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Newsletter of Penn Dutch Cow Care

February 2008

Hi Folks,

Within the past month there has been new information generated from the DHIA survey study that was completed last year. I’d like to share some more results with you in this newsletter.

Reproduction is the focus of the latest information. As an aside, my letter requesting to set up scheduled herd checks was sent out before this information came out. Remember that all the information shown is from directly the 30 herds here in Lancaster County that participated in the study. Both survey data regarding breeding program (seasonal or year round; AI or bull bred; vet checks for repro or no vet checks for repro, etc) as well as DHIA data is from the 30 herds and only those 30 herds. As there has never been a study done like this in the world, Dr. Ken Griswold (Extension dairy agent for Lancaster County) and I would like to extend our heart felt thanks to you who participated. Table 1 shows just the main results since there are simply way too many to fit in right here. Statistically significant differences, if any, between the types of breeding programs are shown with associated P value.

Item	All A.I.	A.I. @ 1st Service, Bull after	Hand-mate Bull	Free Running Bull	Significant Difference	P-value
Milk Yield, lbs/cow/year	17,697	16,687	14,355	13,832	Yes	0.0085
Milk fat, lbs/cow/year	655	629	566	541	Yes	0.0478
Milk protein, lbs/cow/year	528	498	453	433	Yes	0.0353

Act. Calving Interval, mo.	14.2	14.1	14.1	13.1	Trend	0.0510
Conception Rate, %	48.2	43.9	44.5	81.2	Yes	0.0007
Heat Detection Rate, %	46.0	46.6	46.1	20.4	Yes	0.0023
Pregnancy rate, %	15.3	17.6	16.5	22.8	Trend	0.063
Proj. Calving Interval, mo.	14.3	14.1	13.5	13.6	NO	0.2169
Days Open, days in milk	155	149	131	133	NO	0.2166

Days to 1st Service, DIM	95	94	82	93	NO	0.7007

Cows with < 40 days dry, %	7.6	3.8	6.0	19.6	Trend	0.0881
Cows with > 70 days dry, %	28.9	41.1	17.0	22.0	Trend	0.0648

Cows left herd, %	22.9	27.7	21.6	30.0	NO	0.4385
Cows left herd for reproduction, %	7.0	6.0	3.0	1.0	NO	0.2318

In the above table, it is clear that higher production herds use AI, have higher heat detection rates and also higher pounds of milk fat and protein. Herds that use only a free running bull have higher conception rates. This makes sense, however, in free running bull herds it is never truly known how many times the bull may have actually bred a cow before she settled. The pregnancy rate is conception rate x heat detection rate.

In Table 2, various items are shown and whether or not veterinary reproductive checks were done. As can be seen, higher producing herds incorporated regular veterinary reproduction checks (monthly or bi-monthly). This is NOT saying that having vet checks causes higher milk production - of course not. What it is saying is that higher producing herds have the veterinarian included as part of the general reproductive management program. This is probably due to more intensive herd management generally.

Table 2:

	Significance (P-value)
Item	No Service	Bi-Monthly	Monthly	Service vs. no service	Level
Milk Yield, lbs/cow/year	14,784	15,259	17,808	0.1612	0.0090
Milk fat, lbs/cow/year	557	587	660	0.1375	0.0312
Milk protein, lbs/cow/year	444	471	528	0.1268	0.0361

Act. Calving Interval, mo.	13.9	13.7	14.3	0.8089	0.0464
Conception Rate, %	65.3	57.0	46.0	0.1817	0.1518
Heat Detection Rate, %	25.8	36.7	45.4	0.0422	0.1185
Pregnancy rate, %	18.0	19.2	15.5	0.8088	0.0876
Proj. Calving Interval, mo.	13.6	13.8	14.4	0.1893	0.0488
Days Open, DIM	134	140	157	0.1868	0.0505

Days to 1st Service, DIM	92	92	97	0.7421	0.4424

Cows < 40 days dry, %	6.0	12.8	5.8	0.5757	0.2030
Cows > 70 days dry, %	41.8	25.8	32.9	0.1484	0.2572

Cows left herd, %	31.0	27.8	24.4	0.3338	0.3743
Cows left herd for reproduction, %	10.0	2.8	6.1	0.0621	0.1321

Notice the last line “cows left herd for reproduction”- herds with no vet checks had a bunch more. This may be due to uterine infections, cystic cows and “no heat noticed” cows not getting treated in a timely manner. Please remember that all information for this project was information supplied by the farmers from the 6 page survey and their own DHIA monthly data. Dr. Griswold and I did not insert or delete anything.

Dr. Griswold also found that there was a significant association between milk production and number of metabolic problems in a year (including milk fever, retained placenta, ketosis, twisted stomach). Additionally, there was a significant association between milk production and the number of regularly scheduled herd checks in a year. While it gets more technical than I can present here, it basically showed that there is a baseline milk production of 13,307 lbs among the organic herds in the survey. Of 15 factors associated with milk production, only 2 factors were strongly associated with increased milk production: (1) for each metabolic problem that occurred per year, there was an associated + 187 lb milk increase/cow/year on average and

(2) for every regularly scheduled herd pregnancy check per year there was an associated + 169 lb milk increase/cow/year on average. From this information, if a farmer were to have 6 herd checks a year (associated with a + 169 increase/cow/year on average) this yields + 1014 lbs increase/cow/year (6 x 169) on average. At $26/cwt, this is associated with a $264 increase/cow/year. Take $264 x 40 cows = $10,560 increase for the year on average. Doing 12 herd checks would be associated with an increase of +2028 lbs increase/cow/year on average. You can do the same math for the total amount of metabolic problems you have in a year and multiply by the associated + 187 to see what the associated production would likely be on average. These numbers are the averages from all the herds in the study – there will be some variation within specific herds. I know this probably all sounds very self serving by me, but these are your DHIA numbers and your answers to the survey that you filled out. Dr. Griswold simply put the numbers into “the tumbler” (the computer) and this is what happened to come out. We honestly had no idea of what the outcome would be. Why are metabolic problems positively associated with milk production? Probably because the cows are being pushed just a touch more and these problems may occur. In conclusion, are having a few metabolic problems or having regularly scheduled herd checks worth the cost to the farmer? I’ll let you decide.

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