Changes in concentrations of plasma metabolites and insulin-like growth factor-1 after feeding in Japanese Black and Japanese Shorthorn cattle

The aim was to characterize the changes of plasma component concentrations after feeding in Japanese Black (B) and Japanese Shorthorn (S) cattle. Eight females, five B and three S, with a mean bodyweight (standard deviation) of 282.0 (20.3) kg were selected and supplied with only water for 28 h after feeding. Blood was taken from the jugular vein at 4‐h intervals for 32 h after feeding. Metabolite (cholesterol, CL; glucose, GLU; nonesterified fatty acid, NEFA; triacylglycerol, TG; total protein, TP) and insulin‐like growth factor‐1 (IGF‐1) concentrations in plasma were measured. In both breeds GLU tended to decrease linearly with a similar slope. Differences between the initial mean NEFA at 4 h after feeding (Start) and that at 24 h after the start (End) were significant in both breeds, but S increased significantly more than B at and after 8 h from the Start. The TG in S tended to change more than in B, and CL and IGF‐1 in both breeds changed continuously at similar levels. The TP in B tended to decrease more slowly and be lower than S. The change in NEFA, especially, suggests that nutritional status sensitively reflects genetic background.     

Selected Metabolic and Hormonal Profiles during Maintenance of Spontaneous Ovarian Cysts in Dairy Cows

Information is lacking regarding the relationship between metabolic and hormonal profiles and the maintenance of spontaneous ovarian cyst disease in dairy cows. For this reason, the concentrations of non‐esterified fatty acids (NEFA), insulin‐like growth factor I (IGF‐I) and cortisol (C) were investigated during the spontaneous course of ovarian cyst disease in dairy cows (n = 6) between the 7th and 16th weeks post‐partum (PP). The control group consisted of normally cycling cows (n = 6). Blood samples were collected twice a day, and plasma was analysed using different techniques. Progesterone and 15‐ketodihydro‐PGF_2α plasma profiles were investigated to confirm the ovulatory or anovulatory conditions of the cows. Cortisol plasma levels were not significantly different among sampling times within each group or between the two groups. NEFA plasma levels were significantly higher in cycling cows compared to cystic cows at the 16th week PP (p < 0.01), but with rather low values, indicating by now sparse mobilization of fat stores. Insulin‐like growth factor I plasma concentrations were higher in cystic cows during the 8th, 10th, 11th (p < 0.01) and 16th week PP (p < 0.05), indicating that the presence of ovarian cysts coincides with increased IGF‐I levels. These results suggest no influence of cortisol and NEFA levels in cysts maintenance, while a possible involvement of IGF‐I can be suspected not only in the pathogenesis, as already known, but also in the maintenance of spontaneous cystic ovarian disease in cattle.     

Leptin, GH, PRL, Insulin and Metabolic Parameters Throughout the Dry Period and Lactation in Dairy Cows

Leptin may play a role in the endocrine-metabolic processes that guarantee the physiological course of lactation in dairy cattle. This study was aimed at determining the changes in plasma concentrations of leptin and some of the main hormones and metabolites involved in the lactogenetic process in high-yielding dairy cows throughout lactation; we also wanted to assess whether leptin secretion is subjected to seasonal influences. Blood samples were collected from 23 Italian Friesian dairy cows from the end of a lactation to the ninth month of the subsequent one; in addition, blood was sampled from 47 dairy cows in different phases of lactation during February and July. Plasma concentrations of leptin, growth hormone (GH), insulin, prolactin (PRL), glucose, non-esterified fatty acids (NEFA) and urea were quantified by either validated radioimmunoassay (RIA) or enzymatic colorimetric methods. At the beginning of lactation, GH concentrations significantly increased, while a significant reduction occurred in leptin and insulin. This endocrine condition, such as the significant increase in NEFA plasma concentrations, is indicative of a marked lipid mobilization. In the more advanced stages of lactation, when both energy and protein balances become positive, leptin plasma concentrations increased, whereas GH and NEFA concentrations declined. During the summer months, a significant increase in leptin plasma concentrations, irrespective of the phase of lactation, was observed. Collectively, our findings suggest that, in dairy cows, leptin may represent a 'metabolic signal' of animal's status of fattening and nutritional level; in addition, leptin seems to be influenced by photoperiod and environmental temperature.     

Metabolic and luteal function in winter‐calving Spanish beef cows as affected by calf management and breed

This experiment aimed at evaluating the effect of calf management and breed on the metabolic and luteal function of post‐partum beef cows fed at maintenance. Fifty multiparous cows, 22 Parda de Montaña (PA) and 28 Pirenaica (PI), were assigned to either suckling once‐daily for 30 min (RESTR) or ad libitum (ADLIB) from the day after calving. Blood samples were collected to analyse metabolites [non‐esterified fatty acids (NEFA), β‐hydroxybutyrate, total protein and urea)], insulin‐like growth factor‐I (IGF‐I) and progesterone (P4) at different intervals. Cows from RESTR maintained their live‐weight (LW) over the first 3 months post‐partum, whereas ADLIB cows lost nearly 4% LW. Both genotypes showed similar LW gains during this period (p > 0.10). Calf daily gains were lower in RESTR than in ADLIB treatment (p < 0.05), but similar across breeds (p > 0.10). Milk and lactose production were lower in RESTR cows than in ADLIB (p < 0.05). Milk and protein yield were greater in PA than in PI breed (p < 0.05). Serum NEFA, total protein and urea were higher in PI cows suckling ADLIB than in the rest (p < 0.05). Cows from PI breed had greater NEFA values than PA ones on the first week post‐partum (p < 0.001). Circulating IGF‐I was not affected by suckling frequency, breed nor their interaction (p > 0.10). Suckling frequency, but not breed, affected the interval from calving to first ovulation (p < 0.001), being shorter in RESTR than in ADLIB cows. In conclusion, the ad libitum suckling practice improved cow milk yield and offspring gain compared to once‐daily suckling for 30 min from the day after calving, at the expense of impairing the onset of cyclicity. The effect of calf management was confounded with breed on the studied blood biochemical constituents, but any of these metabolites influenced the role of endocrine IGF‐I in these genotypes.     

Effects of body condition score at parturition and postpartum supplemental fat on metabolite and hormone concentrations of beef cows and their suckling calves

To determine the effects of BCS at parturition and postpartum lipid supplementation on blood metabolite and hormone concentrations, 3-yr-old Angus x Gelbvieh beef cows, which were nutritionally managed to achieve a BCS of 4 +/- 0.07 (479.3 +/- 36.3 kg of BW) or 6 +/- 0.07 (579.6 +/- 53.1 kg of BW) at parturition, were used in a 2-yr experiment (n = 36/yr). Beginning at 3 d postpartum, cows within each BCS were assigned randomly to be fed hay and a low-fat control supplement or lipid supplements with either cracked high-linoleate or high-oleate safflower seeds until d 61 of lactation. The diets were formulated to be isonitrogenous and isocaloric, and the safflower seed supplements were formulated to achieve 5% DMI as fat. On d 31 and 61 of lactation, blood samples were collected preprandially and then hourly postprandially (at 0, 1, 2, 3, and 4 h). Serum insulin (P = 0.27) and glucose (P = 0.64) were not affected by BCS at parturition. The mean concentrations of plasma NEFA (P = 0.08) and beta-hydroxybutyrate (P = 0.08) tended to be greater, and serum IGF-I was greater (P < 0.001) in BCS 6 than BCS 4 cows. Conversely, serum GH was greater (P = 0.003) for BCS 4 cows, indicating that regulation of IGF by GH may have been uncoupled in BCS 4 cows. The postpartum diet did not affect NEFA (P = 0.94), glucose (P = 0.15), IGF-I (P = 0.33), or GH (P = 0.62) concentrations. Oleate-supplemented cows had greater (P = 0.03) serum insulin concentrations, whereas control cows had greater (P = 0.01) plasma beta-hydroxybutyrate concentrations. Concentrations of NEFA (P = 0.05) and glucose (P < 0.001) were greater, and beta-hydroxybutyrate tended (P = 0.07), to be greater at d 3, whereas serum IGF-I was greater (P = 0.003) at d 6 of lactation. Similar concentrations of NEFA, glucose, GH, and IGF-I indicate that the nutritional status of beef cows during early lactation was not influenced by lipid supplementation. However, perturbations of the somatotropic axis in BCS 4 cows indicate that the influence of energy balance and BCS of the cow at parturition on postpartum performance should be considered when making managerial decisions.     

Endocrine profiles of cows undergoing extended lactation in relation to the control of lactation persistency

We conducted an experiment in dairy cows investigating the effects of calving season, milking frequency and nutrition on lactation persistency. Cows calved in the Spring (n=12) or Winter (n=12). Commencing in lactation week 9 one udder-half of each cow was milked thrice-daily and half of each calving group received additional concentrate at a fixed rate of 3kg per day above that of the control cows. As reported elsewhere, between lactation weeks 9 and 33 persistency (measured as the slope of decline in milk yield) was significantly improved by frequent milking (P<0.001), by calving in the Winter (P<0.001) and by additional concentrate (P<0.05). The cows were rebred after week 33. When analysis of persistency was extended up to week 20 of the recurring pregnancy only the frequency effect remained significant. Persistency was unaffected by the pregnancy up until pregnancy week 20 but was then greatly reduced (P<0.001). In this paper we report hormone concentrations. GH was unaffected by nutrition but was consistently elevated in the Winter calving group relative to the Spring. IGF1 and prolactin were both unaffected by nutrition and calving season, IGF1 tended to increase as lactation progressed but changes in prolactin were related to time of year more than stage of lactation. Insulin was not affected by nutrition and was lower in Winter calvers, but only during early lactation. Prior to rebreeding, lactation persistency was correlated (slightly) with [GH] but not with [IGF1] or [insulin] and was correlated significantly with changes in GH, IGF1 (both positive) and insulin (negative). In conclusion, whilst bovine lactation persistency is plastic and amenable to beneficial manipulation, the details of its endocrine control remain to be elucidated.     

Periparturient endocrine and metabolic changes in healthy cows and in cows affected by mastitis

Transition from pregnancy to lactation in dairy cows involves considerable metabolic adaptation. Additional stress is incurred during infections such as periparturient mastitis. Multiparous Holstein-Friesian cows kept under normal production conditions (n = 15) were used to evaluate changes in circulating metabolite and hormone concentrations from 5 days before to 5 days after calving. Insulin-like growth factor binding protein (IGFBP) profiles were also monitored. Marked time-related changes were observed for plasma thyroid hormone, IGF, cortisol, insulin, beta-hydroxybutyrate (BHB) and non-esterified fatty acid (NEFA) concentrations but not for plasma leptin. A decrease in IGF-II concentration and maximal intensity of the putative IGFBP-1 band occurred at parturition. When compared with the five healthy cows,low IGF-II levels were prolonged to day 2 post-partum in five cows with Escherichia coli-associated mastitis. However, marked decreases in IGFBP-2 band intensity were evident only in two of the four cases examined. Individual total ligand (IGF-I + IGF-II) concentration and IGFBP pattern prepartum were largely regained 5 days post-partum in all cows. Hormone and metabolite concentrations in the two cows with Staphylococcus aureus-associated mastitis were very similar to those in the five healthy cows. Plasma thyroxine (T4) was lower 2 days prepartum in the cows, which later developed Gram-negative mastitis. Multiregression analysis showed that variance in T4 concentration was significantly and independently associated with triiodothyronine (T3) and IGF-I positively and with cortisol negatively (R2 = 0.648). This study confirms the close inter-relationship between the thyroid hormone and IGF axes in cattle and indicates possible effects of Gram-negative mastitis infection on IGF-II metabolism.     

产前运动对围产期奶牛生理代谢指标的影响

本试验旨在研究产前运动对围产期奶牛生理代谢指标的影响，为围产期奶牛健康管理提供科学指导和理论依据。试验选取年龄相似，体况评分、胎次和预产期相近的经产荷斯坦奶牛24头，随机分为试验组（TRT组）和对照组（CON组），每组12头，统一饲养管理。于预产期前21 d开始，TRT组奶牛每日09：00和16：00以<3 km/h的速度运动1 h，每头奶牛每日总运动量为（4.0±0.2） km/d；CON组自由活动。分别在预产期前21、7 d、分娩当天及产后7、30 d （分别记为－21、－7、0、+7和+30 d），于晨饲前采集血液，测定血浆中非酯化脂肪酸（NEFA）、β-羟基丁酸（BHBA）、葡萄糖（GLU）、甘油三酯（TG）、胆固醇（CHOL）、肌酐（CREA）及尿素（UREA）浓度。结果显示，试验期间，TRT组血浆NEFA、BHBA浓度与CON组相比均呈下降趋势（0.05<P<0.1），－7 d时TRT组NEFA浓度显著低于CON组（P<0.05）；TRT组血浆GLU浓度变化较CON组平稳，在＋30 d极显著高于CON组（P<0.01）；两组血浆TG浓度均在分娩当天急剧下降，产前血浆TG浓度均极显著高于分娩后各时间点（P<0.01），＋30 d时TRT组极显著高于CON组（P<0.01）；血浆UREA、CREA浓度在两组间无显著差异（P>0.05）。综上，以<3 km/h的速度进行运动（4.0 km/d±0.2 km/d），可有效降低围产期奶牛血浆NEFA和BHBA浓度，缓解能量负平衡（NEB）压力。     

Plasma mineral and energy metabolite concentrations in dairy cows fed an anionic prepartum diet that did or did not have retained fetal membranes after parturition

OBJECTIVE: To compare plasma total calcium, phosphorus, magnesium, nonesterified fatty acids (NEFA), beta hydroxy butyrate (BHB), and glucose concentrations in parturient dairy cows that were fed an anionic prepartum diet between those with and without retained fetal membranes (RFM) at 24 hours after parturition. ANIMALS: 152 Holstein cows that calved during October through December of 1997 PROCEDURE: All cows were fed an anionic prepartum diet. Blood sample was taken within 6 hours after parturition from randomly selected cows. Thirty-nine cows had a diagnosis of RFM at 24 hours after parturition; 113 were not affected with RFM. At calving, body condition score (BCS; 1 [thin] to 5 [obese]), parity, and calving difficulty score were recorded. Plasma calcium, phosphorus, magnesium, NEFA, BHB, and glucose concentrations were compared between cows with or without RFM. RESULTS: Cows with RFM had significantly lower plasma calcium concentration soon after calving, compared with cows without RFM. Cows with a parity of > or = 3 had significantly lower plasma concentrations of calcium and higher concentrations of magnesium, compared with cows with a parity of 1 or 2. Cows with a BCS of > or = 3.25 at calving had significantly higher plasma concentrations of BHB than cows with a BCS of 2.75 to 3.0. Cows with dystocia had significantly higher plasma concentrations of glucose, compared with cows without dystocia. CONCLUSIONS AND CLINICAL RELEVANCE: In parturient cows fed a prepartum anionic diet, those with RFM have lower plasma calcium concentrations than cows without RFM, although this association does not prove a cause-effect relationship.     

Blood Metabolite Profiles in Cycling and Non‐cycling Friesian–Sanga Cross‐bred Cows Grazing Natural Pasture During the Post‐partum Period

An experiment was conducted to investigate the effect of plasma concentrations of the metabolic hormones [Growth hormone (GH), insulin and insulin‐like growth factor –I (IGF‐I)] and nutritional metabolites (Glucose, cholesterol, total protein, albumin, globulin, urea and creatinine) on the resumption of post‐partum ovarian activity in sixteen Friesian–Sanga cows grazing extensively on native grassland. Blood samples were taken from cows from week 1 to 16 post‐partum. Cows were classified as having resumed ovarian activity when a plasma progesterone concentration of ≥ 1.0 ng/ml was recorded for two consecutive weekly samples. Based on the resumption of ovarian activity, cows were classified as early‐cycling, late‐cycling or non‐cycling. The concentrations of the metabolic hormones were measured from week 1 to 10, while those of the nutritional metabolites were measured during week 1, 3, 5, 7 and 9 during the study period. The concentrations of the metabolic hormones, GH and insulin were similar (p > 0.05) in the three ovarian activity groups, likewise the concentrations of the nutritional metabolites, glucose, total protein, globulin, urea and creatinine. Plasma IGF‐I concentration was higher (p < 0.001) in early‐cycling (18.7 ± 0.74 ng/ml) than in late‐cycling (12.4 ± 0.75 ng/ml) and non‐cycling (10.4 ± 0.91 ng/ml) cows. Plasma cholesterol concentrations were significantly lower (p < 0.05) in early‐cycling (1.94 ± 0.15 mmol/l) compared with late‐cycling (2.48 ± 0.12 mmol/l) and non‐cycling (2.61 ± 0.11 mmol/l) cows. For plasma albumin concentrations, the levels recorded for early‐cycling cows were higher (40.7 ± 2.85 g/l) than in late‐cycling (34.4 ± 1.97 g/l) and non‐cycling (33.6 ± 2.66) cows. The results suggest that cows with lower plasma concentrations of IGF‐I and albumin, but higher plasma cholesterol concentrations were at risk of delayed resumption of post‐partum ovarian activity.     

Metabolic Responses of Periparturient Holstein Cows and Heifers Supplemented with Chromium Picolinate

Thirty-four Holstein cows, 18 primiparous and 16 multiparous, were used to determine the effects of supplemental Cr on carbohydrate and lipid metabolism during the transition period. From approximately 3 wk prior to anticipated calving date until parturition, Cr-treated cows were given 51 mg Cr picolinate via a gelatin capsule bolus three times weekly, equivalent to an average daily intake of approximately 2 ppm Cr. Control cows were given empty gelatin capsules. All cows were fed total mixed rations, with one ration fed to dry cows, a second to lactating cows for wk 1 of postpartum (transition), and a third to lactating cows thereafter. Blood samples were collected via jugular venipuncture at 1, 2, and 3 wk prior to anticipated calving date as well as immediately following calving, 3 d post calving, and 1, 2, and 3 wk post calving. Samples were analyzed for glucose, insulin, and nonesterified fatty acids (NEFA). Within 1 wk prior to calving, a frequently sampled intravenous glucose tolerance test was performed, and blood plasma samples were analyzed for concentrations of glucose and insulin. Plasma glucose response to the frequently sampled intravenous glucose tolerance test was evaluated by calculating the half-life and fractional turnover rate for the period from 2 to 19 min after glucose infusion. Supplemental Cr did not affect circulating concentrations of glucose, insulin, or NEFA (P>0.1). Plasma NEFA concentrations were greater in primiparous cows (P<0.01) throughout the experiment, with the difference being most apparent during the 3 wk postpartum. Glucose concentrations reached a greater peak at time of calving in primiparous cows than in multiparous cows (P=0.07). There was an increase in glucose clearance rate (P=0.06) and a trend toward decreased glucose half-life (P<0.1) in primiparous cows supplemented with Cr. Insulin peak concentrations were unaffected by treatment or parity (P>0.1). Data suggest that Cr supplementation may alter carbohydrate metabolism in primiparous cows during the transition period.     

Changes in circulating adiponectin and metabolic hormone concentrations during periparturient and lactation periods in Holstein dairy cows

Although our previous report demonstrated that adiponectin and AdipoR1 gene expressions changed among different lactation stages in the bovine mammary gland, its in vivo kinetics remain unclear in ruminant animals. In this study, we investigated the changes in circulating concentrations of adiponectin, as well as other metabolic hormones and metabolites, (i) during the periparturient period and (ii) among different lactation stages, in Holstein dairy cows. In experiment 1, serum adiponectin concentrations increased after parturition. Serum insulin concentrations were lower in the postpartum than prepartum period, whereas serum growth hormone (GH) concentrations increased in the postpartum period. Serum nonesterified fatty acids (NEFA) levels were increased during the postpartum period and were dependent on the parity. In experiment 2, there was no significant difference in plasma adiponectin concentrations among lactational stages. Plasma insulin concentrations tended to be lower in early lactation while plasma GH levels tended to be higher. Plasma NEFA concentrations were significantly lower in mid‐ and late‐lactation stages than non‐lactation stages. These findings indicate that elevation of serum adiponectin might be involved in energy metabolism just around parturition, and might exert its action through regulation of receptor expression levels in target tissues in each lactational stage in Holstein dairy cows.     

Measurement of ferritin and anti‐ferritin autoantibodies in serum and colostrum of Holstein and Japanese Black cows

Anti‐ferritin autoantibody is a ferritin‐binding protein commonly found in mammals; it is thought to form an immune complex with ferritin and thereby mediate the rapid clearance of circulating ferritin. The aim of this study is to determine concentrations of ferritin and anti‐ferritin autoantibodies (immunoglobulin (Ig)M, IgG and IgA) in serum and colostrum of Holstein (H) and Japanese Black (JB) cows within 24 h of normal calving. Blood and colostrum samples were collected from cows of various ages (2–11 years) and calving number (1–8 live births). Mean ferritin concentrations were higher in colostrum than in serum for both breeds, and higher colostrum ferritin concentrations were found in H than JB cows. IgA antibodies in serum and colostrum from both breeds had negligible ferritin‐binding activity. For both breeds, IgM and IgG antibodies had higher ferritin‐binding activity in colostrum than in serum. There was a significant correlation between IgM and IgG ferritin‐binding activities in serum and colostrum of H and JB cows. These results suggest that ferritin and IgM and IgG autoantibodies are actively transferred from the blood stream to the colostrum at prepartum or early lactation.     

Increasing selenium supply during the close-up dry period improves nutrient metabolism and attenuates inflammatory response after calving in dairy cows

The objective of this study was to investigate whether feeding selenium (Se)-replete cows a Se-yeast supplement in late pregnancy affects nutrient metabolism and inflammatory response during the periparturient period. Twenty cows were randomly assigned to two groups with 10 cows each. Cows in one group received Se-yeast at 0.3 mg Se/kg DM during the last 4 weeks before calving in addition to fed a TMR containing supplemented sodium selenite at 0.3 mg Se/kg DM (Se-yeast), while cows in another group were only fed a TMR containing supplemented sodium selenite at 0.3 mg Se/kg DM (Control). Blood samples were collected and analyzed for nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), glucose, insulin, tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, serum amyloid A (SAA), haptoglobin (Hp), and albumin. In control cows, plasma NEFA, IL-1β, IL-6, SAA, and Hp levels increased after calving, but glucose, insulin, and albumin levels decreased after parturition. Se-yeast supplemental cows had lower postpartum concentrations of NEFA, TNF-α, IL-1β, IL-6, SAA, and Hp, and higher postpartum levels of glucose, insulin, and albumin compared with control cows. The results indicate that feeding Se-replete cows a Se-yeast supplement in late pregnancy improves nutrient metabolism and attenuates the inflammatory response after calving.     

Metabolic and endocrine profiles and reproductive parameters in dairy cows under grazing conditions: effect of polymorphisms in somatotropic axis genes

Background

The present study hypothesized that GH-AluI and IGF-I-SnabI polymorphisms do change the metabolic/endocrine profiles in Holstein cows during the transition period, which in turn are associated with productive and reproductive parameters.

Methods

Holstein cows (Farm 1, primiparous cows, n = 110, and Farm 2, multiparous cows, n = 76) under grazing conditions were selected and GH and IGF-I genotypes were determined. Blood samples for metabolic/endocrine determinations were taken during the transition period and early lactation in both farms. Data was analyzed by farm using a repeated measures analyses including GH and IGF-I genotypes, days and interactions as fixed effects, sire and cow as random effects and calving date as covariate.

Results and Discussion

Frequencies of GH and IGF-I alleles were L:0.84, V:0.16 and A:0.60, B:0.40, respectively. The GH genotype was not associated with productive or reproductive variables, but interaction with days affected FCM yield in multiparous (farm 2) cows (LL yielded more than LV cows) in early lactation. The GH genotype affected NEFA and IGF-I concentrations in farm 1 (LV had higher NEFA and lower IGF-I than LL cows) suggesting a better energy status of LL cows.There was no effect of IGF-I genotype on productive variables, but a trend was found for FCM in farm 2 (AB cows yielded more than AA cows). IGF-I genotype affected calving first service interval in farm 1, and the interaction with days tended to affect FCM yield (AB cows had a shorter interval and yielded more FCM than BB cows). IGF-I genotype affected BHB, NEFA, and insulin concentrations in farm 1: primiparous BB cows had lower NEFA and BHB and higher insulin concentrations. In farm 2, there was no effect of IGF-I genotype, but there was an interaction with days on IGF-I concentration, suggesting a greater uncoupling somatropic axis in AB and BB than AA cows, being in accordance with greater FCM yield in AB cows.

Conclusion

The GH and IGF-I genotypes had no substantial effect on productive parameters, although IGF-I genotype affected calving-first service interval in primiparous cows. Besides, these genotypes may modify the endocrine/metabolic profiles of the transition dairy cow under grazing conditions.     

Energy balance,leptin, NEFA and IGF-I plasma concentrations and resumption of post partum ovarian activity in swedish red and white breed cows

In the purpose to provide further information in respect of the relationship between metabolism and post partum (PP) ovarian activity resumption in dairy cows, the aim of the present study was to characterize the energy balance (EB) and leptin, NEFA and IGF-I plasma levels in Swedish Red and White (SRW) cows with and without ovarian activity re-initiation within 7 weeks PP. The study was conducted on 12 primiparous SRW cows fed the same diet as total mixed ration for ad libitum intake. The EB was calculated weekly from parturition until seven weeks PP. Blood samples were collected weekly from one week before until 7 weeks after calving for leptin, NEFA and IGF-I analysis. For progesterone (P4) analysis, blood samples were collected two times per week from parturition until the end of the study. P4 profile was used in addition to the clinical examination to detect cows with and without ovarian activity resumption. The clinical and ultrasonographic examination, coupled with P4 profile analysis showed the resumption of ovarian activity within 7 weeks after calving in 8 (group A) and no ovarian resumption in 4 cows (group B). No significant differences were detected in the whole period of observation in the amount of milk production between the two groups, while the mean milk protein content was significantly lower in group B at the third week PP. The calculated EB was negative in both groups in the first three weeks after calving, but more marked in group B. NEFA and Leptin plasma levels did not show significant differences between the two groups. In conclusion, the results of the present study showed that, when low milk producing primiparous cows are concerned, no significant differences in BW loss, milk yield, EB and leptin and NEFA plasma levels between the cows with and without resumption of ovarian activity within 7 weeks post partum were seen. However, significantly higher IGF-I levels in the first two weeks after calving were found in cows with post partum ovarian activity resumption, highlighting the important role of IGF-I as sensitive signal between metabolism and reproduction.     

Nutritional anestrus in beef cows: concentrations of glucose and nonesterified fatty acids in plasma and insulin in serum

Twenty-two nonlactating Hereford cows exhibiting normal estrous cycles were fed either maintenance (M) or restricted (R) diets until most of the R cows became anestrus; R cows then were fed 160% of the M diet until estrous cycles resumed. Concentrations of progesterone, glucose, insulin and nonesterified fatty acids (NEFA) were determined in weekly blood samples. Blood also was collected frequently, before and after i.v. infusion of 300 ml of a 40% glucose solution, to evaluate responses in blood concentrations of glucose and insulin when cows were exhibiting normal estrous cycles, when R cows were initiating anestrus, during anestrus, and at the reinitiation of estrous cycles. Losses in BW and body condition score in R cows were associated with reduced (P less than .01) concentrations of glucose and insulin and greater (P less than .01) concentrations of NEFA in blood plasma compared with those of M cows. During normal estrous cycles, disappearance of infused glucose from plasma and concentrations of insulin in serum were similar for R and M cows. Glucose disappearance from plasma was retarded and serum concentrations of insulin remained increased for a longer time after glucose infusion in R at the start of anestrus compared with M cows (P less than .01). Similarly, during anestrus, the rate of glucose disappearance was slower for R cows (P less than .01). During refeeding of R cows, disappearance of infused glucose was similar for R and M cows. In conclusion, reduced concentrations of glucose and insulin and increased concentrations of NEFA in blood were associated with nutritional anestrus and the glucoregulatory effects of insulin were compromised during nutritional anestrus.     

Effect of short-term fasting on plasma concentrations of leptin and other hormones and metabolites in dairy cattle

We determined the effects of short-term fasting and refeeding on temporal changes in plasma concentrations of leptin, insulin, insulin-like growth factor- 1 (IGF-1), growth hormone (GH), glucose, and nonesterified fatty acids (NEFA), in early lactating cows, non-lactating pregnant cows, and postpubertal heifers. In experiment 1, Holstein cows in early lactation were either fed ad libitum (Control, n=5) or feed deprived for 48 h (Fasted, n=6). Plasma leptin, insulin, and glucose concentrations rapidly declined (P<0.05) within 6h, and IGF-1 by 12h, but all these variables sharply returned to control levels (P>0.10) within 2h of refeeding. Plasma NEFA and GH concentrations were elevated (P<0.05) by 4 and 36 h of fasting and returned to control levels (P>0.10) by 8 and 24h after refeeding, respectively. In experiment 2, four ruminally cannulated pregnant non-lactating Holstein cows were used in a cross-over design and were fasted for 48 h (Fasted) or fasted with partial evacuation of rumen contents (Fasted-Evac). The plasma variables measured did not differ (P>0.10) between Fasted and Fasted-Evac cows. Plasma leptin, insulin, and IGF-1 concentrations were reduced by 10, 6, and 24h of fasting, respectively, in Fasted-Evac cows; and these variables were reduced by 24h in Fasted cows (P<0.05). Plasma glucose levels were reduced (P<0.05) by 48 h of fasting in both groups of fasted animals. Plasma NEFA and GH levels were increased (P<0.05) by 12 and 48 h of fasting, respectively. In experiment 3, postpubertal Holstein heifers were either fed ad libitum (Control, n=4) or feed deprived for 72 h (Fasted, n=5). Concentrations of leptin, insulin, IGF-1, and glucose in plasma were reduced (P<0.05) by 24, 10, 24, and 48 h of fasting, respectively. Plasma NEFA concentrations increased (P<0.05) by 4h, of fasting while GH levels were not significantly (P>0.10) affected by fasting. Collectively, our data provide evidence that plasma leptin concentrations are reduced with short-term fasting and rebound on refeeding in dairy cattle with the response dependent on the physiological state of the animals. Compared to the rapid induction of hypoleptinemia with fasting of early lactation cows, the fasting-induced hypoleptinemia was delayed in non-lactating cows and postpubertal heifers.     

Plasma parameters related to energy and lipid metabolism in periparturient Modenese and Italian Friesian cows

The aim of this work was to compare energy and lipid metabolism during the peripartum period between Modenese (MO) and Italian Friesian (IF) cows. The study was carried out on 33 pluriparous pregnant cows, 19 IF and 14 MO, reared together in the same herd and kept under equal conditions of management and nutrition. Blood was sampled from jugular vein starting 4 week before expected calving date until 4 week post‐calving, once weekly. Plasma was analysed for glucose, NEFA, BHBA, triglycerides and cholesterol concentrations. Body condition score (BCS) was assessed weekly after blood sampling. Data from antepartum (a.p.) and post‐partum (p.p.) periods were separately analysed as repeated measures by a linear mixed models with the effect of breed, time and their interaction as main factors and random cow within breed. The energy status differed between the two breeds during the peripartum period. We observed higher BCS a.p. and p.p. and lower BCS variations p.p. in MO compared to IF group. Modenese cows showed lower glucose and cholesterol concentrations (p < 0.001), but higher NEFA values, NEFA to cholesterol and NEFA to albumin ratios (p < 0.001) during a.p.; on the contrary, IF cows had higher (p < 0.05) cholesterol, NEFA, BHBA levels and NEFA to albumin ratio than MO ones during p.p. The differences observed between the two breeds suggest how MO cows are subjected to lipid mobilization during late gestation; on the contrary, IF cows are predisposed to mobilize their lipid reserves at the beginning of lactation to support high production. The results indicate a diverse ability to cope with metabolic stress and suggest the hypothesis that the differences in concentrations of plasma parameters and their variation amplitude around the calving period might depend on the different genetic merit for milk production between the two breeds.     

Nutritional plane and selenium supply during gestation affect yield and nutrient composition of colostrum and milk in primiparous ewes

The objectives were to investigate effects of nutritional plane and Se supply during gestation on yield and nutrient composition of colostrum and milk in first parity ewes. Rambouillet ewe lambs (n = 84, age = 240 ± 17 d, BW = 52.1 ± 6.2 kg) were allocated to 6 treatments in a 2 × 3 factorial array. Factors included Se [adequate Se (ASe, 11.5 μg/kg of BW) or high Se (HSe, 77.0 μg/kg of BW)] initiated at breeding, and nutritional plane [60 (RES), 100 (CON), or 140% (HIH) of requirements] initiated at d 40 of gestation. Ewes were fed individually from d 40, and lambs were removed at parturition. Colostrum was milked from all ewes at 3 h postpartum, and one-half of the ewes (n = 42) were transitioned to a common diet meeting lactation requirements and mechanically milked for 20 d. Colostrum yield was greater (P = 0.02) for HSe ewes than ASe, whereas CON had greater (P < 0.05) colostrum yield than RES and HIH. Colostrum Se (%) was greater (P < 0.01) for HSe than ASe. Colostrum from ewes fed HSe had less (P = 0.03) butterfat (%), but greater (P ≤ 0.05) total butterfat, solids-not-fat, lactose, protein, milk urea N, and Se than ASe. Colostrum from HIH ewes had greater (P ≤ 0.02) solids-not-fat (%) than RES, whereas RES had greater (P ≤ 0.04) butterfat (%) than CON and HIH. Colostrum from ewes fed the CON diet had greater (P = 0.01) total butterfat than HIH. Total solids-not-fat, lactose, and protein were greater (P < 0.05) in colostrum from CON than RES and HIH. Ewes fed HSe had greater (P < 0.01) milk yield (g/d and mL/d) than ASe, and CON and HIH had greater (P < 0.01) yield than RES. Milk protein (%) was greater (P ≤ 0.01) in RES compared with CON or HIH. Ewes fed HSe had greater (P < 0.01) milk Se (μg/g and mg/d) than ASe on each sampling day. Milk from CON and HIH ewes had greater (P < 0.01) total solids-not-fat, lactose, protein, and milk urea N than RES. Total Se was greater (P = 0.02) in milk from ewes fed the CON diet compared with RES. Somatic cell count and total somatic cells were greater (P ≤ 0.05) in milk from CON than RES. A cubic effect of day (P ≥ 0.01) was observed for milk yield (g and mL). Butterfat, solids-not-fat, lactose, milk urea N, and Se concentration responded quadratically (P ≤ 0.01) to day. Protein (%), total butterfat, and total Se, and somatic cells (cells/mL and cells/d) decreased linearly (P < 0.01) with day. Results indicate that gestational nutrition affects colostrum and milk yield and nutrient content, even when lactational nutrient requirements are met.