminate less in the group treated with the device. Ruminating and eating behaviors in pasture-based systems are important indicators of welfare [2, 9]. The cows with the device tended to ruminate less, which could indicate that their welfare might be affected. But on the other hand, cows with the device also tended to eat more in this pasture-based systems. In addition, although it has been reported that abrupt stressful challenges can modify the concentration of blood proteins [8, 22,23,24], in our study, the use of the DSCM did not generate significant changes in the blood proteins evaluated. These results on internal indicators of the animal reinforce the fact that such devices did not affect welfare. During one month of evaluation, the animals did not show changes in body weight or in milk production, showing that the use of these devices did not affect physiological and productive indicators either. Therefore, taking into account that the changes in behavior were trends and that these changes were also in different directions depending on the behavior (less frequent rumination and greater frequency eating), and that other indicators were not affected, the welfare of these animals as a whole was not significantly and negatively affected.

Although the device that simulates the methane capture equipment did not significantly affect the welfare of the cows, it is important to note that this study was evaluated for only one month. We had hypothesized that (because of the novelty for the animal of something unknown) the main changes would be seen during the first days after the placement of the device. As we did not find clear effects, not only during the first days, but also during the month that they used it, we consider it unlikely that the animals could be affected in the long term. In any case, it is important to highlight that our results were evaluated in a short period of time (one month), and that more studies are needed to know if these devices can affect long-term cow welfare.

The objective of looking for different alternatives to reduce the emission of greenhouse gases and at the same time find possibilities that contemplate animal welfare is a great challenge for green and clean production. In this sense, this work leaves open the possibility of using these methane capture devices located in the head of dairy cows kept in grazing systems, without negatively affecting their welfare. In conclusion, the welfare of the cows was not significantly affected by the use of the device that simulate methane capture equipment located in their heads, although they tended to ruminate less and to eat more frequently than the cows without the device.

CONFLICT OF INTEREST

The authors declare that there is no conflict of interest.