Effect of multiple stress factors (thermal, nutritional and pregnancy type) on adaptive capability of native ewes under semi-arid environment

Seasonal variations in botanical and nutritive composition, forage availability and ingestive behavior of grazing goats in the semiarid region

The aim of this study was to assess how the different seasons of the year impact the botanical composition, availability, and quality of forage in the caatinga, as well as the frequency of ingestion and ingestive behavior of goats in a semi-arid region. The experiment used four crossbred castrated males, with an average weight of 30.2 ± 4.76 kg and an average age of 20 months. The experimental period lasted for 12 months, encompassing two rainy seasons and one dry season within this timeframe, with three replications (data collection) per season. All collected forage was categorized based on its stratum (herbaceous, woody, and litter), and a chemical composition analysis was conducted. The goats' behavior was assessed by observing variables such as feeding time, idleness, rumination, displacement, social interaction, and water intake. The findings revealed clear seasonality in both availability and quality of forage, consequently influencing the botanical composition of the goats' diet and their ingestive behavior. In addition, during the grazing period, the goats showed a shift grazing habit, in which idle and feeding peaks were alternated with increased displacement during the morning and rumination in the afternoon. The seasons of the year strongly impact the availability and nutritional quality of forage in the caatinga biome, consequently influencing the ingestive behavior and dietary composition of goats in this ecosystem.

Effects of heat-stress-reducing systems on blood constituents, milk production and milk quality of Holstein and Jersey cows and heifers on pasture

The objective of this study was to evaluate the influence of different heat-stress-reducing systems, i.e., sprinkler + artificial shade, shower + artificial shade, and artificial shade, on serum mineral, hormonal, hematological, and metabolite profiles, on milk production, and milk composition in lactating cows and pubertal heifers of Holstein and Jersey breeds. For this purpose, 12 animals were used: 3 Holstein cows with an average (mean ± SD) body weight of 600 ± 30 kg, 53 ± 11 months of age, and milk yield of 27 ± 3.5 kg/day; 3 Jersey cows with an average body weight of 370 ± 11 kg, 40 ± 6 months of age, and milk production of 11 ± 1.5 kg/day; 3 Holstein heifers (325 ± 25 kg and 16 ± 0.6 months of age); and 3 Jersey heifers (250 ± 25 kg and 13 ± 0.6 months of age). Animals were used in a replicated 3 × 3 Latin square design with a 3 × 2 × 2 factorial arrangement of treatments that included three treatments (sprinkler + artificial shade, shower + artificial shade, and artificial shade), two breeds (Holstein, Jersey), and two physiological stages (lactating cows, heifers). The experimental treatments influenced (P < 0.05) the concentrations of triiodothyronine, with the shower and shade systems showing greater and similar concentrations (99.5 and 96.3 µg/dL, respectively) when compared with sprinkler treatment (89.2 µg/dL). There was an effect (P < 0.05) of breed on the concentrations of Na + , K + , hemoglobin, hematocrit and mean corpuscular volume levels with the Holsteins having lower levels of Na + , K + , hemoglobin, hematocrit and mean corpuscular volume (101.1, 4.0 ng/mL, 11.2 g/dL, 24.7%, and 42.3 μm3, respectively) than the Jerseys (106.5 and 4.3 ng/mL, 12.4 g/dL, 27.7%, and 46.3 μm3, respectively. Total cholesterol and high-density lipoproteins were influenced by physiological stage (P < 0.05). Concentrations of cholesterol and high-density lipoproteins were higher for cows (94.1, and 56.9 mg/dL, respectively) than for heifers (56.9 and 42,9 mf/dL, respectively). Milk production and fat content were affected (P < 0.05) by breed (P < 0.05), with Holstein cows producing more milk (23.9 kg/day) than Jersey cows (12.0 kg/day), but Jersey cows had higher fat concentration (4.6%) than Holstein cows (3.0%). Therefore, the three different thermal-stress-reducing-systems tested were able to maintain the serum biomarkers within normal physiological ranges. However, the most appropriate thermal-stress-reducing-systems would be a sprinkler systema because it uses less water compared with the shower system.

Effect of nutritional stress on physiological parameters and seminal attributes of native-crossbred ram in semi-arid tropics

A prolific three-breed (Malpura, Patanwadi, and Garole) cross Avishaan sheep has been developed in the semi-arid zone to improve farmer's income. Nutritional scarcity is a major limitation in animal husbandry during the dearth period of semi-arid tropics. Therefore, before the inaugural launch of the breed into the field, a study was designed to evaluate the effect of nutritional stress on physiological parameters and seminal attributes of native-crossbred rams in semi-arid tropics. Thus, 16 native adapted (Malpura) and 16 native-crossbred rams were equally distributed into four groups, namely, native control (G1), native nutritional stress (G2), native-crossbred control (G3), and native-crossbred nutritional stress (G4). Both the control groups (G1 and G3) were kept on their maintenance requirement as per their body weight, whereas the nutritional stress groups (G2 and G4) were provided 30% less than their maintenance requirement. The body weight of G4 decline (P<0.05) as compared to their initial weight. The plasma glucose level of G2 and G4 reduced (P<0.05) in comparison with G1 and G3, respectively. The total motile sperm percentage, rapid motile sperm percentage, and sperm viability decrease significantly (P<0.05) within the acceptable limit in native-crossbred rams (G4) under nutritional scarcity. However, the similar blood biochemical along with acceptable seminal attributes of all the rams reflected that native-crossbred rams can cope with the nutritional scarcity in semi-arid tropics and have the potential to contribute to the sustainable small ruminant production system for livelihood security in this region.

Resilience of Small Ruminants to Climate Change and Increased Environmental Temperature: A Review

Simple Summary

Small ruminants are critical for food security and livelihood, especially under extreme stressful and diverse climatic environments. Generally, sheep and goats are farmed on grazing land in relatively large groups relying on low inputs in terms of feed, water and labor, and possess high thermotolerance compared to large ruminants such as cattle. Climate change has been recognized as a harmful factor influencing sheep and goat production. Small ruminants are vulnerable to direct and indirect effects of climate change, including heat stress, limited and low-quality pasture availability and emerging infectious diseases. In this context, selection of animals for thermotolerance is one viable strategy that exploits natural variation within and between breeds for desirable traits. The various biological markers used to improve thermotolerance in small ruminants include behavioral (feed intake, water intake), physiological (respiration rate, rectal temperature, sweating rate), hormonal (T3, T4 and growth hormone) responses and the response of molecular regulators.

Abstract

Climate change is a major global threat to the sustainability of livestock systems. Climatic factors such as ambient temperature, relative humidity, direct and indirect solar radiation and wind speed influence feed and water availability, fodder quality and disease occurrence, with production being most efficient in optimal environmental conditions. Among these climatic variables, ambient temperature fluctuations have the most impact on livestock production and animal welfare. Continuous exposure of the animals to heat stress compromises growth, milk and meat production and reproduction. The capacity of an animal to mitigate effects of increased environmental temperature, without progressing into stress response, differs within and between species. Comparatively, small ruminants are better adapted to hot environments than large ruminants and have better ability to survive, produce and reproduce in harsh climatic regions. Nevertheless, the physiological and behavioral changes in response to hot environments affect small ruminant production. It has been found that tropical breeds are more adaptive to hot climates than high-producing temperate breeds. The growing body of knowledge on the negative impact of heat stress on small ruminant production and welfare will assist in the development of suitable strategies to mitigate heat stress. Selection of thermotolerant breeds, through identification of genetic traits for adaption to extreme environmental conditions (high temperature, feed scarcity, water scarcity), is a viable strategy to combat climate change and minimize the impact on small ruminant production and welfare. This review highlights such adaption within and among different breeds of small ruminants challenged by heat stress.

Combined effect of heat and nutritional stress on superovulation of Malpura ewes in a semi-arid region

Sheep reared in hot semi-arid environments are generally exposed to heat and nutritional stress in some seasons of the year, which affects both production and reproduction. To assess the effect of high ambient temperature and feed scarcity on superovulation, 16 adult Malpura ewes were randomly divided into two groups of 8 animals each. G1 (control) was kept under a shed and offered a maintenance diet, and G2 (combined stress) was subjected to both nutritional (30% less of maintenance diet) and heat (38-44 °C for 6 h/day) stress. Ewes were superovulated without estrus synchronization by a combination of single injection of 200 IU eCG and 8 injections of FSH (Folltropin-V) at 12-h intervals in tapering doses of 5 mg/kg body weight, starting from the day 7 of natural estrus. eCG was given with the first injection and PGF2α (10 mg) was given with the second last FSH injection. G2 increased respiration rate and rectal temperature (P < 0.01), and blood urea level (P < 0.05), whereas it decreased average daily gain, plasma T4 concentration (P < 0.01) and body weight (P < 0.05). Plasma estradiol level was lower (P < 0.05) in G2 ewes as compared to control (G1) ewes. However, the number of ewes showed a superovulatory response (88 vs 66% ewes ≥ 3 corpus luteum), ovulation rate (8.75 vs 5.88) and embryo production (5.5 vs 3.9) decreased, and the number of large follicles (anovulation) increased (1.0 vs 2.14) in G2 ewes. G2 had a comparable effect on the superovulatory response compared to control ewes although physiological changes occurred as an adaptive mechanism to stress. Therefore, the well-adapted cyclic sheep of the semi-arid region may be used for superovulation despite the stressful condition of heat exposure and nutritional insufficiency.

Environmental effects on collared peccaries (Pecari tajacu) serum testosterone, testicular morphology, and semen quality in the Caatinga biome

The objective of the study was to understand the influence of climatic variations in a semiarid environment on serum testosterone, testicular morphology and semen quality in collared peccaries (Pecari tajacu). Reproductive metrics (semen quality, testicular morphometry and testosterone serum profiles) of 10 mature males were measured monthly for 18 months. Meteorological data (rainfall, air temperature, relative humidity, wind speed and radiant heat load) also were recorded during the same period. Rainfall regimes were classified in different classes (Class 1: months with no rain; Class 2: months with up to 50 mm of rain; and Class 3: months with >50 mm of rain). Among rainfall classes, average air temperature (°C) and relative humidity (%) were different. Climatic changes between rainfall classes did not lead to overall variations of testicular size, testosterone production, and semen metrics. However, relative humidity recorded before semen collection (one day, one week, or over 51-55 days) was positively correlated (P < 0.05) with semen motility metrics (total motility, beat cross frequency and straightness) and sperm subpopulations (medium and static sperm), as well as with volume. Negative correlations (P < 0.05) were revealed between air temperature and the same semen motility patterns and volume. Additionally, radiant head load measured on the day of semen collection negatively influenced (P < 0.05) sperm straightness. This study demonstrates for the first time that no seasonal changes could be detected overt the 18-month period on the serum testosterone, testicular morphology and semen quality of collared peccaries raised in the Caatinga biome; however, it is expected that long term environmental changes will influence the reproductive physiology of species leaving in that habitat.

Diurnal thermoregulatory responses in pregnant Yankasa ewes to the dry season in a tropical Savannah

The study investigated concomitant effect of gestation and high ambient temperature under a tropical environment on rectal temperature (RT), respiratory rate (RR) and heart rate (HR) responses in Yankasa ewes. Twenty Yankasa ewes, consisting of ten pregnant and ten non-pregnant ewes, were used for the study. Ewes were synchronised and bred, such that each gestation phase coincided with different periods of the dry-seasons, early-gestation (cold/harmattan), mid-gestation (peak hot-dry) and late-gestation (late hot-dry). The RT, RR and HR were recorded thrice, 2 days apart at middle of each gestation period at 06:00, 14:00 and 18:00 h, concurrently with dry- (DBT) and wet-bulb temperatures of the experimental pen. The DBT was positively correlated with RT, RR during the different gestation stages. The RT significantly (P < 0.001) increased with the hour of day, regardless of the physiological status of the ewes, with peak at 14:00 h. Values of RT and RR were higher (P < 0.05) in pregnant than non-pregnant ewes at mid- and late-gestation, respectively. Mean RT was lower (P < 0.001) at 06:00 h in pregnant than non-pregnant ewes at early-gestation (cold-dry). The HR was (P < 0.05) higher in pregnant than non-pregnant ewes during the different gestation phases. In conclusion, ambient temperature and gestation concomitantly modulate diurnal thermoregulatory responses of the ewes to hot-dry season. Adequate measures should be adopted to mitigate adverse impact of prolonged high RR on the dam and the foetus during the peak of ambient temperature prevailing in the tropical Savannah environment.