James K. Drackley

This research article reports an investigation of the associations among hypocalcemia types at calving, metabolic diseases, milk production, and milk composition in Holstein cows. A total of 100 Holstein-Friesian dairy cows (31 primiparous and 69 multiparous cows) from 4 farms were evaluated at multiple time points postpartum. The cows were categorized into 4 groups: Normocalcemic (NC): primiparous: [Ca] > 8.6 mg/dL at 1 and 2 d in milk (DIM), multiparous: [Ca] > 7.08 mg/dL at 1 DIM and >8.8 mg/dL at 4 DIM; Transient Subclinical Hypocalcemia (tSCH): primiparous: [Ca] ≤ 8.6 mg/dL at 1 DIM and >8.6 mg/dL at 2 DIM, multiparous: [Ca] ≤ 7.08 mg/dL at 1 DIM and >8.8 mg/dL at 4 DIM; Persistent Subclinical Hypocalcemia (pSCH): primiparous: [Ca] ≤ 8.6 mg/dL at 1 and 2 DIM, multiparous: [Ca] ≤ 7.08 mg/dL at 1 DIM and ≤8.8 mg/dL at 4 DIM; and Delayed Subclinical Hypocalcemia (dSCH): primiparous: [Ca] > 8.6 mg/dL at 1 DIM and ≤8.6 mg/dL at 2 DIM, multiparous: [Ca] > 7.08 mg/dL at 1 DIM and ≤8.8 mg/dL at 4 DIM. Serum Ca concentrations did not influence milk yield. However, significant differences were observed in serum malondialdehyde (MDA) and total antioxidant capacity (TAC), as well as in milk somatic cell scores (SCS), between NC cows and other groups. At 1 DIM, cows with dSCH showed significantly elevated serum globulin, total protein, and albumin-to-globulin ratio(A/GR), with lower albumin concentrations compared with NC cows. Cows in dSCH and tSCH also had a lower incidence of metritis and lower total cholesterol concentrations on d 1, 4, and 10 postpartum. Milk fat content at 100, 200, and 305 DIM differed significantly across different types of subclinical hypocalcemia compared with NC. Our results demonstrate that dairy cattle with dSCH have lower serum albumin and cholesterol concentrations, higher globulin concentration, and a disrupted albumin to globulin ratio. Changes in production indicators, such as reduced milk fat, increased SCS, and lower conception rate indicate an active immune response and hidden inflammation. These findings confirm the dysregulation of the Calci-Inflammatory Axis in dSCH cases, highlighting the need to assess hypocalcemia as both a metabolic imbalance and a key indicator of immune and inflammatory health.

The objective of this study was to compare growth and future milk production of Holstein calves fed either an intensified liquid feeding program (INT; n = 32) or a conventional early weaning program (CON; n = 33). At 3 d of age, female Holstein calves in individual hutches were assigned to CON (milk replacer [22% CP, 20% fat] plus starter [18% CP, as fed]) or INT (milk replacer [28% CP, 20% fat] plus starter [22% CP, as fed]). In yr 1, 12 calves on CON and 11 calves on INT were used, whereas in yr 2, there were 21 calves on each treatment. For CON, calves were fed a constant amount of milk replacer (1.25% of birth weight as powder) through wk 4, were fed one-half of that amount during wk 5, and were weaned at the end of wk 5. For INT, calves were fed milk replacer at 2% of BW during wk 1 and 2.5% of BW during wk 2 to 5 (adjusted weekly in yr 1, held constant in yr 2). During wk 6, calves were fed half the amount offered during wk 5 and were weaned at the end of wk 6. After wk 8, calves were housed together by treatment in superhutches through wk 12. Total milk replacer consumed was greater for INT compared with CON, but CON consumed greater amounts of calf starter over the 8 wk trial. Body weight, withers height, body length, and heart girth were increased during the milk-fed period and through wk 8. Average daily gain was greater for INT at wk 4, at weaning, and at wk 8. Gain to feed ratio was greater for INT than CON. By wk 12, there was no difference in BW between groups. Calving BW and age at first calving were not different between groups. Primiparous cows that were fed INT as calves produced 1,048 kg more milk than CON herdmates. Production of milk protein also was greater for INT, but milk fat did not differ between groups. In conclusion, feeding more milk replacer to calves resulted in greater early growth, but that was not maintained through 12 wk. Regardless, primiparous cows fed INT as calves produced more milk and milk protein than those fed CON.

Liver function is critical for high-producing dairy cows to achieve high milk production and good fertility, as well as to avoid periparturient health problems. Key processes include gluconeogenesis, fatty acid metabolism, protein synthesis, amino acid metabolism and urea formation, bile acid synthesis, detoxification, endocrine functions, and immune functions. Various tests have been used to assess liver function. Fatty liver develops when fatty acid uptake exceeds the liver's capacity to oxidize fatty acids and export triacylglycerols and may negatively affect hepatic function. Metabolomics, transcriptomics, and proteomics are opening new insights into hepatic adaptations in normal and abnormal situations, such as the roles of acylcarnitines, lysophospholipids, and sphingolipids. Nutritional strategies such as controlled energy dry cow diets and supplemental rumen-protected methionine and choline help maintain liver function during the periparturient period. Nutritional manipulations that impact liver function help to promote health and productivity of high-producing dairy cows.

The main challenge to producing a nutritionally improved milk fat composition is to increase monounsaturated fatty acids (MUFA) and decrease saturated fatty acids (SFA) without detriment to dairy product characteristics. Our aim was to determine the optimal amount of intestinally available oleic acid (via abomasal infusion) to produce higher-MUFA milk fat with satisfactory functional characteristics for ice cream. One control and four increasing doses of free fatty acids (FA) from high oleic sunflower oil (HOSFA) were infused into the abomasa of four lactating dairy cows in a changeover design with periods of 7 d. Treatments were (1) control (no FA infused), (2) HOSFA (250 g/d), (3) HOSFA (500 g/d), (4) HOSFA (750 g/d), and (5) HOSFA (1000 g/d). All treatments included meat solubles and Tween 80 as emulsifiers. Ice cream mixes were prepared with butter oil from all treatments. Samples prepared from control and 500 g/d HOSFA infusion were evaluated by a judging panel in a triangle test. Statistical analysis of results showed linear changes in most of the variables analysed as HOSFA infusion increased. For ice cream under freezing temperatures, the 500 g/d level was optimal. Sensory evaluation analysis indicated no statistical difference between ice creams prepared from the control and 500 g/d HOSFA infusion. Changes in 23 triacylglycerol fractions were statistically correlated to functional properties at 10 min of freezing. The decrease in fractions with SFA (butyrin-caprylin-palmitin, butyrin-laurin-olein, butyrin-myristin-palmitin, butyrin-palmitin-palmitin, caproin-myristin-palmitin, butyrin-palmitin-stearin, caproin-palmitin-palmitin) and the increase in dioleyl triglycerides (with butyric, lauric, myristic and palmitic acids) and triolein were some of the most highly correlated with ice cream functional properties as the result of increasing HOSFA infusion. We were able to produce an ice cream with desirable physical and organoleptic qualities, yet containing twice as much oleic acid and two-thirds as much palmitate as a control ice cream.

Ruminants rely on hepatic gluconeogenesis to support whole-body glucose metabolism and to supply glucose for lactose synthesis. Understanding the effect of plane of nutrition before parturition on the capacity for hepatic gluconeogenesis in dairy cows may provide a basis for improved cow health and productivity in the subsequent lactation. Our objectives were to determine the effects of far-off (FO) dry period diet, close-up (CU) period diet, and their interaction on adaptations in metabolism of gluconeogenic substrates (Ala and propionate) in liver slices. Multiparous Holstein cows (n = 71) were fed different amounts of nutrients during the FO and CU dry periods in a 3 (FO diet) × 2 (CU diet) factorial arrangement. During the FO period (d -60 to -25 before calving) cows received a control diet fed for ad libitum intake to meet NRC recommendations (100NRC), a moderate energy diet fed ad libitum to exceed NRC recommendation for NEL by at least 50% (150NRC), or the moderate energy diet fed at restricted intake to meet 80% of NEL requirements (80NRC). During the CU period (d -24 until parturition), cows were fed a diet either for ad libitum intake (CUA) to meet or exceed NRC recommendations or in restricted (CUR) amounts to provide 80% of calculated NEL requirements. All cows received the same lactation diet postpartum. Liver slices from biopsies at d -30, -14, 1, 14, and 28 relative to parturition were used to determine in vitro conversion of [1-¹⁴C] Ala and [1-¹⁴C] propionate to glucose and CO₂. Gluconeogenic rates from propionate were 71%, 37%, and 73% greater than from Ala on d 1 for cows fed 100NRC, 150NRC, and 80NRC, respectively. Gluconeogenesis from propionate was significantly greater on d -14 and d 28 for cows fed 80NRC compared with 100NRC and 150NRC. Oxidation of propionate to CO₂ increased from d -14 to d 1 postpartum for all far-off treatments. On d -14, oxidation of propionate to CO₂ tended to be lower for 100NRC versus 150NRC and 80NRC. Gluconeogenesis from Ala on d -30 tended to be less for 150NRC compared with 80NRC. Gluconeogenesis from Ala tended to be greater for CUR on d 14. Oxidation of Ala to CO₂ was not significantly different among treatments but tended to be higher on d 1 postpartum for 100NRC. Close-up diets had minimal effects on gluconeogenesis and substrate oxidation. Cows fed restricted amounts of energy in the FO dry period had greater hepatic gluconeogenic capacity both prepartum and postpartum compared with those fed excess amounts of energy relative to requirements. Controlling energy intake during the far-off dry period can alter hepatic capacity for gluconeogenesis from propionate and Ala, which may confer an advantage to the cow by adapting metabolic processes before parturition and resulting in improved health and productivity.

The use of yeast products, phytogenics, and direct-fed microbials (DFM) have been shown to improve health and growth performance of dairy calves. More recently, combining nutrients and additives to optimize calf performance has become a growing interest area. The purpose of this study was to determine if feed additives in milk replacer (MR) and starter could improve health and growth of Holstein calves through 13 wk of age. Ninety male Holstein calves <4 d of age were assigned to 1 of 3 treatments. Calves were individually housed in outdoor hutches through d 56, then moved to group pens through d 92. Treatments were a control MR and pelleted starters with no additives (CON); a MR with phytogenics and yeast extract plus a starter with a blend of phytogenics and yeast products (CTP); and the same CTP MR with a starter containing an experimental blend of phytogenics, yeast products, and DFM (CEP). Diets were formulated as follows: MR contained 22% CP and 20% fat and starters contained at least 16% CP and 4% fat (as-fed basis). Average initial BW were 42.1 (±5.9) kg for CON, 42.9 (±4.9) kg for CTP, and 43.3 (±5.5) kg for CEP. Calves were fed MR at a rate of 600 g/d (as fed), reconstituted to 13% solids. This amount was fed from d 0 to 42 when the single step-down weaning process started by discontinuing the evening MR feeding. After d 49, MR was completely discontinued but calves stayed in individual hutches through d 56 and then were moved to group housing. During the group-housed portion of the experiment, calves were provided with ad libitum pelleted starters and water. Health scores were collected twice daily from d 1 to 56, and once daily from d 57 to 70. Body weight and frame measurements were collected weekly. Average ME intake was consistently greater for CTP throughout the trial, and starter ME intake was greater compared with CON for wk 4 to 13. Final BW was greater for CTP and CEP for wk 1 to 13 relative to CON. Frame growth was improved for CTP and CEP during wk 1 to 8 in comparison to CON. Feed efficiency tended to be greater for CTP and CEP compared with CON during wk 9 to 13. There was a tendency for lower incidence of scours for calves fed CTP, and overall health and need for medication were improved for calves fed both CTP and CEP compared with CON. Results of this study indicate improvements in pre- and postweaning health and growth of calves fed blends of yeast products, phytogenics, and DFM in MR and pelleted starters.

Feeding plasma protein has been shown to have health benefits and help ameliorate stress in preweaning calves, aiding their ability to handle the challenges of weaning and initial social interactions. We hypothesized that feeding plasma proteins would improve health and growth in newly weaned calves under stress from postweaning commingling. The objectives of this study were to assess the health, growth, and stress responses of calves fed bovine plasma proteins in their grower feed, specifically evaluating whether feeding plasma proteins could reduce plasma cortisol concentrations during the transition to group housing. During experiment 1, 21 castrated male Holstein calves were housed outdoors in groups of 3 from 10 to 14 wk of age. Experiment 2 included 40 castrated male and female Holstein-Angus cross calves housed outdoors in groups of 6 or 7 from 9 to 13 wk of age. Both experiments were randomized, complete block designs. Data from experiments 1 and 2 were pooled. Treatments were a control grower diet with no bovine plasma protein (CON; 20% CP, 2.4% fat) and a grower diet including spray-dried bovine plasma protein (SDP; 20% CP, 2.9% fat). Experiment 1 had 3 CON pens and 4 SDP pens, and experiment 2 had 3 CON pens and 3 SDP pens. Pen was the experimental unit. Both experiments provided ad libitum water and grower feed with a 2.5% inclusion of chopped wheat straw. Data collection was the same during both experiments. Feed intake and health scores, including assessment of fecal, ocular, nasal, ear, and respiratory events, were recorded daily. Body weight was recorded weekly, and skeletal growth measurements were recorded on d 0 (Exp 1) or d -1 (Exp 2), and d 28. Blood samples were collected via jugular venipuncture on d 0 (Exp 1) or -1 (Exp 2), d 3, and d 7 (Exp 1) or d 6 (Exp 2); plasma was stored at -20°C for later analysis. Average daily gain, feed intake, and plasma cortisol data were analyzed using the MIXED and UNIVARIATE procedures in SAS, and health data were analyzed using the FREQ and GLIMMIX procedures. No differences were detected for BW, frame growth, or ADG, and no differences were observed between treatments for health scores. Grower feed intake was not different between treatments. No differences in cortisol concentrations (1.04 ng/mL for CON and 1.06 ng/mL for SDP) were observed between CON and SDP calves. Bovine plasma proteins did not enhance growth, health, or feed intake in this study. Weaning-related stressors did not raise plasma cortisol concentrations, and plasma protein supplementation had no effect on growth or cortisol concentrations.

Summary: The purpose of this analysis was to establish the effects of birth season on the performance of first-lactation Holstein cows. Further analysis was conducted to determine the impact of calving season. This study analyzed data from 2009 to 2022 and included 524 first-parity Holstein cows from the University of Illinois Dairy Research Unit. An association between birth and calving seasons in relation to first-lactation cow performance was observed. A pattern of reduced milk production and reproductive performance was noted for summer-born and summer-calving cows. These data indicate opportunities for improvement in feeding and management strategies for cows born or calving during the warmer summer season.

Optimizing protein nutrition is pivotal for enhancing growth, metabolic efficiency, and long-term productivity of dairy calves. This review summarizes current research on precision protein feeding based on the NASEM (2021) model, which aligns MP and ME with calf developmental stages to optimize nutrient utilization. In the preweaning phase, the CP requirement of Holstein calves (<125 kg BW) increases with increasing ADG, with a 50-kg calf requiring 102 g of CP (18.2% DMI) for 0.2 kg/d ADG and 315 g of CP (25.5% DMI) for 1.0 kg/d ADG, with ME intake increasing from 2.56 to 5.66 Mcal/d. The review underscores the importance of adjusting the CP-to-ME ratio; adequate supply of limiting AA such as Lys, Met, and Thr; and a balanced ratio of RDP and RUP to optimize growth and metabolism. Amino acids are essential for muscle development, immune response, and enzyme function. Protein intake in the preweaning phase improves growth performance, weight gain, and feed efficiency, although excess protein in the diet can reduce overall growth efficiency. The balance between RDP and RUP is critical for microbial protein synthesis and nitrogen retention, with RDP becoming the dominant protein source after weaning due to increased reliance on microbial protein. Furthermore, macronutrient-specific adjustments in milk replacers, such as the addition of protein, fat, or lactose, lead to different metabolic responses, with protein primarily supporting lean tissue building, whereas fat and lactose promote energy storage. These findings emphasize the need for precise nutritional strategies that consider protein quality and AA availability to ensure optimal growth and metabolic efficiency. Furthermore, protein levels in calf starter diets, ideally between 20% and 23% CP (DM basis), lead to optimal growth, especially when combined with moderate to high milk feeding, although higher protein levels are not always growth promoting, highlighting the need for precise nutritional adjustments according to the developmental needs of the calf. For growing heifers, protein nutrition after weaning continues to be a critical factor in optimizing growth, efficiency, and later lactation performance. Stage-specific adjustments to the balance between RDP and RUP are important to support microbial protein synthesis and nitrogen retention, with RDP becoming the dominant protein source as heifers mature and transition to a more energy-driven fat deposition phase. These findings are critical for refining protein and energy utilization strategies, optimizing calf development, and supporting long-term lactation performance. In summary, this review provides insights into the optimal protein feeding strategies to improve calf growth and metabolic efficiency in the pre- and postweaning phases.