Metabolic and endocrine responses to cold and feed restriction in ruminants

Effects of different winter paddock management of Thoroughbred weanlings and yearlings in the cold region of Japan on physiological function, endocrine function and growth

Effects of different winter paddock management of Thoroughbred weanlings and yearlings in Hokkaido, Japan, which is extremely cold in winter, on physiological function, endocrine function and growth were investigated. They were divided into two groups; those kept outdoors for 22 hr in the paddock (22hr group) and those kept outdoors for 7 hr in daytime with walking exercise for 1 hr using the horse-walker (7hr+W group), and the changes in daily distance travelled, body temperature (BT), heart rate (HR), HR variability (HRV), endocrine function and growth parameters were compared between the two groups from November at the year of birth to January at 1 year of age. The 7hr+W group could travel almost the same distance as the 22hr group by using the horse-walker. The 22hr group had a lower rate of increase in body weight than the 7hr+W group in January. In addition, lower in BT and HR were observed, and HRV analysis showed an increase in high frequency power spectral density, indicating that parasympathetic nervous activity was dominant. And also, changes in circulating cortisol and thyroxine were not observed despite cold environment. On the other hand, the 7hr+W group had higher prolactin and insulin like growth factor than the 22hr group in January, and cortisol and thyroxine were also increased. Physiological and endocrinological findings from the present study indicate that the management of the 7hr+W group is effective in promoting growth and maintaining metabolism during the winter season.

Supplementary Feed Additives Can Improve Lamb Performance in Terms of Birth Weight, Body Size, and Survival Rate

To evaluate the effects of supplementation of feed additives in the last trimester of pregnancy on placental characteristics and offspring performance, this study was conducted with 48 estrous-synchronized Ghezel ewes that had randomly been assigned to one of the following six groups (n = 8): ad libitum feeding (AL); feed restriction (RF; 60% of ad libitum intake); feed restriction + propylene glycol (PG); feed restriction + propylene glycol + monensin sodium (MS); feed restriction + propylene glycol + rumen-protected choline chloride (RPC); feed restriction + propylene glycol + monensin sodium + rumen-protected choline chloride (PMC). Birth weight, body size, and rectal temperature of lambs were determined within 24 h of birth. The presence of lambs at 87 days of age was used as an index of survival to weaning. The outcome of this study was that the average placental weight of ewes in the AL and MS groups was the highest and lowest, respectively, among the treatment groups (p < 0.01). RPC ewes presented higher placental efficiency compared to AL, RF, and MS ewes (p < 0.05). The largest and smallest crown-to-rump lengths (CRLs) were observed in PMC and RF lambs, respectively (p < 0.01). In addition, lambs born from PMC, RPC, and PG ewes had a longer curved crown-to-rump length (CCRL) than those born from AL and RF ewes (p < 0.01). The concurrent administration of propylene glycol and rumen-protected choline chloride resulted in the highest birth weight among treatment groups (p < 0.01). Lambs born to PMC and RPC ewes had a higher survival rate and rectal temperature than those born to RF ewes (p < 0.05). It can be concluded that although dietary restriction does not have adverse effects on lambs’ performance compared with ad libitum intake, the combined administration of propylene glycol and rumen-protected choline chloride in the ewes’ restricted diet can improve placental characteristics and subsequently amend lambs’ birth weight and body size. Therefore, the combined administration of these additives can be practiced during feed restriction.

Influence of refeeding on production, blood biochemistry parameters, and reproduction in underfed Kacang goat does

This research aimed to investigate the effect of refeeding on production, blood biochemical parameters, and reproduction in underfed Kacang goat does. Twelve 2-3-year-old Kacang goats scored (body condition score [BCS]: 1-1.5) with poor body condition but appeared healthy, gave normal births 3-4 months before but no longer nursing their youngs, and anestrus were used in this study. The experiment consisted of 110 days with 14 days of adaptation period and 96 days of feeding treatment and data collection. After the adaptation period, the animals were divided into two groups (A and B), with six animals each. During the first 40 days (underfeeding period), they were fed with kangkong (Ipomoea reptans) straw at a level of 2% of body weight (BW). For the following 56 days (refeeding period), each animal in group A was fed at the level of 4% BW per day while group B was fed at the level of 5% BW per day consisting of 50% kangkong straw and 50% concentrate. Feed intake, average daily gain, body condition, and estrus were assessed in the period of underfeeding and refeeding. Blood samples were collected at the end of the underfeeding and refeeding period for blood biochemical parameter analyses. During the underfeeding period, the animals were anestrous and had poor body condition (BCS: 1.17-1.33) and high serum levels of cortisol, progesterone, and estradiol. Refeeding resulted in a significant increase in BCS (2.75-3.0), restoring estrous cycle, and reduced serum cortisol and progesterone level (p < 0.05). The Kacang goats had good compensatory growth. It could be concluded that refeeding at the level of 4-5% BW would restore undernourished goats' clinical condition, productivity, and reproductive performance after 8 weeks of refeeding.

Elliptical and linear relationships with rumen temperature support a homeorhetic trajectory for DMI during recovery of feedlot cattle exposed to moderate heat load

Most feedlot animals in Australia experience 2 to 3 moderate heat waves during summer. This study aimed to gain understanding of the physiological drivers in response to and during recovery from such events with a view to designing strategies to ensure rapid and safe recovery. Two hypotheses were tested during thermal challenge and recovery in climate-controlled rooms (CCR): firstly, the feedlot steer on a grain-based diet mounts appropriate physiological responses during moderate heat load and in recovery so that its performance and physiology state after recovery is not different to the feed restricted thermoneutral (FRTN) steer. Secondly, commonly used indicators of increased heat load, e.g., respiration rate (RR), panting score (PS), body surface temperatures (ST), and water consumption (WC), reflect rumen temperature (RT) during thermal challenge and recovery at the level of daily means. In this study, 36 Angus steers (live weight (LW) 451.5 ± 22.6 kg) made up 3 cohorts of 12 animals that sequentially underwent the CCR phase. For this 18-d phase, the steers were allocated to either a moderate heat load treatment (thermally challenged, TC, n = 18) or a FRTN treatment (n = 18). The TC group underwent 3 periods, Pre-Challenge (4 d, temperature humidity index (THI) range of 68 to 71), Challenge (7 d, THI 73 to 84 with diurnal cycling), and Recovery (7 d, THI 68 to 71). The FRTN group were held at thermoneutral conditions in the CCR (THI 66.9 ± 0.3), and each animal was offered an amount of feed was based on the feed intake of its LW matched TC pair. Thus, as DMI fell in the TC group during Challenge, feed restriction was imposed on the FRTN group. The data were collected by trained observers were DMI, RT, RR, PS, body STs (forehead, shoulder, leg, rump), and WC. Challenge induced a heat stress response in the TC group with reduced DMI and LW, and elevated RT, RR, PS, body STs, and WC (P < 0.001). These measures were unchanged or reduced in the FRTN group (P < 0.001). At the end of Recovery, the TC and FRTN groups had converged on most measures including LW. Daily mean RT of both groups showed strong linear relationships with THI, RR, PS, head ST, and WC (P ≤ 0.0022) but opposing elliptical relationships with DMI; that is, as DMI fell with increasing RT for the TC group, DMI increased with rising RT for the FRTN group. In all, the feedlot steers in this study demonstrated sufficient homeorhetic capacity to adjust to moderate heat load and recover from it.

Effect of air temperature on growth performance, apparent digestibilities, rumen fermentation and serum metabolites in Altay and Hu lambs

Fat-tailed Altay sheep are indigenous to the Altay prefecture and well adapted to severe cold and sparse pasture of poor quality. Hu sheep were introduced to this region in the 1970s and are raised mainly in feedlots. We hypothesized that the dietary energy utilization would differ between breeds and predicted that Altay sheep would be more efficient than Hu sheep, in particular at a low air temperature. To test this prediction, we examined growth performance, apparent digestibilities, rumen fermentation and serum metabolites in Altay (32 ± 2.6 kg) and Hu sheep (31 ± 2.7 kg) at air temperatures of -5 and 20°C. Average daily gain (ADG), feed and metabolizable energy intakes were greater in Altay than in Hu sheep (p < .01), and all were greater at -5°C than 20°C (p < .01). Body mass gain-to-feed intake ratio was higher in Altay than in Hu sheep (p < .001), but was not affected by air temperature (p > .10). Rumen total volatile fatty acid (VFA) concentration was greater in Hu than in Altay sheep (p < .05) and was greater at 20°C than at -5°C (p < .05), while rumen microbial protein concentration was greater in Altay than in Hu sheep (p < .05). Rectal temperature was higher at -5°C than 20°C (p < .05) and was similar between breeds (p > .05). Serum glucose, non-esterified fatty acid (NEFA) and urea-N concentrations were higher in Hu than in Altay sheep (p < .05). It was concluded that Altay sheep are better able to cope with poor quality diets as they had higher digestibility of nutrients, ADG and body mass gain-to-feed intake ratio than Hu sheep.

Rno-miR-425-5p targets the DLST and SLC16A1 genes to reduce liver damage caused by excessive energy mobilization under cold stress

MicroRNAs (miRNAs) are a class of single-stranded non-coding small RNA molecules, which participate in the regulation of many physiological processes, and play a crucial role in cancer, metabolism and other processes. Rno-miR-425-5p has been shown to play a role in the response to cold stress. To explore the mechanism by which rno-miR-425-5p regulates the response to cold stress, we analysed the candidate target genes of rno-miR-425-5p. After verification in rat hepatocyte BRL cells and in rat liver tissue, we identified several target genes that were altered in expression in response to cold stress. In rat liver tissue, the expression of rno-miR-425-5p was significantly increased and the expression levels of target genes DLST and SLC16A1 were decreased under cold stress. The miRNA and mRNA levels were analysed by quantitative real-time PCR and the protein levels were detected by Western blot analysis. Combined with the results of bioinformatic analysis, we concluded that rno-miR-425-5p reduced the expression of DLST and SLC16A1, inhibiting energy release from the tricarboxylic acid cycle and preventing the liver from being injured by excessive energy mobilization.

The effect of plane of nutrition and shearing on the pattern of the moult in Scottish Cashmere goats

The effect of plane of nutrition on the timing of the moult in cashmere goats was investigated. Three groups of mature does were individually offered food to supply 0·8 (L, no. = 14), 1·2 (M, no. = 14) or 20 (H, no. = 13) times their estimated maintenance energy requirements from mid December until mid May. Two other groups of goats which were shorn in mid January, were offered 1·2 times maintenance requirements from mid December until mid March when food levels were increased to either 1·6 M (SL, no. = 6) or ad libitum (SAL, no. = 6). In mid May mean live weights for treatments L, M, H, SL and SAL were 36·0, 41·5, 46·9, 33·0 and 43·1 kg (average s.e.d. = 2·27, P < 0·001).

The pattern of moult was described by changes in a subjectively assessed moult score, the proportion of follicles with brushes and staple length. The loss of brushes, indicating the start of the moult, began from the primary follicles on days 143, 131, 76, 150 and 129 (average s.e.d. = 13·5, P < 0001), and from the secondary follicles on days 141, 128, 104, 144 and 125 (average s.e.d. = 14·1, P = 0·053) for treatments L, M, H, SL and SAL respectively. The loss of brushes from primary and secondary follicles was completed on average, by days 194 and 206 of the experiment respectively, and there were no differences between treatments. Moult score and staple length data confirmed the conclusion that lowering the plane of nutrition delayed the start of the moult. No additional effect of fleece removal in the shorn treatments was observed.

Changes in circulating levels of plasma prolactin, thyroxine, tri-iodothyronine, insulin, insulin-like growth factor-1 and growth hormone were related to seasonal changes in daylength and plane of nutrition. Their rôle in the control of the moult is discussed.

Manipulation of the nutrition of cashmere goats in early spring has the potential to delay and increase the synchrony of fibre moult and to improve the efficiency of cashmere harvesting.

Effects of pre-slaughter diet/management system and fasting period on physiological indicators and meat quality traits of lambs

This study determined the effects of pre-slaughter diet/management system on blood and rumen parameters and meat-quality traits of Norduz lambs. Eighty lambs were divided into two groups according to diet (AH: alfalfa hay; BAH: alfalfa supplemented with 500 g/head barley) for 21 days. Following this period, lambs from each group were distributed among four groups according to pre-slaughter fasting period as 0, 12, 24 or 48 h. Cortisol concentrations were found to be significantly higher in the 24 h and 48 h groups when compared to the 0 h group (p<0.01). Diet and fasting period had limited effect on muscle glycogen content and ultimate pH·L*, WHC and moisture decreased in line with increases in the fasting period (p<0.01). In conclusion, carcass conformation and some meat quality traits were better in BAH lambs. Fasting had a negative effect on some meat quality parameters, with significant increases in some physiological stress indicators after fasting periods of 24 h or longer.

Thyroid hormones correlate with field metabolic rate in ponies, Equus ferus caballus

During winter free living herbivores are often exposed to reduced energy supply at the same time that energy needs for thermoregulation increase. Several wild herbivores as well as robust horse breeds reduce their metabolism during times of low ambient temperature and food shortage. Thyroid hormones (TH) affect metabolic intensity and a positive effect of TH on basal metabolic rate (BMR) has been demonstrated in mammals and birds. As BMR and field metabolic rate (FMR) are often assumed to be intrinsically linked, TH may represent a reliable indicator for FMR. To test this hypothesis, ten Shetland pony mares were kept under semi-extensive central European conditions. During the winter month one group was fed 60% and one group 100% of their maintenance energy requirements. We measured FMR, locomotor activity, resting heart rate and TH levels in summer and winter. FMR, locomotor activity, resting heart rate and total T3 concentrations decreased substantially in winter compared to summer, whereas total T4 increased. Feed restriction led to a reduced FMR and resting heart rate, while TH and locomotor activity were not affected. Across both seasons FMR, resting heart and locomotor activity were positively correlated with total T3 but negatively and more weakly related with total T4.

Effects of weaning on total and free iodothyronines in lambs

BACKGROUND

Weaning is a crucial period in the management of lambs, resulting in physiological and mental challenges, that may have prolonged effects on lamb's health and welfare.

HYPOTHESIS/OBJECTIVES

To evaluate the effect of weaning on total and free triiodothyronine (T3, fT3) and thyroxine (T4, fT4) concentrations in serum of lambs by enzyme immunoassay. Animal and methods: The study was performed on two groups of 17 clinically healthy Comisana cross-bred lambs (7 males and 10 females) with or without weaning at 10 weeks of age. Serum samples were collected at the age of 8 weeks, 24 h and 2 weeks after weaning in the experimental group and at similar times in the non-weaned control group. Enzyme immunoassay was performed. Statistical analysis was done by one-way analysis of variance.

RESULTS

Compared to control animals, weaned animals showed significantly decreased T3 and elevated T4 concentrations two weeks after weaning with higher concentrations in both males and females in contrast to 24 h after weaning. Body weight (BW) was significantly restored in both females (11% increase) and males (6%) two weeks after weaning as compared to 24 h after weaning. No gender effects were shown for total and free iodothyronine changes. Significant positive correlations were observed between BW and T4 concentrations in both females (r = 0.692) and males (r = 0.856), fT3 concentrations in males (r = 0.968) and fT4 concentrations in females (r = 0.862).

CONCLUSION AND CLINICAL IMPORTANCE

Total iodothyronines could represent an indicator of their different metabolic activity with their magnitude altered two weeks following weaning.

Effect of Varying the Energy Density of Protein-adequate Diets on Nutrient Metabolism, Clinical Chemistry, Immune Response and Growth of Muzaffarnagari Lambs

Effects of varied dietary energy densities on immune response and performance of Muzzafarnagari lambs were ascertained in a 180-d study. Animals (n = 24), in three groups, were fed diets providing 100% (100E), 80% (80E) or 70% (70E) of their metabolizable energy requirement. Mean nutrient digestibilities varied significantly among treatments. Nitrogen intake was lower (p<0.01) in the 70E. Nitrogen retention, was reduced (p<0.001) in 80E and 70E vs 100E. The average daily gain (p<0.001) was 47.01±4.23, 13.54±1.72 and -16.67±8.24 g for 100E, 80E and 70E, respectively. Hemoglobin concentration, haematocrit, total and differential leukocyte counts were lower (p<0.001) for 80E and 70E than for 100E with a similar trend (p<0.05) for serum glucose and total protein. Serum cortisol was reduced (p<0.001) with decreased energy availability. Antibody titre to Brucella abortus S19 showed an initial reduction in 80E and 70E vs 100E. Delayed-type hypersensitivity response was lower (p<0.001) in 80E and 70E vs 100E, accompanying a lower (p<0.001) nitric oxide production by the peripheral lymphocytes. It is concluded that the reduced dietary energy density significantly affects the growth performance and immune response of lambs.

Impact of prolonged cold exposure on dry matter intake and enteric methane emissions of beef cows overwintered on low-quality forage diets with and without supplemented wheat and corn dried distillers’ grain with solubles

Bernier, J. N., Undi, M., Plaizier, J. C., Wittenberg, K. M., Donohoe, G. R. and Ominski, K. H. 2012. Impact of prolonged cold exposure on dry matter intake and enteric methane emissions of beef cows overwintered on low-quality forage diets with and without supplemented wheat and corn dried distillers’ grain with solubles. Can. J. Anim. Sci. 92: 493–500. This study was conducted to determine the impact of prolonged cold exposure on dry matter intake (DMI) and enteric methane (CH4) emissions of overwintering beef cows consuming low-quality forage with and without supplemented protein in the form of dried distillers’ grain with solubles (DDGS). The study was carried out with 30 mature, dry, open beef cows (663±52.9 kg) that were fed a low-quality (deficient CP, 6.0% CP) forage (control), low-quality forage supplemented with 10% DDGS (sufficient CP, 8.7% CP; DDGS10) or 20% DDGS (excess CP, 11.6% CP; DDGS20). Carrying out the study from October through February allowed assessment under thermal neutral and prolonged cold conditions typical of the prairie region of Canada (Manitoba, Alberta and Saskatchewan). Average minimum and maximum daily temperatures were 2.7 and 13.8°C in the thermal neutral period, and –23.5 and −11.0°C in the prolonged cold period, respectively. When no protein supplements were offered, cows exposed to prolonged cold consumed less (P=0.01) forage than when exposed to thermal neutral conditions. Enteric CH4 emissions, when measured as litres per day, were not influenced (P>0.05) by dietary protein supplementation, averaging 285.6±11.71, 311.9±11.49 and 282.6±13.02 L d−1 for cows fed control, DDGS10, and DDGS20 diets, respectively. When expressed as a percentage of energy consumed, cows consuming low-quality forage supplemented with 20% DDGS produced 18.5% less (P=0.01) enteric CH4 relative to cows consuming the low-quality forage only, with emissions of 5.3±0.38 and 6.5±0.33% GEI, respectively. Mature beef cows maintained at the same physiological status and dietary regime produced 26.8% less (P=0.001) enteric CH4 (7.1±0.30 vs. 5.2±0.26% GEI) under prolonged cold as compared with thermal neutral conditions. Based on these results, enteric CH4 emissions for the Canadian cow herd that is overwintered outdoors may be overestimated using current International Panel on Climate Change (IPCC) methodology.

Reduced cortisol and metabolic responses of thin ewes to an acute cold challenge in mid-pregnancy: implications for animal physiology and welfare

BACKGROUND

Low food availability leading to reductions in Body Condition Score (BCS; 0 indicates emaciation and 5 obesity) in sheep often coincides with low temperatures associated with the onset of winter in New Zealand. The ability to adapt to reductions in environmental temperature may be impaired in animals with low BCS, in particular during pregnancy when metabolic demand is higher. Here we assess whether BCS affects a pregnant animal's ability to cope with cold challenges.

METHODS

Eighteen pregnant ewes with a BCS of 2.7±0.1 were fed to attain low (LBC: BCS2.3±0.1), medium (MBC: BCS3.2±0.2) or high BCS (HBC: BCS3.6±0.2). Shorn ewes were exposed to a 6-h acute cold challenge in a climate-controlled room (wet and windy conditions, 4.4±0.1°C) in mid-pregnancy. Blood samples were collected during the BCS change phase, acute cold challenge and recovery phase.

RESULTS

During the BCS change phase, plasma glucose and leptin concentrations declined while free fatty acids (FFA) increased in LBC compared to MBC (P<0.01, P<0.01 and P<0.05, respectively) and HBC ewes (P<0.05, P<0.01 and P<0.01, respectively). During the cold challenge, plasma cortisol concentrations were lower in LBC than MBC (P<0.05) and HBC ewes (P<0.05), and FFA and insulin concentrations were lower in LBC than HBC ewes (P<0.05 and P<0.001, respectively). Leptin concentrations declined in MBC and HBC ewes while remaining unchanged in LBC ewes (P<0.01). Glucose concentrations and internal body temperature (T(core)) increased in all treatments, although peak T(core) tended to be higher in HBC ewes (P<0.1). During the recovery phase, T4 concentrations were lower in LBC ewes (P<0.05).

CONCLUSION

Even though all ewes were able to increase T(core) and mobilize glucose, low BCS animals had considerably reduced cortisol and metabolic responses to a cold challenge in mid-pregnancy, suggesting that their ability to adapt to cold challenges through some of the expected pathways was reduced.

Assessment of welfare from physiological and behavioural responses of New Zealand dairy cows exposed to cold and wet conditions

There is a need to assess the welfare of dairy cows that live outdoors under cold and wet conditions. This study combined a number of techniques to measure stress and make an assessment of welfare in this situation. Two groups of ten non-pregnant, non-lactating Holstein Friesian cows were exposed to a week of wind and rain (WR) or housed indoors (I) with pre- and post-treatment weeks indoors in a cross-over design. Wind and rain consisted of continual air movement (7.1 kph) using fans, water sprinkling for 15 min (3.0 mm) per hour, a mean temperature of 3.4°C and wind chill of –0.3°C. Internal body temperature was recorded every ten min and behaviour for 16 h per day. Blood, faeces and infrared temperatures were sampled at 0800h each morning during treatment weeks, and three times per week during pre- and post-treatment weeks. All cows were challenged with 2 ml Leptoshield Vaccine (CSL Animal Health, Australia) subcutaneously after 3 days of cold exposure to test immune responses. During WR, cows spent a greater proportion of time standing and less time lying down and eating than during I. Infrared temperatures were lower during WR than I in both dorsal and orbital (eye) regions. There was a distinct diurnal pattern of internal body temperature which had a greater amplitude during WR than I resulting from both a lower minimum and a higher maximum. The time of the minimum was 40 min later for WR than I. The overall mean body temperature was 0.07°C higher in WR than I. There were greater increases in plasma and faecal cortisol during WR than I, respectively. Total T4 was higher during WR than I. Non-esterified fatty acid concentration was higher in the week following WR than I. Total white blood cell numbers were lower during WR than I. No treatment differences were found for creatine kinase or for tumour necrosis factor, heat shock protein 90, interleukin 6 or interferon gamma expression in response to vaccination. In conclusion, this study applied a suite of stress measures to dairy cows exposed to extreme cold and wet conditions. Together, these measures indicated activation of the stress axis, physiological and behavioural adaptations to cold and a reduction in welfare. A number of these measures could be used to assess welfare under cold conditions on farms.