Longitudinal characterization of the metabolome of dairy cows transitioning from one lactation to the next: Investigations in the liver.

This study aimed to investigate the metabolic changes in the livers of dairy cows from 1 wk before dry off to 1 wk after calving. Twelve high-yielding Holstein cows were included in a longitudinal study and housed in a tiestall barn. The cows were dried off at 6 wk before the expected calving date (dry period length = 42 d). During the entire lactation, the cows were milked twice daily at 0600 and 1700 h. Liver biopsies were taken from each cow at 4 different times: wk -7 (before drying off), -5 (after drying off), -1 and +1 relative to calving. A targeted metabolomics approach was performed by liquid chromatography and flow injection with electrospray ionization triple quadrupole mass spectrometry using the MxP Quant 500 kit (Biocrates Life Sciences AG). A total of 185 metabolites in the liver were used for the final data analysis. Principal component analysis revealed a clear separation by days of sampling, indicating a notable shift in metabolic phenotype from late lactation to the dry period and further changes after calving. Changes were observed in several classes of compounds, including AA and biogenic amines. In particular, the changes in acylcarnitines (AcylCN), phosphatidylcholines (PC), sphingomyelins (SM), and bile acids (BA) indicated extensive remodeling of the hepatic lipidome. The changes in AcylCN concentrations in early lactation suggest incomplete fatty acid oxidation in the liver, possibly indicating mitochondrial dysfunction or enzymatic imbalance. In addition, the changes in PC and SM species in early lactation indicate altered cell membrane composition, which may affect cell signaling and functionality. In addition, changes in BA concentrations and profiles indicate dynamic adaptations in BA synthesis, as well as lipid digestion and absorption during the observation period. In particular, principal component analysis showed an overlapping distribution of liver metabolites in primiparous and multiparous cows, indicating no significant difference between these groups. In addition, Volcano plots showed similar liver metabolism between primiparous and multiparous cows, with no significant fold changes (>1.5) in any metabolite at significant P-values (false discovery rate <0.05). These results provide valuable insight into the physiological ranges of liver metabolites during dry period and calving in healthy dairy cows and should contribute to the design and interpretation of future metabolite-based studies of the transition dairy cow.

Evaluating lactation performance of multiparous dairy cattle to prepartum and/or postpartum supplementation of fat-embedded calcium gluconate.

Prebiotic compounds may be supplemented in the diet to improve animal health and performance in a variety of ways. In dairy cattle, the transition from pregnancy through parturition and lactation represents a critical life stage with many concurrent stressors. The objectives of this study were to evaluate responses to the provision of a hindgut-targeted prebiotic compound (calcium gluconate; HFCG) when supplemented prepartum and/or postpartum in a 2 × 2 factorial design. One hundred and sixty-four multiparous Holstein cattle were enrolled and followed from approximately 21 d prior to calving until 100 d of lactation. Treatments were administered as a pelleted compound feed offered in the rotary milking parlor once daily prepartum and thrice daily postpartum. Information pertaining to milk production and body weight were automatically recorded by the milking equipment, and information pertaining to reproductive and health performance was recorded by farm staff. Cattle that received HFCG prepartum were confirmed pregnant approximately 21 d earlier (P = 0.024). Cattle that received HFCG both pre- and postpartum had 9% to 10% higher yields of milk protein, fat, and energy-corrected milk (P ≤ 0.037) from weeks 4 to 9 of lactation relative to those that received HFCG exclusively prepartum. Conversely, cattle that received HFCG exclusively postpartum had 9% to 10% higher yields of milk protein, fat, and energy-corrected milk (P ≤ 0.037) from weeks 9 to 14 of lactation relative to those that received exclusively the negative control in both periods. The mechanism underlying these responses remains unclear, however, we hypothesize that these responses are due to localized reductions in inflammation in the gut and/or signaling to extragastrointestinal tissues altering energy partitioning and balance.

Effects of supplemental calcium gluconate embedded in a hydrogenated fat matrix on lactation, digestive, and metabolic variables in dairy cattle.

There is growing evidence suggesting that by improving gut integrity and function, less energy is partitioned toward immune responses related to xenobiotic infiltration, sparing energy for productive purposes. Gluconic acid and its salts have previously shown prebiotic effects in the lower gut of nonruminant animals, where they serve as a precursor for butyrate, although evidence in ruminants is limited. Butyrate and its fermentative precursors have demonstrated multiple beneficial effects to gastrointestinal ecology, morphology, and function, such as the stimulation of epithelial cell proliferation and improvement of gut barrier function and ecology. The objective of this study was to evaluate changes in milk production, milk fatty acid composition, and fecal and blood parameters in lactating dairy cattle fed a hydrogenated fat-embedded calcium gluconate (HFCG) supplement designed to target the hindgut for calcium gluconate delivery. In addition, the effects of a compound feed processing method (i.e., incorporated into a mash or an extruded pellet) were tested to evaluate the effect of extrusion on product efficacy. Forty-five lactating Holstein cows at approximately 165 d in milk were used in a 3 × 3 Latin square consisting of three 28-d periods, during which animals were offered a basal ration mixed with 3 different compound feeds: a negative control in mash form containing no HFCG, or the HFCG supplement fed at a target rate of 16 g/d, delivered in either a mash or pelleted form. Supplementation of HFCG tended to increase yields of milk fat and fat- and energy-corrected milk. Total yields and concentrations of milk fatty acids ≥18 carbons in length tended to increase in response to HFCG. Plasma nonesterified fatty acids and milk urea increased in HFCG treatments. No differences were observed in fecal pH or fecal concentrations of volatile fatty acids, with the exception of isobutyrate, which decreased in HFCG-fed cows. Changes in milk fatty acid profile suggest that increased milk fat yield was driven by increased incorporation of preformed fatty acids, supported by increased circulating nonesterified fatty acid. Future research investigating the mode of action of HFCG at the level of the hindgut epithelium is warranted, as measured fecal parameters showed no response to treatment.

The effects of zinc amino acid complex on biomarkers of gut integrity, inflammation, and metabolism in heat-stressed ruminants.

Study objectives were to evaluate the effects of replacing 40 mg/kg of dietary Zn from Zn sulfate (ZS) with Zn amino acid complex (ZA; Zinpro Corporation, Eden Prairie, MN) on inflammation and intestinal integrity in heat-stressed and pair-fed (PF) ruminants. Forty Holstein steers (173.6 ± 4.9 kg) were randomly assigned to 1 of 5 dietary-environmental treatments: (1) thermoneutral (TN) ad libitum with 75 mg/kg of dry matter (DM) ZS (ZSCON); (2) TN pair-fed with 75 mg/kg DM ZS (ZSPF); (3) TN pair-fed with 40 mg/kg DM ZA and 35 mg/kg DM ZS (ZAPF); (4) heat stress (HS) ad libitum with 75 mg/kg DM ZS (ZSHS); and (5) HS ad libitum 40 mg/kg DM ZA and 35 mg/kg DM ZS (ZAHS). Before study initiation, calves were fed their respective diets for 21 d. Following the pre-feeding phase, steers were transferred into environmental chambers and were subjected to 2 successive experimental periods. During period 1 (5 d), all steers were fed their respective diets ad libitum and housed in TN conditions (20.2 ± 1.4°C, 30.4 ± 4.3% relative humidity). During period 2 (6 d), ZSHS and ZAHS steers were exposed to cyclical HS conditions (27.1 ± 1.5°C to 35.0 ± 2.9°C, 19.3 ± 3.5% relative humidity), whereas the ZSCON, ZSPF, and ZAPF steers remained in TN conditions and were fed ad libitum or pair-fed relative to their ZSHS and ZAHS counterparts. Overall, steers exposed to HS had markedly increased rectal temperature (0.83°C), respiration rate (26 breaths per min), and skin temperature (8.00°C) relative to TN treatments. Rectal temperature from ZAHS steers was decreased (0.24°C) on d 4 to 6 of HS relative to ZSHS steers. Regardless of diet, HS decreased DMI (18%) relative to ZSCON steers. Circulating glucose from HS and PF steers decreased (16%) relative to ZSCON steers. Heat stress and nutrient restriction increased circulating nonesterified fatty acids 2- and 3-fold, respectively, compared with ZSCON steers. Serum amyloid A increased ~2-fold in PF relative to ZSCON and HS steers. We detected no treatment effect on blood pH; however, ZAHS steers had increased HCO3 relative to ZSHS. Relative to ZSHS, ZAHS steers had increased jejunum villi height (25%), a tendency for increased ileum villi height (9%), and decreased duodenal villi width (16%). In summary, ZA supplementation has some beneficial effects on thermal indices, intestinal architecture characteristics, and biomarkers of leaky gut in heat-stressed steers, indicative of an ameliorated heat load, and thus may be a nutritional strategy to minimize negative consequences of HS.

Effects of source on bioavailability of selenium, antioxidant status, and performance in lactating dairy cows during oxidative stress-inducing conditions.

In the current study, we used heat stress (HS) as an oxidative stress model to examine the effects of hydroxy-selenomethionine (HMSeBA), an organic selenium source, on selenium's bioavailability, antioxidant status, and performance when fed to dairy cows. Eight mid-lactation Holstein dairy cows (141 ± 27 d in milk, 35.3 ± 2.8 kg of milk/d, parity 2 or 3) were individually housed in environmental chambers and randomly assigned to 1 of 2 treatments: inorganic Se supplementation (sodium selenite; SS; 0.3 mg of Se/kg of dry matter; n = 4) or HMSeBA supplementation (0.3 mg of Se/kg of dry matter; n = 4). The trial was divided into 3 continuous periods: a covariate period (9 d), a thermal neutral (TN) period (28 d), and a HS period (9 d). During the covariate and TN periods, all cows were housed in TN conditions (20°C, 55% humidity). During HS, all cows were exposed to cyclical HS conditions (32-36°C, 40% humidity). All cows were fed SS during the covariate period, and dietary treatments were implemented during the TN and HS periods. During HS, cows fed HMSeBA had increased Se concentrations in serum and milk, and total Se milk-to-serum concentration ratio compared with SS controls. Superoxide dismutase activity did not differ between Se sources, but we noted a treatment by day interaction in glutathione peroxidase activity as HS progressively reduced it in SS controls, whereas it was maintained in HMSeBA cows. Supplementation with HMSeBA increased total antioxidant capacity and decreased malondialdehyde, hydrogen peroxide, and nitric oxide serum concentrations compared with SS-fed controls. We found no treatment effects on rectal temperature, respiratory rate, or dry matter intake. Supplementing HMSeBA tended to increase milk yield and decrease milk fat percentage. No other milk composition parameters differed between treatments. We observed no treatment effects detected on blood biochemistry, except for a lower alanine aminotransferase activity in HMSeBA-fed cows. These results demonstrate that HMSeBA supplementation decreases some parameters of HS-induced oxidative stress.

Effects of heat stress and insulin sensitizers on pig adipose tissue.

Heat stress (HS) negatively impacts several swine production variables, including carcass fat quality and quantity. Pigs reared in HS have more adipose tissue than energetically predicted, explainable, in part, by HS-induced hyperinsulinemia. Study objectives were to evaluate insulin's role in altering fat characteristics during HS via feeding insulin-sensitizing compounds. Forty crossbred barrows (113 ± 9 kg BW) were randomly assigned to one of five environment by diet treatments: 1) thermoneutral (TN) fed ad libitum (TNAL), 2) TN and pair-fed (TNPF), 3) HS fed ad libitum (HSAL), 4) HS fed ad libitum with sterculic oil (SO) supplementation (HSSO; 13 g/d), and 5) HS fed ad libitum with dietary chromium (Cr) supplementation (HSCr; 0.5 mg/d; Kemin Industries, Des Moines, IA). The study consisted of three experimental periods (P). During P0 (2 d), all pigs were exposed to TN conditions (23 ± 3 °C, 68 ± 10% RH) and fed ad libitum. During P1 (7 d), all pigs received their respective dietary supplements, were maintained in TN conditions, and fed ad libitum. During P2 (21 d), HSAL, HSSO, and HSCr pigs were fed ad libitum and exposed to cyclical HS conditions (28 to 33 °C, 58 ± 10% RH). The TNAL and TNPF pigs remained in TN conditions and were fed ad libitum or pair-fed to their HSAL counterparts. Rectal temperature (TR), respiration rate (RR), and skin temperature (TS) were obtained daily at 0600 and 1800 h. At 1800 h, HS exposed pigs had increased TR, RR, and TS relative to TNAL controls (1.13 °C, 48 bpm, and 3.51 °C, respectively; P < 0.01). During wk 2 and 3 of P2, HSSO pigs had increased 1800 h TR relative to HSAL and HSCr (~0.40 and ~0.42 °C, respectively; P ≤ 0.05). Heat stress decreased ADFI and ADG compared to TNAL pigs (2.24 vs. 3.28 and 0.63 vs. 1.09 kg/d, respectively; P < 0.01) and neither variable was affected by SO or Cr supplementation. Heat stress increased or tended to increase moisture content of abdominal (7.7 vs. 5.9%; P = 0.07) and inner s.c. (11.4 vs. 9.8%; P < 0.05) adipose depots compared to TNAL controls. Interestingly, TNPF pigs also had increased adipose tissue moisture content and this was most pronounced in the outer s.c. depot (15.0 vs. 12.2%; P < 0.01) compared to TNAL pigs. Heat stress had little or no effect on fatty acid composition of abdominal, inner, and outer s.c. adipose tissue depots. In summary, the negative effects of HS on fat quality do not appear to be fatty acid composition related, but may be explained by increased adipose tissue moisture content.

Efficiency and demographics of a high-yield dairy ewe farm with two managing systems involving five or 10 lambings per year.

This study assessed milk productivity, demographic characteristics and workload distribution on a single high-yield dairy ewe farm in Spain (Avila, Spain; continental climate, latitude of 40.90 N, altitude of 900 m) over a 7-year period considering a transition from a herd management system involving five lambings per year (5LY) to a system involving 10 lambings per year (10LY). The 5LY system was practiced on the farm from 2010 to 2012 and the 10LY system from 2014 to 2015, with 2009 and 2013 being considered transition years. During this period, 27 415 lactations were recorded from an average of 3746 Lacaune sheep/year. Several productivity parameters were higher in 2014 to 2015 than in 2010 to 2012: milk yield/lactation (370±156 v. 349±185 l), lactation length (218±75 v. 192±75 days) and dry period length (53.5±38.3 v. 69.1±34.8 days) (all P<0.0001). During 2014 to 2015, investment in new lambing facilities was possible, workload was distributed more uniformly throughout the year, workload per worker was smaller, rate of ewe culling was lower (35.39±0.53% v. 42.51±7.51%), ewe longevity was greater and higher-order lactations were more numerous (P<0.0001). On the other hand, during 2010 to 2012, daily production was higher (1.73±1.66 v. 1.70±0.62 l/day; P=0.038), the interlambing period was shorter (283±50 v. 302±44 days; P<0.0001) and lambings/ewe per year were greater (1.42±0.01 v. 1.30±0.01; P<0.05). These results suggest that a 10LY herd management system can be compatible with profitability, productivity and good animal and worker's welfare on a high-yield dairy farm, and may even be associated with better outcomes than a 5LY system.

Characterizing effects of feed restriction and glucagon-like peptide 2 administration on biomarkers of inflammation and intestinal morphology.

Inadequate feed consumption reduces intestinal barrier function in both ruminants and monogastrics. Objectives were to characterize how progressive feed restriction (FR) affects inflammation, metabolism, and intestinal morphology, and to investigate if glucagon-like peptide 2 (GLP2) administration influences the aforementioned responses. Twenty-eight Holstein cows (157 ± 9 d in milk) were enrolled in 2 experimental periods. Period 1 [5 d of ad libitum (AL) feed intake] served as baseline for period 2 (5 d), during which cows received 1 of 6 treatments: (1) 100% of AL feed intake (AL100; n = 3), (2) 80% of AL feed intake (n = 5), (3) 60% of AL feed intake (n = 5), (4) 40% of AL feed intake (AL40; n = 5), (5) 40% of AL feed intake + GLP2 administration (AL40G; 75 µg/kg of BW s.c. 2×/d; n = 5), or (6) 20% of AL feed intake (n = 5). As the magnitude of FR increased, body weight and milk yield decreased linearly. Blood urea nitrogen and insulin decreased, whereas nonesterified fatty acids and liver triglyceride content increased linearly with progressive FR. Circulating endotoxin, lipopolysaccharide binding protein, haptoglobin, serum amyloid A, and lymphocytes increased or tended to increase linearly with advancing FR. Circulating haptoglobin decreased (76%) and serum amyloid A tended to decrease (57%) in AL40G relative to AL40 cows. Cows in AL100, AL40, and AL40G treatments were euthanized to evaluate intestinal histology. Jejunum villus width, crypt depth, and goblet cell area, as well as ileum villus height, crypt depth, and goblet cell area, were reduced (36, 14, 52, 22, 28, and 25%, respectively) in AL40 cows compared with AL100 controls. Ileum cellular proliferation tended to be decreased (14%) in AL40 versus AL100 cows. Relative to AL40, AL40G cows had improved jejunum and ileum morphology, including increased villus height (46 and 51%), villus height to crypt depth ratio (38 and 35%), mucosal surface area (30 and 27%), cellular proliferation (43 and 36%), and goblet cell area (59 and 41%). Colon goblet cell area was also increased (48%) in AL40G relative to AL40 cows. In summary, progressive FR increased circulating markers of inflammation, which we speculate is due to increased intestinal permeability as demonstrated by changes in intestinal architecture. Furthermore, GLP2 improved intestinal morphology and ameliorated circulating markers of inflammation. Consequently, FR is a viable model to study consequences of intestinal barrier dysfunction and administering GLP2 appears to be an effective mitigation strategy to improve gut health.

Estimating glucose requirements of an activated immune system in growing pigs.

Activated immune cells become obligate glucose utilizers, and a large i.v. lipopolysaccharide (LPS) dose causes insulin resistance and severe hypoglycemia. Therefore, study objectives were to quantify the amount of glucose needed to maintain euglycemia following an endotoxin challenge as a proxy of leukocyte glucose requirements. Fifteen fasted crossbred gilts (30.3 ± 1.7 kg) were bilaterally jugular catheterized and assigned 1 of 2 i.v. bolus treatments: control (CON; 10 mL sterile saline; = 7) or LPS challenge + euglycemic clamp (LPS-Eu; 055:B5; 5 µg/kg BW; 50% dextrose infusion to maintain euglycemia; = 8). Following administration, blood glucose was determined every 10 min and dextrose infusion rates were adjusted in LPS-Eu pigs to maintain euglycemia for 8 h. Pigs were fasted for 8 h prior to the bolus and remained fasted throughout the challenge. Rectal temperature was increased in LPS-Eu pigs relative to CON pigs (39.8 vs. 38.8°C; < 0.01). Relative to the baseline, CON pigs had 20% decreased blood glucose from 300 to 480 min postbolus ( = 0.01) whereas circulating glucose content in LPS-Eu pigs did not differ ( = 0.96) from prebolus levels. A total of 116 ± 8 g of infused glucose was required to maintain euglycemia in LPS-Eu pigs. Relative to CON pigs, overall plasma insulin, blood urea nitrogen, ß-hydroxybutrate, lactate, and LPS-binding protein were increased in LPS-Eu pigs (295, 108, 29, 133, and 13%, respectively; ≤ 0.04) whereas NEFA was decreased (66%; < 0.01). Neutrophils in LPS-Eu pigs were decreased 84% at 120 min postbolus and returned to CON levels by 480 min ( < 0.01). Overall, lymphocytes, monocytes, eosinophils, and basophils were decreased in LPS-Eu pigs relative to CON pigs (75, 87, 70, and 50%, respectively; ≤ 0.05). These alterations in metabolism and the large amount of glucose needed to maintain euglycemia indicate nutrient repartitioning away from growth toward the immune system. Glucose is an important fuel for the immune system, and data from this study established that the glucose requirements of an intensely and acutely activated immune system in growing pigs are approximately 1.1 g/kg BW/h.

Technical note: A procedure to estimate glucose requirements of an activated immune system in steers.

Infection and inflammation impede efficient animal productivity. The activated immune system ostensibly requires large amounts of energy and nutrients otherwise destined for synthesis of agriculturally relevant products. Accurately determining the immune system's in vivo energy needs is difficult, but a better understanding may facilitate developing nutritional strategies to maximize productivity. The study objective was to estimate immune system glucose requirements following an i.v. lipopolysaccharide (LPS) challenge. Holstein steers (148 ± 9 kg; = 15) were jugular catheterized bilaterally and assigned to 1 of 3 i.v. TREATMENTS: control (CON; 3 mL saline; = 5), LPS-administered controls (LPS-C; 055:B5; 1.5 mg/kg BW; = 5), and LPS + euglycemic clamp (LPS-Eu; 1.5 mg/kg BW; 50% dextrose infusion to maintain euglycemia; = 5). In LPS-Eu steers, postbolus blood samples were analyzed for glucose every 10 min. Dextrose infusion rates were adjusted to maintain euglycemia for 720 min. All steers were fasted during the challenge. Samples for later analysis were obtained at 180, 360, 540, and 720 min relative to LPS administration. Rectal temperature was increased ∼0.5°C in both LPS treatments relative to CON steers ( = 0.01). Steers in both LPS treatments were hyperglycemic for ∼3 h postbolus; thereafter, blood glucose was markedly decreased (30%; < 0.01) in LPS-C relative to both CON and LPS-Eu steers. A total of 516 ± 65 g of infused glucose was required to maintain continuous euglycemia in LPS-Eu steers. Circulating insulin increased in LPS-C and LPS-Eu steers relative to CON (∼70% and ∼20 fold, respectively; < 0.01). Circulating NEFA increased similarly with time for both CON and LPS-C compared to LPS-Eu steers (∼43%; < 0.01). Plasma L-lactate and LPS binding protein increased (∼198 and ∼90%, respectively; < 0.01) and ionized calcium decreased (18%; < 0.01) in both LPS treatments relative to CON steers. Circulating white blood cells decreased initially in LPS-Eu and LPS-C relative to controls (180 min; 85%) followed by a progressive increase with time ( = 0.02). Blood neutrophils followed the same pattern; however, at 720 min, neutrophils were decreased in LPS-Eu compared to LPS-C, resulting in a decreased neutrophil-to-lymphocyte ratio (54%; = 0.03). The large amount of glucose needed to maintain euglycemia indicates extensive repartitioning of nutrients away from growth and the importance of glucose as a fuel for the immune system.