Florida researchers began a generational study in 2007 that is still years in the making. It all began with the investigation of the impact of heat stress on dry cows to measure changes that might occur to the calf incubating inside the hot dam, like a crock pot.

In addition to seeing negative production impacts on mama, the researchers began to measure numerous changes in the damaged calf coming out of the heat stressed dry cow. This month’s edition, we’ll be interviewing Dr. Jimena Laporta, of the University of Wisconsin, to better understand the physiological changes of the calf that results in lost production for her entire life. She and her team measured changes in mammary and adrenal gland development.

Several separate papers have been peer reviewed over the 17 years of research. Many are linked at the bottom of the show notes for additional reference.

Listen in to understand how heat stressed dry cows can destroy your favorite cow families’ production records.

This month features two released paper titled: (1) Carry-over effects of maternal late-gestation heat stress on granddaughter’s growth and mammary gland development (ck out histology – Fig 1&2) (2) Programming effects of intrauterine hyperthermia on adrenal gland development

Topics of discussion

1:58 Introduction of Dr. Jimena Laporta 4:17 Describe the experimental design 6:19 Description of the generations impacted through in utero heat stress 7:29 The biological link between the grand dam and the grand daughter (F2) 9:16 Eight years of research to collect multigenerational data 10:39 F1 management in WI beginning at 8 weeks 12:00 F1 mammary implications following heat stress while developing in utero 13:32 F2 calves – changes as a result of dam’s exposure to heat stress while developing in utero 15:01 Early mammary growth 15:32 What is causing these differences in F2 17:35 Lumen space and estrogen receptors 19:06 Summary of 3 generations of damage 20:34 Should I build a lactating barn or dry cow barn? 22:39 The Adrenal Gland 27:38 Adrenal effect on inflammation 28:56 What do you want Boots on the ground dairyman to know

Background Information: Temperature Humidity Index (THI) 2020 Dairy Science Digest Podcast interview 2020: Late-gestation heat stress impairs daughter and granddaughter lifetime performance (economic impact) 2016: In utero heat stress decreases calf survival and performance through the first lactation

#2xAg2030; #journalofdairyscience; #openaccess; #MODAIRY; #heatstress; #fetalprogramming; #F1; #milk; #adrenal; #mammarydevelopment; #mammary; #dairysciencedigest; #ReaganBluel;

Choline, a pseudovitamin, is required by all mammals including the dairy cow for many essential functions. Research in supplementing rumen protected choline really took off about twenty years ago, however continues today to best understand how this feed through additive can positively influence profitability. Dr. Usman Arshad joins the conversation for this episode to highlight his comprehensive summary of all the peer reviewed, published research completed on Choline. Listen in to best understand the assumed mode of action choline uses to help provide an improved efficiency in milk production for the majority of the lactation, even when only fed during the 42-day transition period.

The findings we discuss are published in the recently released paper titled: Exploring choline's important roles as a nutrient for transition dairy cows

Topics of discussion

1:19 Introduction of Dr. Usman Arshad 2:17 What is Choline? 3:45 Phospholipid production – choline’s role 6:15 How does choline impacts the transition Cow 7:46 Fatty acid impact on the Liver 8:39 Major factor choline plays on fatty acid transport 13:16 Twenty year average Milk Response when feeding choline for 42 days (-21 to 21 dim) 15:47 Milk Response when feeding choline – more current average from 2020-2024 17:18 Mode of action, intestinal lining? 20:02 Additional possible modes of action 21:47 Choline as a treatment for fatty liver 23:24 Choline results in elevated milk yield, regardless of body condition score 26:16 Inflammation through in early lactation 27:29 Energy cost of bacterial infection 30:30 What’s the one take home message for boots on the ground dairymen 31:35 Return on investment calculations

Featured article: Exploring choline's important roles as a nutrient for transition dairy cows

#2xAg2030; #journalofdairyscience; #openaccess; #MODAIRY; #Choline; #transition; #transitiondairy; #vitamin; #fattyacid; #negativeenergybalance; #TMR; #dairysciencedigest; #ReaganBluel;

DSD 5.3 | Slight modifications of CIDR Sync - help or hinder?

In this time of heifer inventory shortage – getting heifers pregnant (in a timely fashion) is even more important than ever.

Contract heifer growers in California sought the help of Dr. Fabio Lima and his team at UC Davis to best understand the use of a 6-day CIDR sync with variable rates of GnRH could increase pregnancies when bred to sexed semen.

The findings we discuss are published in the recently released Journal of Dairy Science article titled: Effect of 200 μg of gonadorelin hydrochloride at the first GnRH of a CIDR Synch program on ovulation rate and pregnancies per AI in Holstein heifers.

Listen in to hear the results and nuanced details of controlling reproductive structures using timed AI protocols.

Topics of discussion

1:03 Production costs of heifer rearing - survey results 2:09 Introduction of Dr. Fabio Lima 3:46 Description of the project 4:20 TAI protocol description 5:31 Varying GnRH dose 6:34 What is the function of GnRH in the heifer? 7:51 Hallmark of a successful synchronization 8:24 Results of ultrasound (ovulation) and P4 blood sample analysis 10:04 Did increased ovulation translate into improved pregnancy outcome? 10:44 Pregnancy at d47, 100% sex semen discussion 13:41 Relationship of Luteinizing hormone and progesterone 15:16 What causes elevated circulating progesterone 16:30 How did we land on 2cc of GnRH to begin with? 18:34 Does increased GnRH cause increased twinning? 21:02 What do you want boots on the ground dairymen to know 23:01 What if you cherry picked? 23:32 Sometimes the plan doesn’t work – but that’s why we do research! Featured article: Effect of 200 μg of gonadorelin hydrochloride at the first GnRH of a CIDR Synch program on ovulation rate and pregnancies per AI in Holstein heifers

Articles also discussed in the podcast: Heifer study using 100 and 200 ug in 5-d CIDR Synch protocol. https://doi.org/10.1016/j.theriogenology.2023.04.026

Studies showing the implication of progesterone for double ovulation (a proxy for twining) and progesterone. https://doi.org/10.3168/jds.2018-14410

#2xAg2030; #journalofdairyscience; #openaccess; #MODAIRY; #gnrh; #CIDRsync; #twinning; #pregnancy; #heiferdevelopment; #TAI; #lutenizing; #dairysciencedigest; #ReaganBluel;