Concentrates For Dairy Cows Research Articles

Liver copper concentration dynamics with different methods of injectable copper supplementation in dairy cows in New Zealand

ABSTRACT Aims To compare the responses of liver Cu concentrations in dairy cows between three forms of injectable Cu supplementation and a negative control group. Methods Across two dairy farms in North Canterbury, New Zealand, 80 mid-lactation dairy cows (n = 28 and 52 per farm) were randomly allocated to four treatment groups: (a) 100-mg or (b) 200-mg dose of Cu administered as Ca Cu EDTA; (c) 75-mg dose of Cu as disodium Cu EDTA combined with Se, Zn, and Mn; or (d) no treatment (negative control). Each treatment group contained 20 cows. Groups were balanced for age, plasma Cu and pre-treatment liver Cu concentration. Blood samples and liver biopsies were collected prior to treatment. Six liver biopsies were performed on the same cow over a period of 70 days and the concentration of liver Cu was measured over time and compared to pre-treatment baseline. A mixed, multivariable, linear regression model was constructed to determine the effect of treatment on the change in liver Cu concentration compared to pre-treatment concentrations, accounting for repeated measurements taken from each cow. Results There was a difference in the distribution of pre-treatment liver Cu concentration between farms (p = 0.008), with medians of 1,400 (IQR 1,200–1,625) and 1,050 (IQR 805–1,425) µmol/kg on Farms 1 and 2, respectively. There was an interaction between treatment group, study day, and farm, with a treatment effect confirmed only on Farm 2. In the final model, the predicted change in liver Cu concentration (compared to pre-treatment concentrations) among cows on Farm 2 that were treated with 200 mg of Ca Cu EDTA was significantly higher than that of control cows on Days 3, 14, 28 and 42, peaking on Day 14 with a difference of 325.35 (95% CI = 97.00–554.03) µmol/kg. The study found no associations between changes in liver Cu concentration and age or prior plasma Cu concentration. The intraclass correlation coefficient was 0.57 (95% CI = 0.45–0.66), indicating the proportion of variability in changes in liver Cu concentration attributable to inter-cow variation. Conclusions and clinical relevance This study shows there are differences in response to injectable Cu supplementation at the farm level and wide variation in liver Cu among cows from the same farm. On one farm, a 200-mg dosage of Ca Cu EDTA significantly increased liver Cu concentration for at least 42 days.

Maternal supplementation with n-3 fatty acids affects placental lipid metabolism, inflammation, oxidative stress, the endocannabinoid system, and the neonate cytokine concentrations in dairy cows

BackgroundThe placenta plays a crucial role in supporting and influencing fetal development. We compared the effects of prepartum supplementation with omega-3 (n-3) fatty acid (FA) sources, flaxseed oil (FLX) and fish oil (FO), on the expression of genes and proteins related to lipid metabolism, inflammation, oxidative stress, and the endocannabinoid system (ECS) in the expelled placenta, as well as on FA profile and inflammatory response of neonates. Late-pregnant Holstein dairy cows were supplemented with saturated fat (CTL), FLX, or FO. Placental cotyledons (n = 5) were collected immediately after expulsion, and extracted RNA and proteins were analyzed by RT-PCR and proteomic analysis. Neonatal blood was assessed for FA composition and concentrations of inflammatory markers.ResultsFO increased the gene expression of fatty acid binding protein 4 (FABP4), interleukin 10 (IL-10), catalase (CAT), cannabinoid receptor 1 (CNR1), and cannabinoid receptor 2 (CNR2) compared with CTL placenta. Gene expression of ECS-enzyme FA-amide hydrolase (FAAH) was lower in FLX and FO than in CTL. Proteomic analysis identified 3,974 proteins; of these, 51–59 were differentially abundant between treatments (P ≤ 0.05, |fold change| ≥ 1.5). Top canonical pathways enriched in FLX vs. CTL and in FO vs. CTL were triglyceride metabolism and inflammatory processes. Both n-3 FA increased the placental abundance of FA binding proteins (FABPs) 3 and 7. The abundance of CNR1 cannabinoid-receptor-interacting-protein-1 (CNRIP1) was reduced in FO vs. FLX. In silico modeling affirmed that bovine FABPs bind to endocannabinoids. The FLX increased the abundance of inflammatory CD44-antigen and secreted-phosphoprotein-1, whereas prostaglandin-endoperoxide synthase 2 was decreased in FO vs. CTL placenta. Maternal FO enriched neonatal plasma with n-3 FAs, and both FLX and FO reduced interleukin-6 concentrations compared with CTL.ConclusionMaternal n-3 FA from FLX and FO differentially affected the bovine placenta; both enhanced lipid metabolism and modulated oxidative stress, however, FO increased some transcriptional ECS components, possibly related to the increased FABPs. Maternal FO induced a unique balance of pro- and anti-inflammatory components in the placenta. Taken together, different sources of n-3 FA during late pregnancy enhanced placental immune and metabolic processes, which may affect the neonatal immune system.

Trace element concentrations in blood samples from dairy cows with uterine torsion and their neonatal calves.

Mineral deficiencies can lead to dystocia and abnormalities in neonates. Stillbirth of neonatal calves in dairy cows due to dystocia has become an economic problem. Uterine torsion (UT) is a common form of dystocia observed in dairy cows. However, to the best of our knowledge, there have been no reports on the characteristics of serum trace element concentrations in dairy cows with UT. This study aimed to comprehensively measure serum trace element concentrations in dairy cows with UT and dystocia. Dairy cows with (n = 15) and without (n = 27) UT and neonates (n = 9 and n = 26, respectively) were included in this study. Blood samples (10 mL) were collected, and serum trace element concentrations were evaluated using inductively coupled plasma mass spectrophotometry. The mortality rate at birth was significantly higher in calves delivered by cows with UT than those delivered by cows without UT. The odds ratio for mortality rate at birth in dairy cows with UT was 7.85. Serum zinc (Zn) levels were significantly lower in cows with UT than in cows without UT (p = 0.01). The copper: Zn ratio was significantly higher in cows with UT than in cows without torsion (p = 0.05). In contrast, serum Cobalt (Co) concentrations were significantly higher in neonates from cows with UT than in neonates from cows without UT (p = 0.01). Uterine torsion is associated with a high mortality rate at birth and considerable economic losses. Cows with UT had low serum Zn levels, and neonates born to these cows had high serum Co levels.

Near-infrared spectroscopy analysis of blood plasma for predicting nonesterified fatty acid concentrations in dairy cows

During the transition period, dairy cows are often exposed to negative energy balance (NEB), leading to lipid mobilization from adipose tissue into nonesterified fatty acids (NEFA), a common indicator of heightened illness risk. This study aimed to use blood near-infrared (NIR) spectra data to classify NEB into high or low categories, based on early-lactation cow NEFA thresholds. We collected a total of 186 plasma samples from 100 Holstein cows. The samples were categorized into critical thresholds, based on previous literature, of ≥0.60 and ≥0.70 mEq/L for identifying high NEB. Spectral data were preprocessed before the development of the predictive modes, which included the implementation of multiplicative scatter correction, standard normal variate (SNV), and first and second derivatives. The classification was performed using partial least square discriminant analyses (PLS-DA), and predictive performance was assessed using leave-one-out cross-validation. Predictive quality for each class was evaluated through specificity, precision, sensitivity, and F1 score. The study showed promising results, with the SNV technique achieving higher F1 scores. The model found 72.7% specificity, 78.9% precision, 80.8% sensitivity, and 79.8% F1 score to classify animals with NEFA levels of ≥0.60 mEq/L, and 82.1% specificity, 78.7% precision, 80.8% sensitivity, and 79.7% F1 score to classify animals with NEFA levels ≥0.70 mEq/L. These results indicate that NIR spectroscopy could serve as a tool for detecting cows under severe NEB, also showing potential for broader application across the entire transition period, as the spectral signal carried relevant information regarding cow metabolism. Furthermore, the combination of predictors derived from plasma spectra and other cow-level information can lead to more accurate disease alerts, given their relationship with the NEB.

Estradiol Concentrations During Estrous in Dairy Cattle and Its Association with Pregnancy and Genotype Diversity

This study determined estradiol concentrations during estrous in dairy cattle and its association with pregnancy and genotype diversity. A total of fifteen female dairy cows that had been identified with their genotype type using the PCR-RFLP method on follicle-stimulating hormone receptor (FSHR) and prolactin (PRL) genes were used in this study. The parameters measured were serum estrogen concentrations during estrous, estrous intensity, and pregnancy. Estradiol concentrations were analyzed by the enzyme-linked immunosorbent assay (ELISA) method. The data were analyzed using a general linear model procedure in the SAS program. The results showed that the average estradiol concentrations in dairy cows during estrous were 60.06±33.25 pg/ml. There was no difference (P>0.05) in estradiol concentrations in different classifications of age, body condition score (BCS), and estrous intensity. Estradiol concentrations in the group that showed success in post-insemination pregnancy were higher and significantly different (P<0.05) from the non-pregnant group. Differences in genotype variations of the FSHR and PRL genes had no significant effect (P>0.05) on the estradiol concentrations. In conclusion, estradiol concentrations during estrous were not associated with age, BCS, estrous intensity, and genotype diversity of FSHR and prolactin genes but were associated with pregnancy.

Preoperative protocol for right flank laparotomy affects postoperative serum cortisol concentrations in dairy cows.

To evaluate analgesic efficacy of 3 different preoperative protocols in cows undergoing right flank laparotomy for displaced abomasum. 40 cows diagnosed with displaced abomasum. The cows were assigned by block randomization to 1 of 3 preoperative protocols: inverted L-block using 50 mL of 2% lidocaine (ILB; n = 13), ILB plus preoperative flunixin meglumine (2 mg/kg, IV; ILB-F; 13), and dorsolumbar epidural anesthesia using 2% xylazine (0.8 mL) and 2% lidocaine (4 mL; EPI; 14). Venous blood samples were collected for CBC, serum biochemistry, and cortisol preoperatively and at 0 (immediately after), 3, 17, and 48 hours postoperatively. The mean (95% CI) of the serum cortisol in ILB, ILB-F, and EPI were 108.7 (66.7 to 150.7), 150.7 (116.4 to 185.0), and 139.8 (93.4 to 186.3), respectively. The serum cortisol concentrations decreased over time in all groups (ILB, P = .001; ILB-F and EPI, P < .001). In the ILB group, the cortisol concentration at 17 and 48 hours postoperatively decreased (P = .026 and P = .009, respectively), compared with that preoperatively. In the ILB-F and EPI groups, the preoperative cortisol concentration was the highest and then decreased at 0, 3, 17, and 48 hours postoperatively (ILB-F, 0 hours [P = .001] and 3, 17, and 48 hours [P < .001]; EPI, all [P < .001]). ILB-F and EPI improved intraoperative and immediate postoperative indicators of pain-related stress when compared to standard ILB. EPI requires less anesthetic, which may be beneficial when in short supply.

Relationship between periparturient diseases, metabolic markers and the dynamics of hair cortisol concentrations in dairy cows

Hair cortisol concentration (HCC) might represent a promising marker for retrospective welfare assessment of dairy cows. The objective of the study was to explore the dynamics of HCC in diseased and healthy cows from eight-week ante partum (AP) to eight-week post partum (PP). Twenty-four pregnant cows were followed from drying off to week eight PP. Tail hair was used to measure cortisol at five different time points. The occurrence of peripartum diseases, lameness and the body condition score (BCS) were monitored on a weekly basis. Blood β-hydroxybutyric acid, non-esterified fatty acids, calcium and insulin-like growth factor-1 (IGF-1) concentrations were measured. The temperature-humidity index (THI) was continuously recorded.The median values of HCC in all cows were 0.4, 0.3, 0.6, 0.8 and 0.5 pg/mg at weeks eight, four AP, calving, weeks four, eight PP, respectively. There was no association between HCC and the occurrence of peripartum diseases (P ≥ 0.05). A positive correlation between HCC and BCS loss (P < 0.01) and THI (P < 0.05) was observed. The occurrence of peripartum diseases was associated with low IGF-1 during the study period but no relationship was found between cortisol and IGF-1 levels (P ≥ 0.05). Brown Swiss cows showed higher HCC (P < 0.01) at weeks eight, four AP, and week four PP and lower average milk yield (P < 0.05) than Holstein–Friesian cows. In conclusion, HCC was not a suitable marker for peripartum diseases but it could reflect a stress response, which is linked to BCS loss, heat stress and breed.

Changes of acute-phase proteins, glucose, and lipid metabolism during pregnancy in lactating dairy cows.

The study aimed to evaluate the effects of different stages of lactation (0 to 300 d) and pregnancy (0 to 180 d) on serum amyloid A (SAA), C-reactive protein (CRP), glucose, total cholesterol (TCho), and triglyceride (TG) concentrations in dairy cows of different breeds. Thus, 40 healthy multiparous cows (10 Holstein, 10 Simmental, 10 Brown, and 10 Modicana) were randomly selected, and blood samples were collected once every 60 d for 1 year. Overall, SAA and CRP serum concentrations progressively increased and became more variable along the lactation, peaking at 240-300 d, and then decreased in the last period ( 300 d). Along pregnancy, SAA and CRP initially increased, with the highest concentrations at 60-120 d, and then decreased until the last phase of pregnancy ( 180 d). However, lactation and gestation phases did not significantly affect SAA and CRP when all the cows were analyzed together. A significant and positive correlation was observed between SAA and CRP both along lactation ( ; ) and pregnancy ( ; ). Breeds only showed differences in CRP levels along gestation ( ), due to a peak registered at 0-60 d in Holstein cows. In pregnant cows, glucose was positively correlated with SAA ( ; ) and CRP ( ; ). Hence, these significant and positive relationships reflect the physiological adaptations of the dairy cows along both gestational and lactational dynamics, suggesting that these proteins may also be involved in non-pathological processes. In this perspective, this study established that the obtained response markedly varies among healthy individuals along lactation and gestation and thus that the physiological range of acute-phase proteins (APPs) is wide; this makes it difficult to use these proteins as a marker of different physiological reproductive and productive periods.

Plasma Proteomic Profiling Reveals the Regulatory Factors of Milk Protein Synthesis in Holstein Cows.

Simple SummaryWe aimed to determine the plasma bio-markers of cows with high long-term milk protein concentration and investigate the mechanism of plasma proteins in milk protein synthesis. Some plasma proteins are considered to be related to milk protein synthesis. However, the characteristics of these proteins with different long-term milk protein concentrations are not fully elucidated. In this study, we collected milk protein concentration data of Holstein cows for 10 months on a commercial farm. Three groups of cows (n = 10 per group) with low, medium, and high milk protein concentrations were selected. We found that cows with high milk protein concentration had higher glucose, insulin-like growth factor 1, prolactin, insulin, and growth hormone concentrations than cows with low milk protein concentration. A total of 91 differentially expressed proteins were identified between cows with high and low milk protein concentrations by plasma proteomic. Furthermore, β-casein level and mammalian rapamycin target protein pathway in bovine mammary epithelial cells were enhanced by insulin-like growth factor 1 treatment. Our findings revealed that the differences in plasma proteins in cows with different milk protein concentrations and determined that β-casein synthesis was increased via the mammalian rapamycin target protein pathway following IGF-1 treatment in vitro.Milk protein concentrations in dairy cows are considered to be related to some plasma biomolecules. However, the characteristics of plasma biomolecules in dairy cows with different long-term milk protein concentrations are not fully elucidated. This study was conducted to understand the mechanism of plasma proteins in milk protein synthesis by the comparative analysis of the plasma proteomics of cows with different milk protein concentrations. Three groups of Holstein cows (per group = 10) with low (LMP), medium (MMP), and high long-term milk protein concentrations (HMP) were selected for the experiment to determine plasma hormones, biochemical parameters, and proteome. We found that HMP cows had higher concentrations of plasma insulin-like growth factor 1 (IGF-1), glucose, prolactin, insulin, and growth hormone than LMP cows. Additionally, plasma proteomic identified 91 differential proteins, including IGF-1 between the LMP and HMP groups, and the mTOR pathway was enriched. In vitro, IGF-1 treatment increased β-casein expression and simultaneously activated S6K1 and mTOR phosphorylation in bovine mammary epithelial cells. Taken together, these data demonstrate the differences in plasma hormones, biochemical parameters, and proteome of cows with different milk protein concentrations and indicate that IGF-1 enhanced milk protein synthesis, associated with activation of the mTOR signaling pathway.

O7 The effects of prepartum concentrate feeding on feed intake, energy balance and plasma acute phase protein concentrations in dairy cows

O7 The effects of prepartum concentrate feeding on feed intake, energy balance and plasma acute phase protein concentrations in dairy cows

Preliminary study on the effect of season on urinary analytes in healthy Italian dairy cows.

BackgroundSeason is known to affect serum analyte concentrations in dairy cows, and the same can be hypothesized for urinary analytes, but information in this regard is lacking.ObjectivesThe aim of the study was to assess the effect of seasonality on urinary variables in healthy dairy cows.MethodsTwelve Italian Holstein cows were randomly selected from a local herd, and urine specimens were collected once in each season of the year. For each cow, the lactation stage at each sampling time was also registered (lactation vs dry period), and physical examination and hematology and serum biochemistry measurements were used to assess health status. Three cows were voluntarily culled from the herd during the year; therefore, nine cows were included. Concentrations of urinary analytes recorded in each season for each cow were compared.ResultsSeasonality affected urinary protein‐to‐creatinine ratios (P = 0.012) with lower median values in summer compared with spring (P = 0.020) and autumn (P = 0.004); differences were also found in urinary sodium‐to‐urinary creatinine ratio (P = 0.009), with lower medians in summer compared with spring (P = 0.003) and autumn (P = 0.020). The direct consequences of higher summer temperatures and the acclimation strategies needed to adapt to this environment could explain the changes in urinary analytes that were recorded in the current study; in fact, decreased food and water consumption tend to increase urinary creatinine concentrations and decrease renal excretion of proteins and electrolytes.ConclusionsThe present results suggest that seasonality can affect urinary variables of healthy dairy cows.

Effect of different dry period duration on milk components and serum metabolites, and their associations with the first conception rate in multiparous Holstein dairy cows

The aims of the present study were to evaluate the effects of different dry period (DP) lengths on milk fat to protein ratio (FPR) and metabolic status – blood leptin, adiponectin and non-esterified fatty acids (NEFA) concentrations in dairy cows, and their associations with the result of the first timed artificial insemination (TAI). Cows were blocked either to short DP (SDP; 30±2 days; n=72) or conventional DP (CDP; 60±2 days; n=76). Milk FPR was calculated at 30 and 60 days in milk (DIM). Body condition score (BCS) was recorded at –60, –30, calving, and 60 DIM. Blood samples were obtained at –60, –30, –7, calving, +7, +30, and +60 DIM for serum metabolites measurement. TAI was implemented between 65–75 DIM for all cows. Milk FPR and its changes were statistically analysed using an independent sample t test. To assess the impact of time, the pattern of BCS, and serum metabolites on the result of the first AI, repeated measure ANOVA was used. Only FPR-30 DIM revealed significant difference between pregnant and non-pregnant cows in SDP group (P&lt;0.01). Reduced BCS loss was observed in the SDP group and followed by slightly higher probability of pregnancy at first AI (P=0.19). Leptin was not altered by shortening the DP (P≥0.1). Significant differences were observed in blood adiponectin prepartum (P&lt;0.001) and at +7 DIM (P&lt;0.01), as well as in NEFA at +7 and +30 DIM between the two groups (P&lt;0.05). Pregnant cows following the first AI had significantly high postpartum leptin concentrations (P&lt;0.05), high prepartum adiponectin (P≤0.001), and lower NEFA at +7 DIM (P&lt;0.01) in the SDP group. In conclusion, shortening the dry period caused reduced BCS loss postpartum and variations in serum metabolits that favoured the possibility of pregnancy at first AI.

Early Warning for Ovarian Diseases Based on Plasma Non-esterified Fatty Acid and Calcium Concentrations in Dairy Cows.

Inactive ovaries (IO) and ovarian (follicular or luteal) cysts (FC or LC) are two common ovarian diseases leading to infertility in dairy cattle. Both disorders are associated with altered metabolites and hormones. There are currently no known effective biomarkers that can be used for early diagnosis of ovarian diseases. The purpose of this study was to identify the plasma biomarkers of ovarian diseases in Holstein dairy cows that facilitate an early diagnosis of the diseases and control its progression. The experiment was performed from 3 weeks postpartum and last for 7 weeks. Seventy-six multiparous Holstein cows (mean age, 4.36 years; weight, 635.63 kg) were divided into healthy control group (HC, n = 22), FC group (n = 18), LC group (n = 18) and IO group (n = 18) by rectal palpation or ultrasonography during the last 2 weeks before trial end. Blood was collected via tail vein for measurement of plasma energy metabolites, liver function indicators, minerals, and hormones at 3 and 8 weeks postpartum. Data were analyzed by Mann-Whitney U, Kruskal-Wallis, Spearman correlation, binary logistic regression analysis and receiver operating characteristic analysis, where applicable. At 8 weeks postpartum, FC cows had a more severe body condition score loss and these had greater levels of non-esterified fatty acids (NEFA) and estradiol, and lesser levels of alanine aminotransferase (ALT), progesterone and insulin-like growth factor 1 (IGF-1) levels than HC cows (P < 0.05). LC cows had a lower milk yield, higher NEFA and progesterone levels, and lower calcium, phosphorus and magnesium levels than HC cows (P < 0.05). IO cows had a lower body condition score, higher NEFA levels, and lower ALT, calcium, phosphorus, magnesium, estradiol, progesterone and IGF-1 levels than HC cows (P < 0.05). At 3 weeks postpartum, cows with ovarian diseases had greater (P < 0.05) concentrations of NEFA, and lesser concentrations of ALT, calcium, phosphorus and IGF-1 than HC cows. Early warning values for ovarian diseases were plasma NEFA concentrations >0.50 mmol/L, or calcium concentrations <2.02 mmol/L. Therefore, plasma NEFA and calcium could be used as early-warning indicators for ovarian diseases in dairy cows.

Lactational performance and plasma and muscle amino acid concentrations in dairy cows fed diets supplying 2 levels of digestible histidine and metabolizable protein

The objective of this experiment was to investigate the effect of dietary levels of digestible histidine (dHis) and MP on lactational performance and plasma and muscle concentrations of free AA in dairy cows. A randomized block design experiment was conducted with 48 Holstein cows, including 20 primiparous, averaging (±SD) 103 ± 22 d in milk and 45 ± 9 kg/d milk yield at the beginning of the experiment. A 2-wk covariate period preceded 12 experimental wk, of which 10 wk were for data and sample collection. Experimental treatments were (1) MP-adequate (MPA) diet with 2.1% dHis of MP (MPA2.1), (2) MPA with 3.0% dHis (MPA3.0), (3) MP-deficient (MPD) diet with 2.1% dHis (MPD2.1), and (4) MPD with 3.0% dHis (MPD3.0). Actual dHis supply was estimated at 64, 97, 57, and 88 g/d, respectively. Diets supplied MP at 110% (MPA) and 96% (MPD) of NRC 2001 dairy model requirements calculated based on DMI and production data during the experiment. Dry matter intake and milk yield data were collected daily, milk samples for composition and blood samples for AA analysis were collected every other week, and muscle biopsies at the end of covariate period, and during wk 12 of the experiment. The overall DMI was not affected by dHis or MP level. Milk yield tended to be increased by 3.0% dHis compared with 2.1% dHis. Milk true protein concentration and yield were not affected by treatments, whereas milk urea nitrogen concentration was lower for MPD versus the MPA diet. Milk fat concentration was lower for MPD versus MPA. There was a MP × dHis interaction for milk fat yield and energy-corrected milk; milk fat was lower for MPD3.0 versus MPD2.1, but similar for cows fed the MPA diet regardless of dHis level whereas energy-corrected milk was greater for MPA3.0 versus MPA2.1 but tended to be lower for MPD3.0 versus MPD2.1. Plasma His concentration was greater for cows fed dHis3.0, and concentration of sum of essential AA was greater, whereas carnosine, 1-Methyl-His and 3-Methyl-His concentrations were lower for cows fed MPA versus MPD diet. Muscle concentration of His was greater for cows fed dHis3.0 treatment. The apparent efficiency of His utilization was increased at lower MP and His levels. Overall, cows fed a corn silage-based diet supplying MP at 110% of NRC (2001) requirements tended to have increased ECM yield and similar milk protein yield to cows fed a diet supplying MP at 96% of requirements. Supplying dHis at 3.0% of MP (or 86 and 96 g/d, for MPD3.0 and MPA3.0, respectively) tended to increase milk yield and increased plasma and muscle concentrations of His but had minor or no effects on other production variables in dairy cows.

Effects of feeding rumen-protected methionine pre- and postpartum in multiparous Holstein cows: Lactation performance and plasma amino acid concentrations

Objectives were to evaluate the effect of feeding rumen-protected methionine (RPM) in pre- and postpartum total mix ration (TMR) on lactation performance and plasma AA concentrations in dairy cows. A total of 470 multiparous Holstein cows [235 cows at University of Wisconsin (UW) and 235 cows at Cornell University (CU)] were enrolled approximately 4 wk before parturition, housed in close-up dry cow and replicated lactation pens. Pens were randomly assigned to treatment diets (pre- and postpartum, respectively): UW control (CON) diet = 2.30 and 2.09% of Met as percentage of metabolizable protein (MP) and RPM diet = 2.83 and 2.58% of Met as MP; CU CON = 2.22 and 2.19% of Met as percentage of MP, and CU RPM = 2.85 and 2.65% of Met as percentage of MP. Treatments were evaluated until 112 ± 3 d in milk (DIM). Milk yield was recorded daily. Milk samples were collected at wk 1 and 2 of lactation, and then every other week, and analyzed for milk composition. For lactation pens, dry matter intake (DMI) was recorded daily. Body weight and body condition score were determined from 4 ± 3 DIM and parturition until 39 ± 3 and 49 DIM, respectively. Plasma AA concentrations were evaluated within 3 h after feeding during the periparturient period [d -7 (±4), 0, 7 (±1), 14 (±1), and 21 (±1); n = 225]. In addition, plasma AA concentrations were evaluated (every 3 h for 24 h) after feeding in cows at 76 ± 8 DIM (n = 16) and within 3 h after feeding in cows at 80 ± 3 DIM (n = 72). The RPM treatment had no effect on DMI (27.9 vs. 28.0 kg/d) or milk yield (48.7 vs. 49.2 kg/d) for RPM and CON, respectively. Cows fed the RPM treatment had increased milk protein concentration (3.07 vs. 2.95%) and yield (1.48 vs. 1.43 kg/d), and milk fat concentration (3.87 vs. 3.77%), although milk fat yield did not differ. Plasma Met concentrations tended to be greater for cows fed RPM at 7 d before parturition (25.9 vs. 22.9 µM), did not differ at parturition (22.0 vs. 20.4 µM), and were increased on d 7 (31.0 vs. 21.2 µM) and remained greater with consistent concentrations until d 21 postpartum (d 14: 30.5 vs. 19.0 µM; d 21: 31.0 vs. 17.8 µM). However, feeding RPM decreased Leu, Val, Asn, and Ser (d 7, 14, and 21) and Tyr (d 14). At a later stage in lactation, plasma Met was increased for RPM cows (34.4 vs. 16.7 µM) consistently throughout the day, with no changes in other AA. Substantial variation was detected for plasma Met concentration (range: RPM = 8.9-63.3 µM; CON = 7.8-28.8 µM) among cows [coefficient of variation (CV) > 28%] and within cow during the day (CV: 10.5-27.1%). In conclusion, feeding RPM increased plasma Met concentration and improved lactation performance via increased milk protein production.

Influence of chelates on pigs productivity and quality

Influence of chelates on pigs productivity and quality

197 Effect of a SARA challenge diet on chewing behavior and rumino-reticular short chain fatty acid concentrations in dairy cows

Abstract Intensive dairy production systems encourage feeding of high-concentrate diets to increase milk production efficiency. However, there is limited information regarding the effect of a SARA challenge diet on chewing behavior and rumino-reticular short chain fatty acid (SCFA) concentration. The objective of this study was to evaluate chewing activity and SCFA production in the rumen and reticulum, using nine ruminally cannulated non-lactating Holstein cows. Preceding the trial, cows were transitioned from 100% forage to 65% DM concentrate over eight days. Trial day 1 began once cows reached 65% DM concentrate and monitoring during 23 days. RumiWatch halters were used to monitor chewing activity. SCFA analysis was conducted on rumen and reticulum fluid collected 4 hours after feeding using gas chromatography. Data were analyzed with SAS, with the fixed effect of days and cow as random effect. There was an increase in DM intake during the first four hours after feeding: 1.97 and 2.25 ± 0.12 kg for day 1 and 23, respectively (P &amp;lt; 0.05). There was no difference in rumination time (P = 0.16) with 29 ± 8.5 minutes during the first four hours of feeding. However, chewing index (P = 0.08) tended to decrease from 36.7 to 29.4 ± 4.4 minutes of chewing/kg of DM for day 1 and 23, respectively. Moreover, on day 1, propionate increased from 19.9 ± 1.02 to 20.1 ± 1.02% and from 24.04 ± 0.93 to 25.4 ± 1.02% compared to day 23 for rumen and reticulum, respectively (P &amp;lt; 0.05). In addition, from day 1 to day 23, the rumen and reticulum acetate/propionate ratio declined from 3.2 ± 0.15 and 3.1 ± 0.1, to 2.5 ± 0.15, respectively, and reticulum SCFA decreased from 87 to 67 µmol/g, respectively. Overall, there was no effect of the 23-day SARA challenge diet on chewing activity. However, there was a reduction of SCFA concentration in reticulum, which may be due to enhanced SCFA absorption or increased feed bolus neutralizing capacity.

Performance evaluation of a newly designed on-farm blood testing system for determining blood non-esterified fatty acid and β-hydroxybutyrate concentrations in dairy cows

The objective of this study was to evaluate a newly designed on-farm blood testing system (OFBTS) for monitoring blood concentrations of non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA) in dairy cows. Blood samples from 230 Holstein dairy cows between −86 and 343 days in milk were collected. A drop of whole blood was used to determine NEFA and BHBA using the OFBTS. Plasma from the remaining blood was used to determine both analytes using a commercial kit (gold standard). In the repeatability of the OFBTS, the intra-assay CV for NEFA and BHBA were 1.3% and 4.5%, and the inter-assay CV were 1.8% and 2.9%, respectively. The slope and coefficient of determination of OFBTS analysis of NEFA compared to the gold standard were 0.92 and 0.94. Those for BHBA were 0.94 and 0.98. Mean of the difference between the gold standard laboratory assays and OFBTS of NEFA and BHBA were 0.021 and 0.019, respectively. However, the bias became substantial for NEFA in the higher concentration ranges (>1.2 mEq/L). The sensitivity and specificity of NEFA were 93.2% and 99.4% at a cutpoint of 0.4 mEq/L, and 87.9% and 100% at 0.6 mEq/L. Those of BHBA were 86.2% and 99.0% at a cutpoint of 1.0 mM, and 94.7% and 99.5% at 1.2 mM. The reaction time for the NEFA to reach 0.6 mEq/L was 7 min. The BHBA reaction reached 1.2 mM within 2 min. In conclusion, the OFBTS has excellent performance for evaluating blood NEFA or BHBA concentrations.

Population physiologically based modeling of pirlimycin milk concentrations in dairy cows

Predictions of drug residues in milk are critical in food protection and are a major consideration in the economics of treatment of mastitis in dairy cows. Nonlinear mixed-effects modeling (NLME) has been advocated as a suitable pharmaco-statistical method for the study of drug residues in milk. Recent developments in physiologically based pharmacokinetic (PBPK) modeling of intramammary drugs allow the combination of a mechanistic description of milk pharmacokinetics with NLME methods. The PBPK model was applied to NLME analysis of a data set consisting of milk drug concentrations from 78 healthy cows and 117 with clinical mastitis. Pirlimycin milk pharmacokinetics were adequately described by the model across the range of observed concentrations. Mastitis was characterized by increased variance in milk production volume. Udder residual volume was larger in cows with 1, or 2 or greater diseased mammary glands than in the healthy cows. Low-producing cows had a greater risk of prolonged milk residues. With the exclusion of the low-production cows, the model predicted that healthy cows required a milk discard time 12 h longer than that indicated by the label, and the diseased cows 36 h longer than indicated by the label. More pirlimycin was systemically absorbed in the gram-positive infected compared with the gram-negative infected or healthy cows, suggesting a greater risk of violative meat residues in gram-positive infected cows. Using NLME and PBPK models, we identified factors associated with changes in pirlimycin milk residues that may affect food safety. This model extends the verification of a simple physiologically based framework for the study of intramammary drugs.

Mid-infrared spectroscopic analysis of raw milk to predict the blood nonesterified fatty acid concentrations in dairy cows

In high-yielding dairy cattle, severe postpartum negative energy balance is often associated with metabolic and infectious disorders that negatively affect production, fertility, and welfare. Mobilization of adipose tissue associated with negative energy balance is reflected through an increased level of nonesterified fatty acids (NEFA) in the blood plasma. Earlier, identification of negative energy balance through detection of increased blood plasma NEFA concentration required laborious and stressful blood sampling. More recently, attempts have been made to predict blood NEFA concentration from milk samples. In this study, we aimed to develop and validate a model to predict blood plasma NEFA concentration using the milk mid-infrared (MIR) spectra that are routinely measured in the context of milk recording. To this end, blood plasma and milk samples were collected in wk 2, 3, and 20 postpartum for 192 lactations in 3 herds. The blood plasma samples were taken in the morning, and representative milk samples were collected during the morning and evening milk sessions on the same day. To predict plasma NEFA concentration from the milk MIR spectra, partial least squares regression models were trained on part of the observations from the first herd. The models were then thoroughly validated on all other observations of the first herd and on the observations of the 2 independent herds to explore their robustness and wide applicability. The final model could accurately predict blood plasma NEFA concentrations <0.6 mmol/L with a root mean square error of prediction of <0.143 mmol/L. However, for blood plasma with >1.2 mmol/L NEFA, the model clearly underestimated the true level. Additionally, we found that morning blood plasma NEFA levels were predicted with significantly higher accuracy using MIR spectra of evening milk samples compared with MIR spectra of morning samples, with root mean square error of prediction values of, respectively, 0.182 and 0.197 mmol/L, and R2 values of 0.613 and 0.502. These results suggest a time delay between variations in blood plasma NEFA and related milk biomarkers. Based on the MIR spectra of evening milk samples, cows at risk for negative energy status, indicated by detrimental morning blood plasma NEFA levels (>0.6 mmol/L), could be identified with a sensitivity and specificity of, respectively, 0.831 and 0.800. As this model can be applied to millions of historical and future milk MIR spectra, it opens an opportunity for regular metabolic screening and improved resilience phenotyping.