Effect of ambient management interventions on the production and physiological performance of lactating Sahiwal cattle during hot dry summer

Effects of rumen-protective γ-aminobutyric acid additive on lactation performance and serum biochemistry in heat-stressed cows

In the context of global warming, heat stress has become one of the major stress factors limiting dairy cattle production. Although many methods have been explored to help cows mitigate the negative effects of heat stress during the hot summer months, maintaining the performance of high-yielding cows under heat stress is still a great challenge. The aim of this trial was to investigate the effect of RP-GABA in the diet on milk yield, milk composition and serum biochemical parameters in heat-stressed cows. Twenty Chinese Holstein cows in early lactation (51.00 ± 4.92 kg milk/d, 71 ± 10.94 d in milk and 2.68 ± 0.73 parities) were included in this experiment and randomly divided into four groups (n = 5/group). The four experimental groups consisted of one control group (0 g RP-GABA/d) and three treatment groups, given 5, 7.5 and 10 g RP-GABA/d of dry matter (DM) per cow, respectively. The results showed that supplementing high-yielding cows with 10 g/d of RP-GABA improved milk protein production but had no effect on the improvement of other production performance, the alleviation of heat stress in cows, or the improvement of immune function and antioxidant capacity. Ultimately, we conclude that the supplementation of 10 g/d RP-GABA to heat-stressed, high-yielding dairy cows can provide a degree of performance enhancement. Furthermore, our study provides some reference for nutritional improvement measures for summer heat stress in dairy cows, especially high-yielding cows.

Heat ameliorative measures in Murrah buffalo (Bubalus bubalis) heifers during summer: effect on microclimate, thermal comfort, and behavior

Water buffalo (Bubalus bubalis) is the mainstay of milk production in Asian countries including India. However, the hot climate of the country remains the biggest bottleneck to exploit the potential of this species. Therefore, a study was conducted to assess the effect of heat ameliorative measures on microclimate, thermal comfort, and behavior of Murrah buffalo heifers during summer. Buffalo heifers (n = 24) between the age of 15 and 20 months with a mean body weight of 363.75 ± 11.27 kg were randomly grouped into four treatments based on their age and body weight. The heifers kept in the shed without any cooling served as CON (control), while the animals of group CJ were tied with a cooling jacket. The buffalo heifers of the CJF group were subjected to the cooling jacket with forced air ventilation, whereas the intermittent (10 min at 2-h intervals) sprinkling followed by forced air ventilation was practiced in group SF between 900 and 1800 h throughout the experiment. The microclimatic variables were low in the sheds of groups CJ, CJF, and SF than the CON. The physiological responses such as rectal temperature, skin temperature, respiration rate, and pulse rate were reduced in groups CJ, CJF, and SF than the CON at 1400 h. The serum cortisol was less in the CJF and SF than those of CON group. The animals of the CJ, CJF, and SF groups spent more time for feeding and rumination with less frequent longer bouts. The extended periods of lying followed by shorter standing and idling were observed in groups CJ, CJF, and SF when compared with the CON. It may be therefore concluded that cooling jacket and intermittent sprinkling in combination with forced air ventilation might be helpful in improving the micro-environment, thermal comfort, and behavior of buffalo heifers particularly under tropical climates during summer.

The Association between Gut Microbiome Diversity and Composition and Heat Tolerance in Cattle

Cattle are raised around the world and are frequently exposed to heat stress, whether in tropical countries or in regions with temperate climates. It is universally acknowledged that compared to those in temperate areas, the cattle breeds developed in tropical and subtropical areas have better heat tolerance. However, the underlying mechanism of heat tolerance has not been fully studied, especially from the perspective of intestinal microbiomics. The present study collected fecal samples of cattle from four representative climatic regions of China, namely, the mesotemperate (HLJ), warm temperate (SD), subtropical (HK), and tropical (SS) regions. Then, the feces were analyzed using high-throughput 16S rRNA sequencing. The results showed that with increasing climatic temperature from HLJ to SS, the abundance of Firmicutes increased, accompanied by an increasing Firmicutes to Bacteroidota ratio. Proteobacteria showed a trend of reduction from HLJ to SS. Patescibacteria, Chloroflexi, and Actinobacteriota were particularly highest in SS for adapting to the tropical environment. The microbial phenotype in the tropics was characterized by an increase in Gram-positive bacteria and a decrease in Gram-negative bacteria, aerobic bacteria, and the forming of_biofilms. Consistently, the functional abundances of organismal systems and metabolism were decreased to reduce the material and energy demands in a hot environment. Genetic information processing and information storage and processing may be how gut flora deals with hot conditions. The present study revealed the differences in the structure and function of gut microbes of cattle from mesotemperate to tropical climates and provided an important reference for future research on the mechanism of heat tolerance regulated by the gut microbiota and a potential microbiota-based target to alleviate heat stress.

Effect of cooling strategies on milk production, physiological variables and blood profile during hot-dry and hot-humid summer in Sahiwal cattle

The present experiment was undertaken to study the effect of misting and splashing during hot-dry and hothumid months in lactating Sahiwal cattle. The study was conducted during May, June (hot-dry) and July (hothumid) with monthly average temperature-humidity index (THI) of 79.88, 80.57 and 85.36, respectively. Eighteen lactating cattle were selected on the basis of days in milk, milk yield, and parity and then divided into three groups: control (no cooling), cooling by misting and cooling by splashing. Milk production was not affected by hot-dry and hot-humid heat stress in Sahiwal cattle. RT and RR were significantly lower in misting and splashing group as compared to control during hot-dry period. The heat stress-induced leucocytosis, lymphocytopenia and neutrophilia were significantly ameliorated by both misting and splashing during the study period. Heat stress-induced alterations in serum creatinine, sodium and ROS concentration were significantly mitigated by misting in hot-humid climate. The prolactin level significantly decreased in animals by misting during the study period. The results suggested that misting was more efficient than splashing as a cooling strategy in hot dry condition while splashing was more effective in hot-humid condition and mitigated the heat stress-induced alterations in different welfare parameters but could not fully nullify it. However, the resultant stress was not sufficient enough to decrease the milk yield in Sahiwal cattle. It may also be concluded that the Sahiwal cattle have high heat tolerance and could sustain production even in a hot-dry and hot-humid environment.

The future of smallholder farming in developing countries in the face of climate change: a perspective with a focus on Pakistan

The fragile balance in the world’s carbon equilibrium through the discovery of cheap carbon-based fuels in the nineteenth century has led to mass industrialisation and an explosion in the world human population, including that of Pakistan. Farmers worldwide will need to adapt their production systems to accommodate global warming and increased climate extremes resulting from these man-made environmental changes. The focus will need to be on smallholder farmers who generate 53% of the world’s food but who are least equipped to accommodate climate change. The most major limitation will be fresh water supply, no more exemplified than in Pakistan as Himalayan snowfall decreases and peak snow melt comes earlier in spring, limiting irrigation water for summer C4 crops such as corn, millet, sorghum and sugarcane. These are destined to replace the traditional C3 crops of wheat and rice, which will not be as suited to climate change conditions resulting from a projected mean 2°C rise in ambient temperature. Smallholder farmers will need to access superior-quality seed for crop cultivars for both human food and animal forage bred to withstand climatic change. Quantitative genetic selection programs for tropically adapted livestock must be implemented with a major focus on Pakistan’s Nili Ravi and Kundhi buffalo, together with Sahiwal cattle servicing the milk consumption needs of Pakistan’s burgeoning population of 211 million. The quality of forage available for livestock emanating largely from crop residues needs to be improved to meet the country’s greenhouse-gas production targets in line with international expectation. The challenge remains for governments to sustain marketing chains that allow them to be profitable when operating in an increasingly hostile environment. The conservation of soil fertility through increased carbon sequestration will be an important imperative. It is likely that females will play a more important role in directing adaptation in these communities. Successful adjustment will be dependent on effective extension programs working with all sectors of the community including males, females and children from all walks of life in both rural and urban environments. Failure to do so will lead to rapid increases in climate refugee numbers, which the world can ill-afford.

Behavioural, physiological, neuro-endocrine and molecular responses of cattle against heat stress: an updated review

The negative impact of heat stress on cattle growth, development, reproduction and production has been quite alarming across the world. Climate change elevates earth surface temperature which exacerbates the wrath of heat stress on cattle. Moreover, cattle in tropical and sub-tropical countries are most commonly affected by the menace of heat stress which severely wane their production and productivity. In general, cattle exhibit various thermoregulatory responses such as behavioural, physiological, neuro-endocrine and molecular responses to counteract the terrible effects of heat stress. Amongst the aforementioned thermoregulatory responses, behavioural, physiological and neuro-endocrine responses are regarded as most conventional and expeditious responses shown by cattle against heat stress. Furthermore, molecular responses serve as the major adaptive response to attenuate the harmful effects of heat stress. Therefore, present review highlights the significance of behavioural, physiological, neuro-endocrine and molecular responses which act synergistically to combat the deleterious effects of heat stress thereby confer thermo-tolerance in cattle.

Effect of fans and showers on the physiological measures and reproductive performance of Holstein Friesian bulls during subtropical summer

The objective of the current study was to determine the effect of fans and showers on the physiological measures and reproductive performance of Holstein Friesian bulls during subtropical summer in Pakistan. Thirty-six bulls with an average body weight of 898.0 ± 135.2 kg (mean ± SD) and an average age (4 to 6 years) were randomly divided into three treatment groups: (1) CTL, bulls kept under shade only; (2) FN, bulls provided with fans under shade; and (3) FNS, bulls provided showers in addition to fans under shade. The trial was carried out for 6 months from April to September 2016 and was categorized into two seasons (dry summer and humid summer). Ambient temperature, relative humidity, temperature-humidity index, dry matter intake (DMI), water intake, rectal temperature (RT), pulse rate (PR) and respiration rate (RR) were recorded daily. Semen characteristics and selected blood metabolites were measured every 2 weeks. The results indicated that the DMI of the bulls was similar between the treatment groups. Water intake, RT, PR and RR were significantly lower in the FNS group than in the CTL and FN groups (P < 0.001). Semen characteristics, including semen concentration, post-thaw semen motility, progressive motility, amplitude of lateral head displacement, straightness, live-to-dead ratio, plasma membrane integrity, normal acrosomal ridge and DNA integrity, were not different between the treatment groups (P > 0.05). The FNS group tended to have a higher semen volume than that of the FN and CTL groups (P = 0.10). Blood glucose levels were significantly lower in the FNS group than in the FN and CTL groups (P < 0.05). Blood urea nitrogen and testosterone were not different among the treatment groups (P > 0.05). The current results indicated that showers with fans improved the welfare of Holstein Friesian bulls by lowering physiological measures in addition to increasing trends in semen volume during subtropical summer.

Different ambient management intervention techniques and their effect on milk production and physiological parameters of lactating NiliRavi buffaloes during hot dry summer of subtropical region

In tropical countries, one of the major threats for diary animal production is climate change. Ambient management interventions are beneficial and are the dire need of animal production in tropics. Ambient management intervention and its effect on physiological performance of lactating NiliRavi buffaloes were investigated during the hot dry months (April to June) of Pakistan. Fifteen lactating NiliRavi water buffaloes of similar size, age, and same parity were randomly stratified into three groups, comprising of five animals in each group, designated as group S, SF, and SFS. Animals of group S (control) were kept just under the shade while the animals in group SF were provided shade plus fan, animals in group SFS were provided the shade, fan as well as sprinklers during the hot day hours between 10:00 AM to 6:00 PM. Shed conditions were same for all animals, isonitrogenous and isocaloric feed was provided to all animals. Milk production decreased with the increase in ambient temperature. Average dry matter intake in group S, SF, and SFS were 75%, 80%, and 90% of the total feed offered to the experimental animals, respectively. The mean rectal temperatures (°F) were 101.69, 101.19, and 100.85 in group S, SF, and SFS, respectively. Heat stress had pronounced effect on blood glucose level as indicated by the mean glucose concentration in group S and SFS being recorded at 78.04 mg/dl and 90.47 mg/dl, respectively. It is concluded that the buffaloes should be provided with sprinklers and fans to minimize heat load and maximize the production during hot dry season.