Kevin J. Harvatine

The objectives of this study were to review the literature and use meta-analytical methods to determine the effects of supplementing hydroxychloride (HTM) compared with sulfate (STM) sources of Cu, Mn, and Zn on production performance of dairy cows. The literature was systematically reviewed, searching for randomized experiments that replaced STM with HTM in diets fed to lactating dairy cows. A total of 7 experiments met the inclusion criteria, of which 5 were Latin square designs and 2 were continuous designs, representing 283 unique cows and 518 experimental units. The individual cow data were obtained from investigators and data were computed as means per experimental unit. Responses of interest included intake of DM and trace minerals, yields of milk and milk components, feed efficiency, body weight, body condition score, and mineral concentrations in tissues. Predictors included treatment, if STM or HTM, the experimental design, if Latin square or continuous, and the experiment itself. Dietary ingredients were entered into the NASEM (2021) software to estimate the NEL content of each diet to calculate energy balance. Data were analyzed using mixed-effects models including the fixed effects of treatment, experimental design, and the interaction treatment and experimental design, and the random effect of experiment nested within experimental design. Treatment did not affect the daily intakes of DM (STM = 24.5 vs. HTM = 24.9 ± 0.9 kg/d), Cu (STM = 494 vs. HTM = 500 ± 27 mg/d) and Zn (STM = 2,235 vs. HTM = 2,272 ± 213 mg/d); however, cows fed HTM consumed 118 ± 22 mg/d more Mn than those fed STM (STM = 1,754 vs. HTM = 1,872 ± 95 mg/d). Yields of milk, fat, and true protein tended to increase 1.0 ± 0.6, 0.044 ± 0.023, and 0.031 ± 0.016 kg/d, respectively, in cows fed HTM compared with STM, whereas yield of ECM and the amount of net energy secreted as milk increased 1.1 ± 0.5 kg/d and 0.76 ± 0.39 Mcal/d, respectively, in cows fed HTM compared with STM. Source of trace mineral did not affect feed efficiency, body weight, body condition score, or net energy balance of cows. Source of trace minerals did not affect the concentrations of Cu, Mn, or Zn in serum of cows. There was no evidence of an interaction between source of trace mineral and design of experiment for any of the responses evaluated. Furthermore, there were no indication of heterogeneity or publication bias. These results suggest that supplementing HTM compared with STM as sources of Cu, Mn, and Zn in diets of lactating dairy cows benefits production performance.

A large proportion of human food is lost during storage, processing, and distribution and has a large impact on the efficiency and environmental footprint of the food system. Grocery stores and other distributors provide a convenient point for industrial collection and recovery of unsalable food items such as fruits, vegetables, bakery items, and other products that can be diverted into animal feed, reducing disposal costs and methane production associated with landfilling and composting while upcycling nutrients. Twenty primiparous and 28 multiparous Holstein cows were blocked by parity and milk production and randomly assigned to either control or a TMR containing recovered grocery food at 7.5% or 15% of diet DM for 40 d in an incomplete randomized block design. Recovered grocery food was collected from several grocery stores and was delivered to the farm approximately every 4 d and was stored on a concrete pad. The average pH of the product before feeding was 3.5 and was never above 4.5. Recovered grocery food averaged 33.2% NDF, 14.3% starch, 10.9% water soluble sugars, 15.5% CP, and 17.9% total fatty acids. There was a treatment by parity interaction for DMI. The recovered grocery food decreased DMI on 7 d in both parity groups but intake then progressively increased. Multiparous cows were not different from the controls after d 21 and the grocery food increased intake in primiparous cows after 21 d. There was no main effect of treatment or interactions of treatment and time or treatment and parity on milk yield or milk fat percent or yield, but there was a quadratic effect of treatment on milk yield on d 21. There was a treatment by time interaction on milk protein concentration with a linear decrease from d 21 to 40 (3.15 vs. 3.01%). However, there was no effect of treatment on milk protein yield. Milk urea nitrogen was linearly increased with increasing grocery product. There was no effect on total-tract dry matter digestibility, but NDF and fatty acid digestibility was linearly increased by the recovered grocery food. The grocery product maintained a very low pH and a relatively stable nutrient composition during the experiment. Feeding up to 15% of the ration as recovered unsaleable grocery fruit, vegetables, and bakery products in place of molasses and ground corn maintained milk and milk component production and increased fiber digestibility, providing evidence that this byproduct can be effectively used in rations of lactating dairy cattle.

Oleic acid has a lower risk for biohydrogenation-induced milk fat depression (MFD) than linoleic acid and can act as an emulsifier to aid fatty acid (FA) digestion in the small intestine. Our objective was to evaluate the effect of high oleic expeller soybean meal compared with conventional expeller soybean meal when feeding diets that differed in risk for MFD. We hypothesized that the high oleic expeller soybean meal would increase milk fat by reducing the risk for MFD and increasing FA digestibility. Eighteen multiparous Holstein cows were used in a crossover design with 24 d periods. Each period consisted of 2 dietary phases that differed in risk for diet-induced MFD. During the first 14 d, a diet with a lower risk for MFD (32% NDF, 22.2% starch, and no added oil) was fed and during the final 10 d the risk for MFD was moderately increased by decreasing fiber and increasing starch and unsaturated FA (28.5% NDF, 27.7% starch, and 0.5% corn oil). The treatments were conventional expeller soybean meal and expeller meal from high oleic soybeans fed at 7.5% of diet DM. Milk production was measured in both phases, while digestibility was measured only during the moderate-risk phase. Data was analyzed in SAS using PROC MIXED using a model with cow and period as random effects and treatment, phase, and their interaction as fixed effects. There were no effects of treatment on milk yield or milk fat and protein yield or composition. Overall, milk fat concentration decreased with the higher MFD risk diet, while milk protein concentration increased. Cows fed high oleic expeller soybean meal increased DMI. Feeding high oleic expeller soybean meal also tended to decrease total-tract digestibility of DM and NDF. Overall, feeding cows expeller meal from high oleic soybeans resulted in similar milk production to conventional soybeans and did not improve milk fat yield or total-tract FA digestibility, likely because of the lower fat level of expeller soybean meal.

Dairy producers invest in fatty acid (FA) supplements to increase energy intake and maximize milk fat yield, but the effect of dietary fat level on mammary FA uptake and metabolism are not well described. Our objective was to characterize mammary arteriovenous (AV) difference and extraction percentage of total plasma FA, triglycerides (TG), and nonesterified FA (NEFA) at 2 levels of dietary fat. The hypothesis was that mammary AV difference of palmitic acid (16:0), stearic acid (18:0), TG, and NEFA would be greater in cows fed a higher fat diet compared with a lower fat diet due to increased arterial concentration and therefore substrate availability of these FA. The secondary hypothesis was that mammary extraction percentage of FA would increase as arterial concentration of FA increased, suggesting a concentration-dependent mechanism of uptake. Nine multiparous Holstein cows were arranged in a crossover design with 14 d periods. Treatments were a lower fat diet (LF; 2.7% FA) or a higher fat diet that contained roasted soybeans, whole cottonseed, and a prilled FA supplement (HF; 4.9% FA). Data were analyzed in a mixed model that included the random effect of cow and period and fixed effect of treatment. For plasma analysis, the fixed effect of time and interaction of treatment and time were added to the model. There was no effect of treatment on milk or milk protein yield. Feeding the HF diet increased milk fat percent 0.26 units and milk fat yield by 88 g/d, with an increase in the yield of > 16 C preformed and 16 C mixed source FA. The HF diet increased the proportion of 16:0, 18:0, and linoleic acid (18:2 n-6) in both arterial and venous plasma FA and decreased the proportion of oleic (18:1 c9) and α-linolenic (18:3 n-3) acid. It also increased total arterial FA concentration by 21%. Approximately half of the increase in arterial FA was due to 18:2 n-6 (+ 232 mg/L), while smaller increases were also observed for 16:0, 18:0, 18:1 c9, and 18:3 n-3. There was a treatment by time interaction for the AV difference of total FA and 18:1 c9 and a tendency for an interaction for 18:0 and 18:2 n-6, where there was a greater AV difference between treatments at 1600 h compared with other time points. The HF diet also increased the AV difference of 16:0, but there was no interaction of treatment and time. There was no treatment or treatment by time interactions for AV difference of TG and NEFA. There was an interaction of treatment and milking time for milk fat percent that aligned with total plasma FA AV data, where the difference between HF and LF was greater at the evening milking compared with the morning. In conclusion, increasing dietary fat increased milk fat yield through an increase in total plasma FA concentration and an increase in AV difference of specific FA with variation in the response across the day.

Fatty acid (FA) supplements are commonly fed to increase the energy content of lactating dairy cow diets and improve milk and milk fat yield and energy balance. However, increasing dietary fat commonly decreases FA digestibility. Our objective was to investigate the effects of magnesium salts of fatty acids or exogenous emulsifiers in a FA prill on milk yield and composition and FA digestibility. Fifteen multiparous Holstein cows were randomly assigned to treatment sequence in a 5 × 5 Latin square design with 14-d periods. The treatments were (1) conventional FA prill (CON; 51.2% 16:0, 31.7% 18:0, 7.11% cis-9 18:1) or FA prills that contained (2) magnesium salts of FA (2.2% Mg; MAG), (3) lysophospholipids (LYSO), (4) 18:0 monoglyceride (MONO), or (5) polysorbate 60 (POLY). All cows received the same basal diet and the FA prills were fed at 2% of diet DM. Treatments had no effect on DMI, milk yield, or milk fat and protein concentration or yield. The addition of lysophospholipids increased the concentrations of preformed FA in milk compared with CON, primarily driven by an increase in cis-9 18:1. The addition of polysorbate increased 16 C FA digestibility compared with MAG and MONO. There was no effect of treatment on total or 18 C FA digestibility. Both MONO and POLY decreased NDF digestibility compared with CON and MAG, but there was no effect on DM digestibility. Overall, addition of emulsifiers resulted in changes in 16 C FA digestibility and preformed FA, indicating modification of FA absorption, but these did not translate to changes in milk production. Future work should explore rumen protection and possibly other types of these emulsifiers.

The objectives of this experiment were to assess the effect of prepartum acetylsalicylic acid administration to Holstein dairy cows on 1) colostrum quantity, composition, and quality; and 2) immune, metabolic, and inflammatory status, and growth in their Holstein dairy heifer calves. Prepartum cows (n=205) from a commercial dairy farm located in central Pennsylvania were enrolled in the study. At 14±3 d prior to expected calving date, cows were blocked by parity (Nulliparous, n=58; parous, n=147) and randomly allocated into one of two treatment groups: 1) ASA (n=102): Cows received one oral administration with 4 boluses of acetylsalicylic acid (480 grain/bolus; equivalent to 125 grams/cow); or 2) PLC (n=103): Cows received one oral administration with 4 gelatine boluses filled with water. Only alive singleton heifer calves were enrolled in the study (ASA-CLF, n= 47; PLC-CLF, n=46). Colostrum samples (ASA=51; PLC=54) were collected during the first milking. Blood samples and body weight were collected within 3 days after birth and then weekly until week 4 and week 8, respectively. The data were analysed using UNIVARIATE and MIXED procedures of SAS as a randomized complete block design. An interaction between treatment and lactation was observed in ≥ 3rd lactation cows, where ASA-treated animals had lower IgG concentrations than PLC-treated cows. Calves born to ASA-treated cows had higher serum IgG, serum total protein concentration, and non-esterified fatty acids, within three days after birth, compared with calves from placebo-treated cows. These findings suggest that prepartum ASA treatment may be negatively associated with colostrum IgG concentration only in ≥ 3rd lactation cows, and may yield positive effects on calf immunity during the first week of life.

Milk fat is a major source of dairy farm income, and methods to increase milk fat yield are of strong interest to producers and nutritionists. Sodium acetate supplementation increases milk fat in lactating cows, but dietary factors that affect ruminal acetate synthesis may modify the response to acetate supplementation. Our objective was to test the interaction between acetate supplementation and dietary UFA concentration. The hypothesis was that acetate would increase milk fat yield more when supplemented in diets containing high levels of UFA compared with low levels of UFA. Twelve multiparous Holstein cows were randomly assigned to treatment sequence in a replicated 4 × 4 Latin square design with 21-d periods and 2 × 2 factorial arrangement of treatments testing the effect of acetate (AC; 600 g/d of acetate as sodium acetate) and increasing UFA by the addition of soybean oil to the diet (1.5% of diet DM). There was no effect of UFA, AC, or their interaction on DMI or total-tract DM or NDF digestibility. Increasing UFA increased total-tract fatty acid (FA) digestibility by 8 percentage units, but there was no effect of AC. There was no interaction between UFA and AC for plasma concentration of nonesterified FA (NEFA), BHB, insulin, or individual 16 C and 18 C FA of interest, although there was a tendency for an interaction for plasma glucose. Overall, acetate tended to decrease plasma glucose and increased plasma BHB. Increasing UFA also increased plasma BHB and NEFA as well as plasma 16:0, 18:0, cis-9 18:1, 18:2 n-6, 18:3 n-3, and trans-18:1 FA. There was no interaction of AC and UFA for milk yield, milk fat concentration, or milk fat yield. Both AC and UFA increased milk yield. Acetate increased milk fat yield 140 g/d and milk fat percent 0.16 units, mainly due to an increase in mixed-source 16 C FA and a smaller increase in de novo and preformed FA. Increasing UFA had no effect on milk fat concentration or yield. Transfer efficiency of both consumed and absorbed 18 C FA were decreased with UFA, but AC increased transfer efficiency of consumed 18 C FA. The lack of interactions between UFA and AC throughout the experiment may have been due to the failure of UFA to decrease fiber digestibility. However, increased FA availability with UFA did decrease milk de novo FA yield and thus mammary total acetate needed for milk fat synthesis. Additionally, the lack of interaction between UFA and AC for milk fat production suggests that both the high and low UFA diets may have been limited in acetate production or that the mechanism of increased de novo FA synthesis when providing additional acetate as substrate is independent of the decrease in de novo synthesis that commonly occurs when increasing dietary FA.