**5. Modifications of the environment under grazing conditions. Animal response**

#### **5.1. Shades**

226 Milk Production – An Up-to-Date Overview of Animal Nutrition, Management and Health

**Figure 1.** Milk yield for the three experimental periods in a trial with treatments containing different amounts of total dissolved salts (TDS): 1,000; 5,000 and 10,000 mg/L in the drinking water. Periods lasted 28 days each, and the different treatment waters were formulated to have not less than 100, 850 and 2000 mg SO42-/L for treatments 1,000; 5,000 and 10,000 mg/L TDS, respectively. All animals were

Period 1 Period 2 Period 3

Amylolytic bacteria (x109) 3.4 3.4 3.6 0.89 0.98 Cellulolytic bacteria (x106) 20.5 31.9 14.5 0.55 0.81 Protozoa (x103/ml ) 9.3 13.8 12.9 0.46 0.25 **Table 7.** Ruminal amylolytic and cellulolytic bacteria and protozoa at sampling time 0 for treatments containing different amounts of total dissolved salts: 1,000; 5,000 and 10,000 mg/L in the drinking water.

Acetate (A) 76.51 74.03 75.29 0.42 0.46 0.71 <0.0001 0.90 Propionate (P) 24.7 24.4 23.3 0.16 0.17 0.66 <0.0001 0.98 Isobutyrate 1.61 1.74 1.45 0.14 0.92 0.32 0.0025 0.30 Butyrate 11.55 11.26 11.17 0.34 0.63 0.89 0.0002 0.94 Isovalerate 1.72 1.60 1.41 0.31 0.69 0.18 <0.0001 0.94 Valerate 1.21 1.20 1.07 0.10 0.76 0.45 0.0004 0.94 Total 117.5 114.6 113.9 0.27 0.35 0.79 <0.0001 0.95 pH 6.37 6.37 6.36 0.30 0.71 0.41 <0.0001 0.98

mg/dL 7.65 8.07 8.41 0.39 0.68 0.49 <0.0001 0.94

**Table 8.** Ruminal volatile fatty acids, pH and ammonia concentration for treatments containing different amounts of total dissolved salts: 1,000; 5,000 and 10,000 mg/L in the drinking water.

**Item** Treatment Effects

1,000 5,000 10,000 T P

1,000 5,000 10,000 Per Col Treat Hour TxH

subjected to all treatments, since data were obtained and analyzed in a cross-over design.

**Measurement Treatment Contrast**

VFA, mol/mL:

0

4

8

12

16

Milk yield (kg/cow/day)

20

24

28

Ammonia,

During summer, the operations should consider the strategic enclosure in a shaded pen between milkings (Valtorta et al., 1996), so as to reduce the heat load and reduce the walking distances. In addition, the adequacy of milking schedules within this scheme would take advantage of both peaks as grazing pasture at night (Davison et al., 1996).

In a study performed in the central dairy area of Argentina (Valtorta et al., 1996) four groups of cows were compared. Two of them were locked between 09:00 and 16:00 in a pen adjacent to the parlor, which possessed an artificial shade structure and water *ad libitum*. The other two had no access to shade. Within each treatment, with and without shade, one of the groups received supplementation with concentrate, 3.5 kg / **v** cow/ d of corn grain. The strategic provision of shade improved the comfort of the grazing animals. The increase in rectal temperature between morning and afternoon had an average of 0.28 º C for animals with access to shade and 1.1 º C for those exposed to the sun. As for breathing rate, the differences were 10.5 and 23.4 rpm, respectively.

The strategic provision of shade had a similar impact to the energy supplementation, and the combination of both practices significantly increased milk production. The concentrate also produced an increase in the concentration of milk protein (Table 9).


**Table 9.** Milk production (MP) and milk fat (F) and protein (P) in milk of multiparous cows in late lactation, managed with and without access to shade (strategic shading from 09:00 to 16:00), and with or without concentrate in their ration (3.5 kg conc/c/d)

In this study, the grazing patterns adapted to confinement. Grazing time recovered during the peaks, especially during the early hours of the day.

The average maximum temperature was 29 º C and relative humidity 72%. The activity was concentrated in two well-marked periods: from dawn, at 05:00, and 09:00 and between 16:00 and 22:00. Enclosure time was offset by increased activity in those periods. Evening grazing, of somehow greater relative importance, ended after sunset, indicating some degree of nocturnal activity.

## **5.2. Animal cooling**

With respect to the direct cooling of the animal, using a system as described, in Argentina the effectiveness of pre-milking refrigeration has been evaluated (Valtorta & Gallardo, 2004). Cows were cooled for 20 min prior to both milkings through a combination of sprinkling and continuous ventilation. Sprinklers produced large droplets that penetrated the coat, their water consumption being 30 l/h. The cooling system improved cow comfort, measured in terms of the significant decrease in rectal temperature and respiratory rate.

Cooled cows produced more milk with higher fat content and yield and protein (Table 10).


differences were 10.5 and 23.4 rpm, respectively.

without concentrate in their ration (3.5 kg conc/c/d)

nocturnal activity.

**5.2. Animal cooling** 

the peaks, especially during the early hours of the day.

advantage of both peaks as grazing pasture at night (Davison et al., 1996).

also produced an increase in the concentration of milk protein (Table 9).

distances. In addition, the adequacy of milking schedules within this scheme would take

In a study performed in the central dairy area of Argentina (Valtorta et al., 1996) four groups of cows were compared. Two of them were locked between 09:00 and 16:00 in a pen adjacent to the parlor, which possessed an artificial shade structure and water *ad libitum*. The other two had no access to shade. Within each treatment, with and without shade, one of the groups received supplementation with concentrate, 3.5 kg / **v** cow/ d of corn grain. The strategic provision of shade improved the comfort of the grazing animals. The increase in rectal temperature between morning and afternoon had an average of 0.28 º C for animals with access to shade and 1.1 º C for those exposed to the sun. As for breathing rate, the

The strategic provision of shade had a similar impact to the energy supplementation, and the combination of both practices significantly increased milk production. The concentrate

**Shade Concentrate** MP, l/c/d F, % P, % **NO NO** 15.3 3.55 2.81 **NO YES** 16.8 3.69 2.96 **YES NO** 16.9 3.49 2.77 **YES YES** 19.2 3.61 2.,85 **Table 9.** Milk production (MP) and milk fat (F) and protein (P) in milk of multiparous cows in late lactation, managed with and without access to shade (strategic shading from 09:00 to 16:00), and with or

In this study, the grazing patterns adapted to confinement. Grazing time recovered during

The average maximum temperature was 29 º C and relative humidity 72%. The activity was concentrated in two well-marked periods: from dawn, at 05:00, and 09:00 and between 16:00 and 22:00. Enclosure time was offset by increased activity in those periods. Evening grazing, of somehow greater relative importance, ended after sunset, indicating some degree of

With respect to the direct cooling of the animal, using a system as described, in Argentina the effectiveness of pre-milking refrigeration has been evaluated (Valtorta & Gallardo, 2004). Cows were cooled for 20 min prior to both milkings through a combination of sprinkling and continuous ventilation. Sprinklers produced large droplets that penetrated the coat, their water consumption being 30 l/h. The cooling system improved cow comfort, measured

Cooled cows produced more milk with higher fat content and yield and protein (Table 10).

in terms of the significant decrease in rectal temperature and respiratory rate.

**Table 10.** Productivity of cows with (R) or without (NR) a 20 min refrigeration in the holding pen before milkings

In Israel cows are cooled using a similar system, on the basis of increasing evaporation from the body surface and the respiratory tract. In that case, they use the combination of large drops that penetrate the animal coat, produced by sprinkler consuming 300 to 500 l / h and forced ventilation, both in the holding pen and in the resting area. The cooling is done in cycles in which combine spraying (30 sec) followed by ventilation (4.5 min), in cycles of 30- 45 min. This system is used in Israel at 2-3 hours intervals, 6-10 times per day. High producing cows are maintained in situation of normal body temperature for most of the day. Also, significantly increases in milk production and reproductive efficiency are obtained (Flamenbaum, 2010, 2008; Flamenbaum & Ezra, 2007, 2003).

According to Flamenbaum (2008) in Israel it has being shown that this intensive cooling system, applied in transition cows, can reduce the loss that causes the hot season in the level of milk production and pregnancy rate.

During summer, the combination of a proper cold treatment with an adequate body condition at calving and a good feeding management to early lactation have the potential to enable production and fertility levels almost similar to those obtained in winter. In high production herds productive summer performance is 96 to 100% of that obtained in winter, while, if not intensive cooling is applied, this ratio varies between 86 and 88% (Flamenbaum, 2008).

The implementation of these management strategies in most dairy farms in Israel have had the potential to level up the supply of milk to the market throughout the year. These measures help to increase the efficiency of milk production, giving the Israeli dairy industry a greater degree of competitiveness against the threat of importing milk powder in the summer. In connection with the modification of environmental factors, they have tried to determine if intensive cooling can prevent productive and reproductive losses in highproducing cows (Flamenbaun & Galon, 2010). The results are presented in Table 11.

The results show that intensive cooling during summer reduced the decrease in conception rate by about 50%, even in extremely high production cows. Over the years the Israeli extensionists found the need to develop tools to monitor the effectiveness of cooling systems.

Also, if during late gestation, or dry period, the environment is manipulated, so as to ease the stress of summer, cows can increase the later milk production. In a study by Amaral et al. (2009), dry advanced pregnant cows that underwent a refrigeration system increased the subsequent production, as compared to untreated animals. In this study, cows were

subjected to daily refrigeration for a period of 46 days pre-calving. After calving all cows were managed together in a barn equipped with sprinklers and fans. With this management cow milk production was significantly higher during the first 30 weeks of lactation.


**Table 11.** Milk production and conception rate of low and high production cows with intensive (I) or moderate (M) cooling in Israel

Although the physiological mechanisms involved in such responses are not fully understood (Avendano-Reyes et al., 2010), various hormonal actions may be implicated.

In Argentina, these management systems may have special connotations, given the trend towards intensification in the dairies.

## **5.3. Combination of feeding and environmental management**

Since both nutritional and environmental factors affect the performance of dairy cows in the central basin of Argentina, a trial was designed to evaluate the combined effects of diet and pre-milking cooling with sprinklers and fans (Gallardo et al., 2005). Responses of rectal temperature, respiratory rate, and milk production and composition were evaluated. Cows were assigned to four treatments, consisting of the combination of two diets: control (CD) and balanced (BD) with two levels of cooling before milkings: Sprinklers and fans (SF) or nothing (NSF).

In order to obtain different Forage: concentrate (F:C) ratios (about 80:20 in CD and 70:30 in BD) grazing in the DB group was restricted. The CD was prepared according to common practices in the area, while the DB was calculated to obtain better protein, energy and lipids balance. Based on the quality of its components, the energy density of diets was 1.48 Mcal of NEL / kg DM and 1.60 Mcal ENL / kg DM for CD and BD, as calculated according to NRC (2001).

In addition, SF animals received a combination of spray and ventilation for 20 min before the morning milking and 30 min before the afternoon milking in the holding pen.

Rectal temperatures (RT) and respiratory rate (RR) were recorded before and after the afternoon milking. As a result of cooling, both RT and RR were lower after milking in the SF groups, compared to non-refrigerated or NSF. The production and milk protein concentration were higher for the BD. The authors speculated that this increase in production could be due to the higher density of the diet, which would provide enough energy to increase production under conditions of heat stress. Similar results were observed by Drackley et al. (2003) when offering diets with 1.60 Mcal NEL/kg DM to cows in mid lactation. The controls received a diet with 1.52 Mcal NEL/kg DM during the summer.

No effects on the variation of body condition were detected, which would indicate that the factors acted in a way that energy was derived more efficiently to produce milk.

The diet did not affect urea-N in milk. However, this parameter was affected by cooling. Probably the cooling produced a decrease in the demand of energy to remove extra body heat, leaving more energy available for milk production. Also, the balance of the diet by manipulating the ratio F: C could have given greater availability of energy for microbial protein synthesis that may result in increased milk protein. It is possible that there was an increased use of ammonia in the rumen, also considering the increased consumption of protein in the BD. On the other hand, there might have been less use of amino acids as a source of energy in the refrigerated treatments.

These results show that under grazing conditions, the effects on production and milk composition are enhanced when diets are specially formulated for warm periods. All this environmental managements, together with the provision of large amounts of water, help improve the efficiency of water use in dairy cattle during hot periods.
