Sunday, March 31, 2013

Buying Hoof Blocks

Can you just buy the cheapest blocks? No. Buy a minimum density, or at least only buy blocks that sink. Full explanation below.

I'm assuming here that you treat your own lame cows as a general rule. I'm assuming you've done some training at some point (eg learnt from other farmer, trimmer, vet, or a course eg with Karl Burgi) and you regularly use hoof blocks. I'm assuming then you also buy the supplies. There's of course a number of places to buy your supplies (in alphabetical order), eg  Camden Cow Clogs, Genetics Australia, Innovative Farm Imports, Shoof and others.

Proper hoof trimming is a discussion of its own, and not covered here. Proper equipment for hoof trimming is also another discussion of its own, ranging from basic (Shoof vet rope and lifter tied to current crush), to dedicated crushes, such as WOPA and Comfort Chutes. For safety's sake (trimmer and cow), only people who know what they are doing should trim.

Glue is a whole discussion of it's own. As far as I can tell, Bovi-bond is one of the oldest glues/adhesives. I get 5 cows per tube (180ml), although being a bit more stingy could probably get me 6. Other products I've used - Easy Bond and Quick Block are similar in consistency, with similar style mixing tips. Camden cow clogs has a larger tube, with a thinner consistency, and its own mixing tip. To be honest you would need a randomised trial with a fairly large sample size to tell the difference in glue "staying power". Any else is probably just opinion or anecdotal.

Hoof Blocks is what I promised to talk about. I am a fan of wooden blocks. I think wood gives a more natural feel for the cow than rubber. Wooden blocks come in all sizes and patterns. I think scores help the glue staying power, and most blocks have this. I know there are various grades of wood, with varying density. The denser the better I say, and I'll go through this below in case you aren't convinced. This link gives a rough idea for Australian woods, where roughly speaking, density is correlated with increasing hardness, toughness and durability.

Below is a picture of a selection of blocks bought from various suppliers.

You can't assume that the darkest wood is the densest/hardest, although it is correlated. The weight is written on the side in grams. Of course that is not a good guide either, because the size and shape vary. Thanks to some experimental work attributed to some Greek bloke called Archimedes, I determined the volume of each block and then calculated the density (g/ml, or equivalently, kg/l). They varied from 0.76 to 1.21. Water's density is 1 (by definition, thanks metric system!) , so anything denser sinks (eg first picture), and less dense floats (eg second picture, me holding it down). Note, I also measured the blocks after submerging in water, and the denser blocks added less weight (about a gram) versus 5 or more grams for less dense blocks.

Why am I banging on about density and hardness? Let me show you some pictures of a block I took off a cow, to put a new one on. This had been attached to the cow, walking some decent distances, for 21 days. It was fairly worn as you can see. It had a density of 1, measured in its current state. Clearly a less dense block would have disentegrated by now.

Perhaps more importantly, look at the top surface (picture below). You can see dark areas where the glue was not adhering to the surface any more. I strongly suspect that less dense blocks lead to water soaking through the wood (as evidenced by post soaking weights), reducing the glue adherence, leading it to fall off earlier. When you consider the time and other material costs of treating a lame cow, you shouldn't skimp on the block, but demand from your supplier blocks that sink, and send back any blocks that float. 

Tuesday, March 12, 2013

Ben Gate developments

For an overview of the Ben Gate, click here.

I'm talking (writing) here about BreakAway, Buying other parts to put Ben Gates together, and Getting started on the advanced version  (Ben Gate 2.0) for people with no Arduino or hardcore electronics experience.

A common question about the Ben Gate is whether it will break under pressure - eg cow or person pushing through the wire. I initially used second hand tape, so that would break instead. However, there exists a good solution, originally described by Robert Cavarsan in the original FarmSmarts book, and as presented on the New Inventors. As I understand it, the design has been changed to have the breakaway part in the anchor. He has been selling them through his website here (currently down).

I envisage it would look something like this (inspired by the break away clips on our cup removers).
This demo used a standard wood post insulator, an r clip (sometimes called humpback pin) and a washer to encourage the hook to be put in the right place. Video of example here.

Buying parts to put together
One of the parts I use is a reel (or spool) to windup the wire. I make this out of old plastic 200l drums, with circle cutters. What if you were in a hurry? Maybe you've heard about the 3D printing revolution - you just print one! I made a mockup that you can see here, and print at (for example, I.materialise) and get delivered to your door. It even has printed smartly on the edge if you rotate in the 3D view. Ideally it will have holes to put bolts straight through to the aluminium hub (on the parts list), but really you could just put screws through the hub into the spool. Pololu have a mount for the motor which would make it easier to put together and stronger, and I think it fits the motor specified in the parts list - mount listed here.

The next useful part for the Ben Gate 2.0 would be a custom PCB, or printed circuit board. I haven't done that before, but imagine if you will, to reduce and simplify wiring, you just plug the components on the part list into the custom board, screw into the enclosure and away you go. If you are keen for this, let me know and I'll have a crack - queued behind some other work.

Another useful thing is the Arduino code to run Ben Gate 2.0. Again, I'll be making this available free, but I'm currently tidying up the code so it will be clearer to understand. My code is based originally on this example available here.

Look out for some new options coming, as requested at the conference.

Getting started on Ben Gate 2.0
Read Getting started with Arduino, described here, and have an Arduino and some parts to play with. It's easy to read, and examples are easy to follow. From there you will be well on your way. Download my code, upload to your Arduino, and assemble the hardware.

Once you've done that, you'll be thinking up your own improvements. Try incorporating Status LED's or go the extra mile - mobile phone control! Eg this or this, or do it old school with this and this.

Heifer Synchronisation

So you have a batch of heifers you want to AI, but it's not convenient to AI every day at your dry block or out block every day for a month. Then you want some form of synchronisation.

Timboon Veterinary Group have an excellent overview of the options here. I highly recommend reading that first. Another source of protocols is here from ABS.

We usually AI about 100, once or twice a year, followed by a period with the bull. This batch size give us some confidence in the results here, although non pregnant are rolled in to later batches, so samples are not precisely random.

Previously we have done the PG AI (as descried by the TVG link above), and followed the next week with a PG AI on the remaining unjoined heifers for a 90% submission, for 10 days of "yarding" (ie rounding them up and putting through the yards). Ten days of yarding is a hassle when you have other time critical jobs to do.

The last two batches we have used the double PG option, with an 85% submission, followed by a 75% submission, for 6 days of "yarding".

However, pregnancy is what we are after. So you need to multiply your submission rate by your conception rate. Unfortunately conception rate is going to vary by farm and operator and season, so comparability is a problem. The second last batch, where we have calves to confirm preg test data, showed 56% conception to AI, to give 47% of calves to AI (ie just under half).

The bulls went in after a days break post AI, and stayed for 7 weeks, long enough for them to get 2 cracks at returning from AI. With synchronised animals, bull power can be an issue if not enough are pregnant, as many are coming back at the at the same time. 15% weren't AI'd, so could cycle anytime, so not an issue for bull power. The other ~35% would have cycled close together, but the bulls conception rate was ok at 66%, to give an overall pregnant rate of 78%.

Why not leave the bull in longer? We want the vet to be able to distinguish age accurately, so for preg testing 6-7 weeks after the bulls are out, but before too long has elapsed (ie foetus 3 or more months old). Plus, who wants to drag out calving if there is another batch not too far in the future?

Why not use CIDR's or equivalent devices? Certainly they will be tightly synchronised, but AI'ing too many in a day might lead to a reduction in operator conception rate, and bulls spread too thin for returns. For smaller batches, I see it could be an attractive option.

Another alternative used overseas is MGA omelengesterol acetate, which is fed for a period beforehand. I have not heard of it used here in Australia. A protocol is described here. Anyone with experience, let me know.