Development and Validation of a Method for Hydrolysis and Analysis of Amino Acids in Ruminant Feeds, Tissue, and Milk Using Isotope Dilution Z-HILIC Coupled with Electrospray Ionization Triple Quadrupole LC-MS/MS

Current analytical methods for amino acid (AA) analysis in ruminant nutrition are time-consuming and expensive. This study aimed to develop a method for AA analysis that is faster, more efficient, rugged, and accessible. Four representative matrixes were selected for method development and validation: milk, tissue, feed, and soy flour standard reference material from National Institute of Standards and Technology. Acid and alkaline hydrolysis were used to analyze 18 AA. Separation of AA was performed using a Z-HILIC column in an 18-min run coupled to a triple quadrupole LC/MS system in positive and negative electrospray ionization for identification and quantitation. The method was evaluated for recovery, precision, calibration curve linearity, and limits of detection (LODs) and limits of quantitation (LOQs) and applied to other feed samples. Good quantitation results were achieved for all AA, with coefficients of determination (R2) over 0.995; LODs at 0.2-28.2 and LOQs at 0.7-94.1 ng/mL; intraday and interday precision <14.9% relative standard deviation; blank recovery between 75.6 and 116.2%; and sample recovery between 75.6 and 118.0%. Overall, AA concentrations were similar to literature values, and there was a tendency for higher N recovery as AA. In conclusion, an efficient and robust method was validated to routinely analyze AA for appropriate characterization in diet formulation for dairy cattle.

Predicting orthophosphate in feces and manure from dairy cattle

Dairy cattle excreta are a valuable source of orthophosphate (Ortho-P), an inorganic form of phosphorus (P) that is readily available for microorganisms, plant growth, and development. There is, however, a growing environmental concern about the potential negative environmental impact of excessive amounts of Ortho-P excretion, which can lead to the eutrophication of water bodies. As a result, the development of mathematical equations to quantify and manage Ortho-P excretion on dairy farms could prove valuable for environmental sustainability. This study aimed to use literature data to develop empirical predictions for Ortho-P (g/kg dry matter [DM]) excretion using total P (TP [g/kg DM]) content of dairy cattle feces (Ortho-Pf) and manure (Ortho-Pm). Data sets from studies that evaluated and characterized the different forms of P in feces and manure from dairy cattle were compiled. After outlier exclusion, the final retained database for feces included 37 treatment means from 4 published papers while the manure comprised 23 treatment means from 7 published papers. A linear-mixed model was used to develop the predictive equations, incorporating the random effect of the study. A leave-one-out cross-validation procedure was used to evaluate the predictive ability of the developed models, whereby studies were regarded as folds. The fecal equation was determined as Ortho-Pf (g/kg DM) = -2.447 (0.572) + 0.966 (0.083) × TP (g/kg DM) (R2 = 0.79) and resulted in a root mean square prediction error as a percentage of mean observed value (RMSPE, %) of 32.8% and error due to random sources of 97.6%. Additionally, the manure equation was determined as Ortho-Pm (g/kg) = -0.204 (0.446) + 0.590 (0.065) × TP (g/kg) (R2 = 0.77) and had an RMSPE of 43.3% with a random error of 93.9%. Both models revealed minimal mean and slope biases on feces and manure data. Findings suggest that these sets of equations can be used to estimate excreted Ortho-P from total excreted P, helping nutritionists and farmers to understand the impact of dietary P changes on the environment. Further, these equations can be incorporated into extant models such as the Cornell Net Carbohydrate and Protein System (CNCPS) to aid in understanding and mitigating P and Ortho-P excretion from dairy cattle and to clarify the portion of P that migrates more rapidly into watersheds.

Enteric Methane Emissions Prediction in Dairy Cattle and Effects of Monensin on Methane Emissions: A Meta-Analysis

Greenhouse gas emissions, such as enteric methane (CH₄) from ruminant livestock, have been linked to global warming. Thus, easily applicable CH₄ management strategies, including the inclusion of dietary additives, should be in place. The objectives of the current study were to: (i) compile a database of animal records that supplemented monensin and investigate the effect of monensin on CH₄ emissions; (ii) identify the principal dietary, animal, and lactation performance input variables that predict enteric CH₄ production (g/d) and yield (g/kg of dry matter intake DMI); (iii) develop empirical models that predict CH₄ production and yield in dairy cattle; and (iv) evaluate the newly developed models and published models in the literature. A significant reduction in CH₄ production and yield of 5.4% and 4.0%, respectively, was found with a monensin supplementation of ≤24 mg/kg DM. However, no robust models were developed from the monensin database because of inadequate observations under the current paper's inclusion/exclusion criteria. Thus, further long-term in vivo studies of monensin supplementation at ≤24 mg/kg DMI in dairy cattle on CH₄ emissions specifically beyond 21 days of feeding are reported to ensure the monensin effects on the enteric CH₄ are needed. In order to explore CH₄ predictions independent of monensin, additional studies were added to the database. Subsequently, dairy cattle CH₄ production prediction models were developed using a database generated from 18 in vivo studies, which included 61 treatment means from the combined data of lactating and non-lactating cows (COM) with a subset of 48 treatment means for lactating cows (LAC database). A leave-one-out cross-validation of the derived models showed that a DMI-only predictor model had a similar root mean square prediction error as a percentage of the mean observed value (RMSPE, %) on the COM and LAC database of 14.7 and 14.1%, respectively, and it was the key predictor of CH₄ production. All databases observed an improvement in prediction abilities in CH₄ production with DMI in the models along with dietary forage proportion inclusion and the quadratic term of dietary forage proportion. For the COM database, the CH₄ yield was best predicted by the dietary forage proportion only, while the LAC database was for dietary forage proportion, milk fat, and protein yields. The best newly developed models showed improved predictions of CH₄ emission compared to other published equations. Our results indicate that the inclusion of dietary composition along with DMI can provide an improved CH₄ production prediction in dairy cattle.

Effects of feeding rumen-protected methionine pre- and postpartum on reproductive outcomes of multiparous Holstein cows

Our primary objective was to evaluate the effect of feeding rumen-protected Met (RPM) in the pre- and postpartum total mixed ration (TMR) on pregnancy per artificial insemination (AI) and pregnancy loss in multiparous Holstein cows. We also evaluated multiple secondary reproductive physiological outcomes before and after AI, including uterine health, ovarian cyclicity, response to synchronization of ovulation, and markers of embryo development and size. A total of 470 multiparous Holstein cows [235 at the University of Wisconsin (UW) and 235 at Cornell University (CU)] were used for this experiment. Experimental treatment diets were applied at the pen level (2 and 4 close-up pens at CU and UW, respectively, and 12 and 6 postfresh pens at CU and UW, respectively); thus, pen was the experimental unit, and cow was the observational unit. Cows were enrolled and randomly assigned to be fed the experimental treatment diets at approximately 4 wk before parturition until 67 d of gestation [147 d in milk (DIM)] after their first service. Close-up dry cow and replicated lactation pens were randomly assigned to treatment diets: RPM, prepartum = 2.83% (UW) and 2.85% (CU), postpartum = 2.58% (UW) and 2.65% (CU); and control (CON), prepartum = 2.30% (UW) and 2.22% (CU), postpartum = 2.09% (UW) and 2.19% (CU; Met as percentage of metabolizable protein). Vaginal discharge and uterine cytology (percentage of polymorphonuclear leucocytes) were evaluated at 35 ± 3 DIM. Cows received timed AI (TAI) at 80 ± 3 DIM after synchronization of ovulation with the Double-Ovsynch protocol. Ovarian cyclicity status, response to synchronization of ovulation, and luteal function were determined by measuring circulating concentrations of progesterone at 35 and 49 ± 3 DIM, 48 and 24 h before TAI, and 8, 18, 22, 25, and 29 d after TAI. Interferon-stimulated gene expression in white blood cells were compared on 18 d after TAI (CU only) and pregnancy-specific protein B concentrations at 22, 25, 29, 32, and 67 d after TAI. Pregnancy status was determined using pregnancy-specific protein B at 25 and 29 d after TAI, and by transrectal ultrasonography at 32, 39, and 67 d after TAI. Embryo and amniotic vesicle size were determined at 32 and 39 d after TAI. Pregnancy per AI (25 d: 64.7 vs. 64.0%, 32 d: 54.3 vs. 55.1% for CON and RPM, respectively) and pregnancy loss (25 to 67 d: 22.6 vs. 19.2% for CON and RPM, respectively) for synchronized cows did not differ. The proportion of cows with purulent vaginal discharge (CON = 7.7 vs. RPM = 4.6%) and cytological endometritis (CON = 20.8 vs. RPM = 23.6%) did not differ. Cyclicity status, ovarian responses to the synchronization protocol, and synchronization rate also did not differ. In addition, fold change for interferon-stimulated genes, concentrations of pregnancy-specific protein B, and embryo size were not affected by treatments. In conclusion, feeding RPM in the pre- and postpartum TMR at the amounts used in this experiment did not affect uterine health, cyclicity, embryo development, or reproductive efficiency in dairy cows.

Effect of dietary supplementation of 2 forms of a B vitamin and choline blend on the performance of Holstein calves during the transition and postweaning phase

The transition from a liquid- to a solid-based diet involves several adaptations in calves. Development of ruminal function is likely to alter B vitamin and choline supply, although little is known about the extent of these changes relative to the calf's requirements and consequences for the calf around weaning. Moreover, literature data are equivocal concerning the need to supplement B vitamins and choline through weaning and transition phase of the dairy calf. To evaluate the effect of increasing B vitamin and choline supply on performance, 61 Holstein calves were individually housed and raised from birth to 13 wk of age. Calves were fed milk replacer (28% crude protein, 15% fat) up to 1.6 kg of dry matter (DM)/d at 15% solids (3 times/d) from birth to 4 wk of age. At that time, calves were randomly assigned to one of 3 treatments: a rumen-protected blend of B vitamins and choline (RPBV); a 30:70 mix of a nonprotected blend of B vitamins and choline and fat (UPBV); or fat only, used as control (CTRL). Calves were maintained on milk replacer and offered ad libitum quantities of a starter grain (25.5% crude protein) specifically formulated to supply all essential amino acids with no added B vitamins or choline. The supplements were provided in gel capsules and administered once a day to each calf in quantities corresponding to 0.39 and 0.28% of the previous day's starter DM intake for the vitamin blends and control, respectively. Calves were weaned gradually from d 49 to 63. Body weight and stature were measured, and blood was collected and analyzed for hematocrit, plasma urea nitrogen, β-hydroxybutyrate, folates, and vitamin B₁₂. Body weight and stature were similar among treatments. Overall gain (0.99 kg/d), DM intake (1.90 kg of DM/d), and feed efficiency (0.52) were not affected by vitamin supplementation. Plasma vitamin B₁₂ concentrations were not different between RPBV and UPBV but tended to be higher at the end of weaning and were greater postweaning in RPBV and UPBV treatments compared with CTRL. Both forms of the vitamin blend effectively improved vitamin B₁₂ status postweaning with no effect on folate status. No differences were observed in other blood measurements. Under conditions of this study, additional B vitamins and choline did not improve calf performance before, during, or after weaning.

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.

Effects of rumen-protected methionine or methionine analogs in starter on plasma metabolites, growth, and efficiency of Holstein calves from 14 to 91 d of age

During weaning, methionine (Met) supply decreases as liquid feed intake is reduced and ruminal function is developing. During this transition, the calf starter should both promote ruminal development and provide adequate nutrients post-ruminally. In mature ruminants, rumen-protected Met (RPM) and the Met analogs, 2-hydroxy-4-(methylthio)-butanoic acid (HMTBa) and HMTBa isopropyl ester (HMBi), are used to increase Met supply, stimulate ruminal fermentation, or exert both effects, respectively. To evaluate the effects of these forms of Met on calf performance during development of ruminal function, 74 Holstein calves were raised until 91 d of age, in 2 enrollment periods. Calves were individually housed from birth and, at 14 d of age, balanced for sex and randomly assigned to receive a starter with no added Met (CTRL, n = 20) or one supplemented with RPM (Smartamine M, Adisseo USA Inc., Alpharetta, GA; n = 16), HMTBa (RumenSmart, Adisseo; n = 19), or HMBi (MetaSmart, Adisseo; n = 19). Milk replacer [28% crude protein (CP), 15% fat] was offered up to 1.6 kg of dry matter (DM)/d and fed 3 times daily. Weaning was facilitated from d 49 to 63. The 4 starters (25% CP, 2.5 Mcal of metabolizable energy/kg of DM) were offered ad libitum, and supplement inclusion was set to provide an additional 0.16% DM of Met equivalents, and equal amounts of HMTBa within the analogs. Body weight and stature were measured, and blood was collected and analyzed for plasma urea nitrogen, β-hydroxybutyrate, and free AA on a weekly basis. Supplementation of RPM and HMBi increased free plasma Met, but no differences in growth or feed efficiency compared with calves fed the CTRL starter could be attributed to the additional Met supply alone. The addition of HMBi in the starter increased feed intake and body weight during the last weeks of the experiment. On the contrary, HMTBa failed to increase plasma Met and depressed intake and growth after weaning, likely because the level included in the diet was too high and intake was greater than previous studies, exacerbating the level of HMTBa ingested. No differences were observed in stature, feed efficiency, or non-AA plasma measurements among groups. These results demonstrate that RPM and HMBi are effective sources of metabolizable Met; however, Met was apparently not limiting calves fed the basal diet in this study. The increased feed intake observed with the inclusion of HMBi in the starter during the weaning and early postweaning period might be mediated by its metabolism in the rumen, and further research is needed to determine the mechanisms involved.

Optimal harvest timing for brown midrib forage sorghum yield, nutritive value, and ration performance

Forage sorghum [Sorghum bicolor (L.) Moench] is a viable alternative to corn silage (Zea mays L.) in double cropping rotations with forage winter cereals in New York due to a later planting date and potentially earlier harvest date of forage sorghum than is typical for corn silage. Our objective was to determine whether harvest of brachytic dwarf brown midrib forage sorghum can take place before the currently recommended soft dough harvest time while maintaining dry matter (DM) yield, forage nutritive value, and total mixed ration performance. Seven trials were conducted on 2 research farms in central New York from 2014 to 2017. Forage sorghum received 1 of 2 fertilizer N rates at planting (112 and 224 kg of N/ha). Stands were harvested at boot, flower, milk, and soft dough stages. Forage samples were analyzed for nutritive value and substituted for corn silage in a typical dairy total mixed ration at varying amounts using the Cornell Net Carbohydrate and Protein System. Timing of harvest affected yield and forage nutritive value for each individual trial and across trials, and the effects were independent of N fertilizer application rate. Averaged across trials, yield ranged from 10.7 Mg of DM/ha for the boot stage to 13.5, 15.2, and 15.8 Mg of DM/ha for the flower, milk, and soft dough stages, respectively. For individual trials, yield either remained constant with harvest beyond the flower stage (4 trials), or beyond the milk stage (1 trial), whereas for 2 trials yield increased up to the soft dough stage. At the later harvest stages, DM, starch, and nonfiber carbohydrates were increased, whereas crude protein, neutral detergent fiber, and 30-h neutral detergent fiber digestibility were decreased. Without adjusting for DM intake, substitution of corn silage by forage sorghum harvested at the soft dough stage resulted in stable predicted metabolizable energy allowable milk, whereas the reduced starch content of earlier harvested sorghum resulted in less metabolizable energy allowable milk with greater substitution of corn silage for sorghum. Forage sorghum can be harvested as early as the flower or milk stage without losing DM yield, allowing for timely planting of forage winter cereal in a double cropping rotation. However, energy supplementation in the diet is needed to make up for reduced starch concentrations with harvest of sorghum at flower and milk growth stages.

ASN-ASAS SYMPOSIUM: FUTURE OF DATA ANALYTICS IN NUTRITION: Modeling complex problems with system dynamics: applications in animal agriculture1

Many problematic outcomes in agricultural and food systems have important dynamic dimensions and arise due to underlying system structure. Thus, understanding the linkages between system structure and dynamic behavior often is important for the design and implementation of interventions to achieve sustained improvements. System dynamics (SD) modeling represents system structure using stock-flow-feedback structures expressed as systems of differential equations solved by numerical integration methods. System dynamics methods also encompass a broader methodological approach that emphasizes model structural development and data inputs to replicate one of a limited number of problematic behavioral modes, anticipates dynamic complexity, and focuses on feedback processes arising from endogenous system elements. This paper highlights the process of SD modeling using 2 examples from animal agriculture at different scales. A dynamic version of the Cornell Net Carbohydrate and Protein System (CNCPS) that represents outcomes for an individual dairy cow is formulated as an SD model illustrates the benefits of the SD approach in modeling rumen fill and animal performance. At a very different scale, an SD model of the Brazilian dairy supply chain (farms, processing, and consumers) illustrates the country-level impacts of efforts to improve cow productivity and how impacts differ if productivity improvement occurs on small farms rather than large farms. The paper concludes with recommendations about how to increase awareness and training in SD methods to enhance their appropriate use in research and instruction.

Nutrient supply alters transcriptome regulation in adipose tissue of pre-weaning Holstein calves

Performance of dairy cows can be influenced by early life nutrient supply. Adipose tissue is diet sensitive and an important component in that process as it is involved in the regulation of energetic, reproductive and immunological functions. However, it is not clear how early life nutrition alters the molecular regulation of adipose tissue in calves and potentially adult individuals. This study aimed at determining how differences in pre-weaning nutrient supply alter gene expression profiles and physiology in omental adipose tissue. A total of 12 female Holstein calves were fed two levels of milk replacer supply: a restricted amount of 11.72 MJ of metabolizable energy (ME) intake per day (n = 6) or an enhanced amount of 1.26 MJ ME intake per kg of metabolic body weight (BW^0.75), resulting in supply from 17.58 to 35.17 MJ ME intake per day (n = 6). All calves had ad libitum access to a commercial calf starter and water. Analysis of the transcriptome profiles at 54 ± 2 days of age revealed that a total of 396 out of 19,968 genes were differentially expressed (DE) between groups (p < 0.001, FDR < 0.1). The directional expression of DE genes through Ingenuity Pathway Analysis showed that an enhanced nutrient supply alters adipose tissue physiology of pre-weaned calves. Several biological functions were increased (Z-score > +2), including Lipid Metabolism (Fatty Acid Metabolism), Cell Cycle (Entry into Interphase, Interphase, Mitosis and Cell Cycle Progression), Cellular Assembly and Organization (Cytoskeleton Formation and Cytoplasm Development) and Molecular Transport (Transport of Carboxylic Acid). These changes were potentially orchestrated by the activation/inhibition of 17 upstream regulators genes. Our findings indicate that adipose tissue of calves under an enhanced nutrient supply is physiologically distinct from restricted calves due to an increased development/expansion rate and also a higher metabolic activity through increased fatty acid metabolism.

Effect of nutritional plane on health and performance in dairy calves after experimental infection with Cryptosporidium parvum

OBJECTIVE

To evaluate the effect of nutritional plane on health and performance of dairy calves after infection with Cryptosporidium parvum.

DESIGN

Randomized, controlled trial.

ANIMALS

20 Holstein bull calves.

PROCEDURES

Calves were assigned to a higher plane of nutrition (HPN; 0.30 Mcal intake energy/kg of metabolic body weight using a 28% protein-20% fat milk replacer) or conventional nutrition (CN; 0.13 Mcal intake energy/kg of metabolic body weight using a 20% protein-20% fat milk replacer). Calves were inoculated with C parvum oocysts at 3 days old. Fecal and health scores, oocyst counts, weight gain, dry matter intake, and hematologic variables were measured for 21 days. Data were analyzed with nonparametric and regression methods. Results-Body weight (day 1), serum total protein concentration (day 3), and PCV (day 3) were not different between groups. Oocyst shedding was not different between groups. The PCV was higher in the CN group (40%), compared with the HPN group (32%) at the end of the study. Fecal scores (FS) improved faster in the HPN group (median, -0.1 FS/feeding), compared with the CN group (median, -0.06 FS/feeding). The HPN calves had better average daily gain (ADG) than did CN calves (median, 433 g/d vs -48 g/d, respectively). Feed efficiency (ADG:dry matter intake ratio) was better for HPN calves than CN calves (median, 131.9 g/kg vs -31.4 g/kg).

CONCLUSIONS AND CLINICAL RELEVANCE

After a pathogen challenge, calves maintained hydration, had faster resolution of diarrhea, grew faster, and converted feed with greater efficiency when fed a higher plane of nutrition.

Identification of estrogen-responsive genes in the parenchyma and fat pad of the bovine mammary gland by microarray analysis

Identification of estrogen-responsive genes is an essential step toward understanding mechanisms of estrogen action during mammary gland development. To identify these genes, 16 prepubertal heifers were used in a 2 × 2 factorial experiment, with ovarian status (intact or ovariectomized) as the first factor and estrogen treatment as the second (control or estradiol). Heifers were ovariectomized at ∼4.5 mo of age, and estrogen treatments were initiated 1 mo later. After 3 days of treatment, gene expression was analyzed in the parenchyma and fat pad of the bovine mammary gland using a high-density oligonucleotide microarray. Oligonucelotide probes represented 40,808 tentative consensus sequences from TIGR Bos taurus Gene Index and 4,575 singleton expressed sequence tags derived from libraries of pooled mammary gland and gut tissues. Microarray data were analyzed by use of the SAS mixed procedure, with an experiment-wide permutation-based significance level of P < 0.1. Considerable differences in basal gene expression were noted between mammary parenchyma and fat pad. A total of 124 estrogen-responsive genes were identified, with most responding only in the parenchyma or the fat pad. The majority of genes identified were not previously reported to be estrogen responsive. These undoubtedly include genes that are regulated indirectly but also include known estrogen-targeted genes and novel genes with potential estrogen-responsive elements in their promoter regions. The distinctive expression patterns regulated by estrogen in parenchyma and fat pad shed light on the need for both tissues to obtain normal mammary development.