Regulation of Feed Intake in Transition Cows Barry Bradford Associate Professor Kansas State University 135 Call Hall, Manhattan, KS

Typical Transition Cow Goals Avoid transition disorders Promote a steady rise in feed intake and milk production to meet peak lactation goals Set the stage for reproductive success Key to all of these: Minimize time and degree of negative energy balance

Promoting energy intake Energy intake = dry matter intake Xenergy density Management Carbohydrate profile Bioactive nutrients Nutrient profile

Liver is “hard-wired” to brain feeding centers via vagus nerve Great variation in pattern of oxidation of fuels over the short-term Feed intake is affected by pattern of oxidation Goal: maximize the amount of glucose produced per unit of ATP generated in the liver over time Hepatic Oxidation Theory (HOT)

What are “hot” and “cold” diets? Hot = highly fermentable – Highly digestible forage sources – Relatively high concentrate levels – Some substitution of forage with nonforage fiber sources (byproducts) Cold = less fermentable – Higher forage concentrations – Some poorly digestible forage (i.e. straw) – Resistant starch and/or nonforage fiber replaces some processed starch

HOT Diet Maximal milk yield Satiety Peak lactation cow

COLD Diet Milk yield constrained by nutrient supply Satiety Peak lactation cow

What about the transition cow?

Fat mobilization Triglycerides (TG) Oxidized or Stored as TG Fatty Acids (NEFA) Oxidized Milk Fat TG Liver Muscle Adipocytes Mammary

lipolysis, lipogenesis Depressed feed intake during the transition period hepatic oxidation feed intake plasma glucose plasma insulin NEFA

Can limiting NEFA release preventing DMI depression? Fed 24 g/d rumen-protected niacin Close-up ration: – 35% NFC, 42% NDF, 1.55 Mcal NEL / kg DM Fresh cow ration: – 40% NFC, 32% NDF, 1.69 Mcal NEL / kg DM Treatments from 21 days before calving to 21 DIM Morey et al., 2011

Encapsulated niacin decreased plasma NEFA Day relative to calving Morey et al., 2011

Niacin did not increase DMI Day relative to calving Morey et al., 2011

Niacin has NEFA-independent effects Titgemeyer et al., 2011

lipolysis, lipogenesis Depressed feed intake during the transition period hepatic oxidation feed intake plasma glucose plasma insulin NEFA + Propionate - Propionate

Propionate has dual effects in early lactation Experimental infusion of propionate for 72 hours in early lactation decreased feed intake by 10% compared to acetate infusion This response was the most dramatic in cows with high blood NEFA concentrations Stocks and Allen, 2010, 2011

How much starch in early lactation? Diets were based on corn silage (35%) and alfalfa silage (11.5%) and included 4% wheat straw Corn meal, soy hulls, and wheat midds were varied Nelson et al., 2011

High starch diet limited DMI Trt: P = 0.06 Time: P < Trt x Time: P = 0.09 LL > HH: P ≤ 0.10 Nelson et al., 2011 Courtesy of H. M. Dann n = 78 (total)

…and milk yield Nelson et al., 2011 Courtesy of H. M. Dann Trt: P = 0.04 Time: P < Trt x Time: P = 0.75 MH > HH: P ≤ 0.05 n = 78 (total)

Moderate starch delayed NEFA normalization Nelson et al., 2011 Courtesy of H. M. Dann n = 78 (total)

What about sugar? Sucrose was used to replace cracked corn grain at 4.7% of diet dry matter Diets were approximately 34% NDF, 34% NFC – 20.5 vs. 18.5% starch – 4.5 vs. 8.7% water-soluble sugars Fed for first 28 days in milk Penner and Oba, 2009

Dietary sucrose increased DMI, ECM P = 0.04 P = 0.09 Penner and Oba, 2009 Over the first 28 days in milk n = 52 (total)

Dietary sucrose in transition diets Sucrose did not alter energy balance Sucrose decreased plasma glucose and increased NEFA and BHBA concentrations Increased ruminal pH (6.06 vs. 6.21, P = 0.08) Increased total-tract OM digestibility, not NDF Increased ruminal NDF digestibility and passage? Penner and Oba, 2009

Fat in peak lactation? Cows were fed a common diet for first 21 DIM, then randomly assigned to 1 of 4 diets: 60:40 forage:concentrate – 2.9% fatty acids – 5.0% fatty acids (prilled hydrogenated fatty acids) 40:60 forage:concentrate – 3.4% fatty acids – 5.5% fatty acids (prilled hydrogenated fatty acids) Weiss and Pinos-Rodriguez, 2009

Fat in peak lactation? Weiss and Pinos-Rodriguez, 2009 n = 72 (total)

Fat in peak lactation? Weiss and Pinos-Rodriguez, 2009 n = 72 (total)

Fat in peak lactation? Weiss and Pinos-Rodriguez, 2009 n = 72 (total)

Fat in peak lactation? Weiss and Pinos-Rodriguez, 2009 n = 72 (total)

Transition diet recommendations Goals: Decrease NEFA, maintain rumen fill Feed fiber with long ruminal retention time Target moderate starch fermentability to supply adequate propionate without rapid production in a meal Consider using a sugar source (4-5% of DM)

When to change to the peak diet? Ideally, change to peak-lactation diet when plasma NEFA and ketones decrease and intake is steadily increasing Practically, cows with steadily rising feed intake and milk yield may be ready to shift diets as early as 7 days in milk, or as late as 21 days in milk

Peak lactation Dry matter intake is limited by gut fill in most cows Additional energy in the form of starch or fat should not depress DMI (within reason) Additional energy can increase BOTH milk production and BCS

Conclusions Attempts to prevent negative energy balance in early lactation haven’t worked! More energy in = more milk, in most cases There is hope for improved feed intake, which generally improves transition performance

Thank you!