Effect of water restriction on physiological responses and certain reproductive traits of Malpura ewes in a semiarid tropical environment

Assessment of the adaptation of Nguni goats to water stress

The recurring drought and limited rainfall patterns occasioned primarily by climate change in sub-Saharan African countries threaten sustainable animal agriculture. The irreversibility of this natural phenomenon calls for an intensive and urgent selection of adaptable breeds that can cope but with minimal compromise on production indices. A water scarcity simulation study was conducted to assess the adaptation potential of Nguni goats to regulated watering by evaluating their growth performance, tolerance to heat and water stress and blood indices during the dry summer months. Eighteen growing Nguni goats (average age: 1 year; BW: 19.25 ± 1.6 kg) were assigned equally to three treatments: W0, without water restriction (WR); W70, WR of 70% ad libitum water intake (WI); and W50, WR of 50% ad libitum WI. The experimental trial lasted for 75 d following a 14-day acclimatisation to the housing condition. Data on growth performance, body thermal gradient, skin temperature (ST) and rectal temperatures, respiratory rate (RR), body condition scores (BCs), linear body indices and blood biochemical indices were taken. The results showed that the final BW was not affected (P > 0.05) by the water restriction levels. The daily gain, DM intake and total BW gain were similar (P > 0.05) in groups W70 and W50. Body thermal gradient and ST were not affected (P > 0.05). The RR and BCs decreased (P < 0.05) with increasing water restriction levels. The body and rump lengths and sternum height were similar (P > 0.05) for groups W70 and W50. There is an haemocentration (W0 < W70 < W50; P < 0.05) of sodium, Chloride, urea, creatinine, total protein, and cholesterol with water restriction levels. Generally, most physiological variables assayed were similar (P > 0.05) in the water-stressed groups (W70 and W50). Overall, Nguni goats showed an adaptive capacity to tolerate limited water intake.

Effect of reduced water intake on ovarian reserve, leptin immunoexpression and impact of leptin on the in vitro culture of sheep secondary follicles

This study evaluated the effect of reduced water intake on survival, apoptosis and immunoexpression of leptin in sheep preantral follicles, activation of primordial follicles, serum levels of leptin, estradiol (E2) and progesterone (P4), and in vitro maturation (IVM) of oocytes antral follicles, as well evaluated the effects of leptin on in vitro culture of secondary follicles isolated these animals. Ewes (n = 32) were divided into four groups: water ad libitum (Control - 100%), 80%; 60% and 40% of ad libitum intake. Blood was collected to determine, leptin, E2 and P4, before and after experiment. After the slaughter, ovarian cortex was used to histological and immunohistochemistry analysis and oocytes IVM. Moreover, isolated secondary follicles were cultured in vitro for 12 days in control medium (α-MEM+) or α-MEM+ with 10 or 25 ng/mL leptin. The reduction of water intake caused a linear decreasing effect on the percentages of normal preantral follicles, especially of primordial (P < 0.05), increased the apoptosis (P < 0.05) and decreased leptin expression in preantral follicles. The treatment with 60% of water intake showed greater total growth rate of isolated secondary follicles cultured with 25 ng/L leptin (P < 0.05), compared to those cultured in α-MEM+ . In conclusion, reduced water intake impaired the number of normal sheep preantral follicles, especially of primordial follicles, increased apoptosis and decreased leptin expression in preantral follicles. Moreover, secondary follicles from of ewes that receive 60% water intake increased follicular growth after in vitro culture with 25 ng/mL leptin.

Effects of Restricted Availability of Drinking Water on Blood Characteristics and Constituents in Dorper, Katahdin, and St. Croix Sheep from Different Regions of the USA

Different hair sheep breeds originated from diverse climatic regions of the USA may show varying adaptability to water deprivation. Therefore, the objective of this study was to assess the effects of restricted availability of drinking water on blood characteristics and constituent concentrations in different breeds of hair sheep from various regions the USA. For this study, 45 Dorper (initial age = 3.7 ± 0.34 yr), 45 Katahdin (3.9 ± 0.36 yr), and 44 St. Croix (2.7 ± 0.29 yr) sheep from 45 farms in 4 regions of the USA (Midwest, Northwest, Southeast, and central Texas) were used. Ad libitum water intake was determined during wk 2 of period one, with 75% of ad libitum water intake offered during wk 2 of period two, and 50% of ad libitum water intake offered for 5 wk (i.e., wk 5−9) in period three. Water was offered at 07:00 or 07:30 h, with blood samples collected at 08:00 and(or) 14:00 h in wk 1, 2, 3, 4, 8, and 9 for variables such as hemoglobin and oxygen saturation and wk 2, 4, 6, 8, and 9 for concentrations of glucose and other constituents. The blood oxygen concentration at 08:00 h was 4.86, 4.93, and 5.25 mmol/L in period one and 4.89, 4.81, and 5.74 mmol/L in period three for Dorper, Katahdin, and St. Croix, respectively (SEM = 0.160; p = 0.001). Blood oxygen at 14:00 h was 4.37, 4.61, and 4.74 mmol/L in period one and 4.66, 4.81, and 5.46 mmol/L in period three for Dorper, Katahdin, and St. Croix, respectively (SEM = 0.154; p = 0.003). St. Croix were able to maintain a higher (p < 0.001) blood oxygen concentration than Dorper and Katahdin regardless of water availability. The pattern of change in blood concentrations with advancing time varied considerably among constituents. However, concentrations of glucose (55.3 and 56.2 mg/dL; SEM = 0.84), lactate (24.1 and 22.5 mg/dL; SEM = 0.79), total protein (7.08 and 7.17 g/dL; SEM = 0.0781), and albumin (2.59 and 2.65 g/dL in wk 2 and 9, respectively; SEM = 0.029) were similar (p > 0.05) between periods one and three. Conversely, concentrations of cholesterol (56.2 and 69.3 mg/dL; SEM = 1.33) and triglycerides (28.6 and 34.5 mg/dL in wk 2 and 9, respectively; SEM = 0.98) were greater (p < 0.05) in period three vs. 1. In conclusion, water restriction altered almost all the blood variables depending upon severity and duration of restriction, but the hair sheep breeds used from different regions of the USA, especially St. Croix, displayed considerable capacity to adapt to limited drinking water availability.

Impacts of short-term water restriction on Pelibuey sheep: physiological and blood parameters

One of the projected effects of climate change is a reduction in rainfall in certain regions of the world. Hence, the agricultural and livestock sectors will have to cope with increasing incidences of water shortage while still maintaining productivity levels to feed an ever increasing global population. This short communication reports on the effect of a 2-week water stress on Pelibuey sheep in Cuba. Three treatments were compared, viz. supply of water ad libitum, water supplied once every 3 or 6 days. Following exposure to the water stress, the results showed no changes in sheep body weight or rectal temperature. However, respiration frequency was affected with water stress causing a reduction from 23.3 to 13.3 respirations per min in control and water-deprived animals, respectively. Furthermore, there was evidence for hemoconcentration in response to water stress (levels of hemoglobin increased from 9.2 to 13.1 g L^-1 and hematocrits from 27.6 to 39.3% in the control group and animals restricted to water once every 6 days. The imposed water stress was also evident in the reduction of lymphocytes (from ±63 to 43%), and in increase of neutrophils (from approximately 38 to 54%) and leukocytes (from 3133 to 4933 per mm³). The results indicated a decline in the levels of antioxidants, i.e., SOD from approximately 13 to 10 U mg^-1 protein and CAT activity from 23 to 9 U mg^-1 protein. To the best of our knowledge, this is the first report on the response of Pelibuey sheep to short-term water shortage stress under Cuban environmental conditions.

Effects of restricted availability of drinking water on body weight and feed intake by Dorper, Katahdin, and St. Croix sheep from different regions of the USA

Resilience to restricted availability of drinking water was evaluated with 44 Dorper (DOR; initial age = 3.7 ± 0.34 yr), 42 Katahdin (KAT; 3.9 ± 0.36 yr), and 42 St. Croix (STC; 2.7 ± 0.29 yr) sheep from 46 farms in 4 regions of the USA (Midwest, MW; Northwest, NW; Southeast, SE; central Texas, TX). Ad libitum water intake was determined during 2 wk of period 1, with 75% of this amount offered in 2 wk of period 2 and 50% in 5 wk (i.e., 5 to 9) of period 3. Body weight and DMI in week 2 of period 1 and week 9 of period 3 were analyzed with a mixed effects model. There was a breed × period interaction (P = 0.023) in water intake relative to BW (6.17, 6.69, and 7.19 in period 1 and 3.04%, 3.26%, and 3.36% BW in period 3 for DOR, KAT, and STC, respectively; SEM = 0.219). There were 3-way interactions of breed, region, and period in BW and DMI in g/d (P < 0.010). For STC, BW was greater (P < 0.05) in period 3 vs. 1 for all regions (50.1, 47.6, 42.4, and 45.8 kg in period 1 and 51.9, 49.3, 44.5, and 47.7 kg in period 3), whereas there was only a period difference for DOR from the MW and SE (61.4, 66.0, 64.6, and 59.6 kg in period 1 and 60.6, 66.5, 65.7, and 62.4 kg) and for KAT from TX (50.1, 47.6, 42.4, and 45.8 kg in period 1 and 51.9, 49.3, 44.5, and 47.7 kg in period 3 for MW, NW, SE, and TX, respectively; SEM = 2.57). In accordance, DMI by STC was similar (P > 0.05) between periods for all regions (1.25, 1.17, 1.06, and 1.16 kg/d in period 1 and 1.12, 1.08, 1.02, and 1.02 kg/d in period 3), as was also the case for DOR from MW and SE but not from NW or TX (1.54, 1.50, 1.30, and 1.41 kg/d in period 1 and 1.41, 1.13, 1.25, and 1.18 kg/d in period 3) and KAT from TX though not from the other 3 regions (1.47, 1.52, 1.48, and 1.40 kg/d in period 1 and 1.06, 1.15, 1.30, and 1.33 kg/d in period 3 for MW, NW, SE, and TX, respectively; SEM = 0.061). In conclusion, based on BW and DMI with water intake restricted at 50% of ad libitum consumption by individual animals, STC appeared more consistent in display of high resilience to restricted water availability, although DOR from 2 regions and KAT from 1 also were relatively resilient. The results suggest benefit to breed comparisons of inclusion of animals from multiple areas and that environmental conditions of regions may have disparate effects with different breeds of hair sheep.

Small Ruminants: Farmers' Hope in a World Threatened by Water Scarcity

Simple Summary

Water is one of the most important nutrients to livestock. It is so essential that more than half the volume of the animal's body is water. However, its availability is threatened by the irreversible changes in climate, which has culminated into reduced rainfall in most regions of the world. Such an increasing threat to regular water supply, and by extension to food security and livelihood has forced a shift from large to small ruminant production, especially in regions experiencing low rainfall, with farmers taking advantage of their adaptive process and efficiency of water use. Small ruminants, especially desert goats, can adaptively survive in water-limited areas while trekking long distance in search of feed and they will regain any weight loss at the next watering point. Further research is needed on adaptive indigenous breeds of small ruminants since tolerance to water scarcity is breed dependent, so that improvements can be made through effective selection and breeding program.

Abstract

The availability and sustainability of suitable and good quality drinking water is a global concern. Such uncertainties threaten livestock production with an attendant ripple effect on food security. Small ruminants, including sheep and goats, appear to be promising to smallholder farmers in solving this problem because of their ability to survive in water-limited areas and harsh environment when compared with large ruminants. Their small body size is also seen as an advantage, because less water will be required for proper digestion and feed utilization. Therefore, this review will provide information regarding the adaptive responses of small ruminants on thermoregulation, blood metabolites, immune status, drug pharmacokinetics, reproduction and hormonal indices during the period of water stress. Adaptable and indigenous breeds are known to be more tolerant to water stress than selected breeds. A drop in feed intake and weight reduced respiratory rate and increased concentration of blood metabolites are the general effects and/or observations that are encountered by small ruminants during the period of water stress. The concept of water tolerance either as deprivation and/or restriction of indigenous and adaptable breeds of small ruminants is gaining ground in research studies around the world. However, more research, however, seeking to explore water tolerance capacity of adaptable breeds especially in arid and water limiting areas are still needed.

Renal efficiency underlies adaptive heterothermy of heat-stressed hypohydrated goats

We investigated the thermotolerance of the F1 progeny (Black Bedouin × Damascus crossbreed) to summer conditions alongside that of two pure breeds. Male goats (n = 7 per breed) were used to conduct a summertime 28-day trial along with hypohydration. The animals were fitted with miniscule thermologgers, intraperitoneally and subcutaneously, to measure core (T_c) and peripheral (T_p) body temperatures (BT), respectively. All goats were kept under shaded housing for a 7-day basal period before being switched to unshaded pens for the next 21 days. During the first 14 days, animals had free access to water. However, during the third 7-day period, access to water was time-restricted (4 h/day). Finally, it was restricted to 40% of the third week's average daily intake over the last 7 days. Exposure to the unshaded conditions resulted in pronounced heat stress in all animals, as reflected by 0.42 and 1.44 °C rises for T_c and T_p, respectively. The F1 goats displayed a clear heterothermic adaptive response, especially after the water restriction bouts' initiation. Interestingly, the F1 goats displayed higher ratios of renal relative medullary thickness (77.7, 73.3, and 72.6 ± 1.1%) along with higher circulating concentrations of antidiuretic hormone (44.6, 31.6, and 11.6 ± 3.7 ng/mL), respectively, which suggested an improved water metabolism.

Effect of water restriction on milk yield and quality in Lacaune breed ewes

The effect of water restriction on body weight, body condition score, milk yield, and milk composition and rheological characteristics in intensively reared Lacaune ewes was evaluated. After 7 days of adaptation, the trial lasted 28 days. Thirty lactating ewes (48 ± 5 months of age; mean value ± standard deviation) at the beginning of third lactation month were divided into three groups (n = 10), corresponding to the following water restriction treatment: a group control received no drinking water restriction (W100), and two groups received water to the extent of 80% and 60% of W100 daily consumption (W80 and W60 group respectively). The effects of water restriction were assessed at the beginning of experiment (D0), at D14 and D28. The W60 group resulted in a significant decrease in body weight, body condition score, milk yield and feed consumption of hay due to the experimental treatment; whereas a marked increase in both W60 and W80 groups of milk lactose, urea, sodium, sodium chloride content and titratable acidity was observed. Rheological parameters of milk, rennet coagulation time and curd-firming time were positively affected by water restriction treatments, with a decrease in both experimental groups of the time required for the formation of a stable and firm curd. Results highlight the importance of water consumption in dairy sheep. The scarce availability of water, significantly affecting ewes milk production, is worthy of particular attention in arid area where water stress-resistant breeds should be considered. This study underlines that milk yield, being closely linked to the availability of water of the breeding habitat due to its high water content (about 81%), could be reached in area where water is not a limiting factor without reducing the genetic expression of the animals. Less severe water restrictions, such as 20% of daily voluntary water intake, produce no detrimental effect on milk yield.