GSL Beef Physiology Research Update

Dr. Rick Funston Author

09/03/2020 Added

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Dr. Funston discusses new research out of his lab.
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[00:00:02.150]This is Rick Funston
[00:00:03.140]with the University of Nebraska.
[00:00:06.730]At the Annual Gudmundsen Sandhills Laboratory Open House,
[00:00:11.320]in some different format
[00:00:13.150]than I've experienced today
[00:00:15.620]but nonetheless thank you all for getting online
[00:00:21.390]and listening to the presentations this far.
[00:00:25.660]You're all familiar
[00:00:26.493]with the Gudmundsen Sandhills Laboratory.
[00:00:28.340]We've a composite herd that's Red Angus Simmental.
[00:00:32.250]And then for each resource that's upland range
[00:00:35.700]or sub-irrigated meadow,
[00:00:37.460]which really compliments grazing.
[00:00:41.580]Because we have two different grass varieties
[00:00:46.210]that have different growth patterns as shown in this slide
[00:00:50.810]and different forage quality both in crude protein
[00:00:55.110]and in energy.
[00:00:57.450]This is years of data that Don Adams
[00:00:59.870]was the instrumental in collecting
[00:01:01.660]to put together some of these plant nutrient profiles
[00:01:06.280]throughout the year.
[00:01:07.630]And the questions become how do we both take advantage of
[00:01:13.550]or deal with those changes in forage quality?
[00:01:17.080]Especially if we want to remain profitable
[00:01:20.270]and decrease feed cost,
[00:01:22.810]which is the largest cost we have in beef production.
[00:01:26.740]We ask ourselves, what are the implications
[00:01:30.120]of grazing animals in a system that the forage quality
[00:01:34.660]is below their requirements,
[00:01:36.460]not only for the animal that's grazing
[00:01:38.570]but in the animals that are subsequent progeny
[00:01:42.010]in both the steers clear through the feedlot
[00:01:44.960]in the heifer calves as measured in fertility and growth
[00:01:48.560]and feed efficiency for example.
[00:01:52.390]Well one of the biggest decisions a ranch has to make
[00:01:55.990]is when they calve,
[00:01:57.820]because it has far reaching implications
[00:02:02.020]on the entire system.
[00:02:05.720]And I wanna highlight one of our calving herds
[00:02:09.640]in three studies that were conducted
[00:02:11.860]in finishing up at Gudmundsen.
[00:02:15.220]One of the things we must consider
[00:02:18.410]when we change calving time,
[00:02:20.310]how does it affect winter feed requirements?
[00:02:22.460]That was some of the biggest impetus to calve later
[00:02:26.020]when Don Adams research
[00:02:28.010]was to decrease harvested forage needs.
[00:02:32.230]And feed costs obviously are the number one cost
[00:02:35.610]in any ranch operation.
[00:02:38.860]And can we utilize range forage more
[00:02:42.190]as we changed calving date?
[00:02:44.680]But how does that affect both cow
[00:02:46.700]and calf productivity at weaning and post weaning?
[00:02:50.350]And do we need to consider
[00:02:52.090]alternative post weaning strategies
[00:02:55.160]for those calves born in later calving systems.
[00:02:59.630]But the bottom line is it's not all about outputs.
[00:03:03.230]Some of the early calving work shows
[00:03:05.910]heavier weaning weights.
[00:03:09.020]Different weights going into and out of the feed lot.
[00:03:15.590]But what about overall profitability which
[00:03:18.280]not just considers output but also inputs.
[00:03:21.830]So, four main factors that we think about
[00:03:26.990]as we change calving.
[00:03:28.860]Harvested feed is lowest if we calve later.
[00:03:31.970]Bad weather challenges are lowest as we calve later
[00:03:36.150]but weaning weights are lower as we calve later.
[00:03:38.950]And then labor it depends on the operation,
[00:03:41.680]could be a conflict as we're calving later
[00:03:44.030]if it interferes with other things on the ranch
[00:03:48.140]that we need labor for.
[00:03:49.930]But the two biggest factors I think that people consider
[00:03:53.520]when they choose a calving season is weather
[00:03:59.190]and then labor.
[00:04:00.350]Because a lot of these ranches don't have facilities
[00:04:03.680]to deal with storms
[00:04:05.550]and one person that is calving a lot of animals
[00:04:09.820]on some of these larger ranches.
[00:04:13.360]We've always since I started work here
[00:04:17.120]had more than one calving season.
[00:04:19.700]We had a June and March when I began.
[00:04:22.660]Through the years we've calved in,
[00:04:25.070]always had a March herd
[00:04:26.810]and then we had a March, June and August
[00:04:28.880]and have some nice data published with that, comparisons
[00:04:32.010]and different post weaning management strategies.
[00:04:35.750]And then currently we have a May and a March calving herd.
[00:04:39.970]So what are the opportunities?
[00:04:41.520]Well, why would you calve later?
[00:04:43.410]And we talked a little bit about it
[00:04:45.070]but if we look at matching forage,
[00:04:46.850]highest requirements of the cow
[00:04:49.550]are early lactation.
[00:04:51.570]And oftentimes we may not have very good quality forage
[00:04:56.910]during early lactation
[00:04:58.320]if we calve real early before the forage comes on.
[00:05:01.850]So early lactation in this May calving system
[00:05:06.310]has high protein and energy.
[00:05:09.300]And we can potentially take advantage of that
[00:05:12.680]and recover any body condition
[00:05:14.730]or body weight changes over winter
[00:05:17.930]due to not supplementing
[00:05:20.840]and decrease our harvested feed needs.
[00:05:24.660]Severe weather, as I mentioned before,
[00:05:26.840]challenges are much less as we have later.
[00:05:31.230]Breeding occurs during a period of the highest
[00:05:34.470]or higher ambient temperatures.
[00:05:37.500]From our work done with calving in March, June
[00:05:40.440]and August with cows that have had multiple calves,
[00:05:44.920]no difference in pregnancy rates.
[00:05:47.120]So, a lot of people worry about the heat,
[00:05:50.770]I think heat and humidity become the issue.
[00:05:53.670]And generally at least in this area in Nebraska,
[00:05:58.430]it cools off at night so they get relief from that heat
[00:06:01.610]and I think the heat becomes a much bigger factor
[00:06:05.420]as we go to the Southeast.
[00:06:07.600]The one that is a challenge I believe
[00:06:09.550]is this declining forage quality
[00:06:11.400]during the breeding season
[00:06:12.650]as we calve later and breed later.
[00:06:16.040]And it's been implicated to increase embryonic loss
[00:06:19.780]and decrease conception rates.
[00:06:22.210]So from previous work in this first bullet
[00:06:25.660]was the March, June, August,
[00:06:27.730]we saw again no difference in preg rates
[00:06:31.020]for cows that have had multiple calves,
[00:06:34.230]regardless of when the breeding season was.
[00:06:37.400]We did see though that heifer calves from a May calving herd
[00:06:42.500]had lower pregnancy rates,
[00:06:44.520]than from our March calving herd.
[00:06:47.320]So what are potential management strategies
[00:06:51.200]to overcome some of these challenges?
[00:06:53.360]Well supplementation might be one,
[00:06:55.770]although probably not the number one pick
[00:06:59.050]to go supplementing cattle during the summertime.
[00:07:01.610]But we looked at, did we have enough
[00:07:04.730]to supplement cattle during the breeding season
[00:07:08.330]in this May calving heifers and first calf heifers.
[00:07:12.950]So we wanted to look at preg rates
[00:07:14.550]and then body weight and body condition.
[00:07:17.220]And what did it do to the weights of the calves
[00:07:20.850]that were on the first calf heifers.
[00:07:23.080]Well we had body weight increase in heifer calves
[00:07:27.330]that received supplement as body condition followed
[00:07:30.920]but no difference in puberty or pregnancy rates.
[00:07:36.140]On the first calf heifers,
[00:07:37.700]we saw a response in body weight
[00:07:40.580]and body condition if we supplemented
[00:07:43.350]but again no difference in pregnancy rates.
[00:07:45.860]So no great benefit to supplement during the breeding season
[00:07:50.500]on the outcome that we were trying to manage
[00:07:54.010]which wasn't necessarily body weight
[00:07:55.980]but it was pregnancy rate.
[00:07:58.290]Calf body weight was increased in the first calf heifers
[00:08:01.580]that received supplement
[00:08:02.670]whether it was direct through milk
[00:08:06.220]or eating the supplement or milk production
[00:08:09.650]or a combination of both probably.
[00:08:13.360]So supplementing this supplement that was high
[00:08:15.940]in undergradable protein,
[00:08:18.270]increased weight and body condition
[00:08:21.140]but did not impact pregnancy rates
[00:08:24.310]which was the outcome we were looking for.
[00:08:28.410]Some other protein sources that are being looked at
[00:08:31.500]involve more rumen degradable protein
[00:08:34.860]and potentially this could elicit a different response
[00:08:40.070]possibly than a high undergradable protein.
[00:08:44.545]The other thing we have to manipulate
[00:08:48.300]or utilize is different forage types in the Sandhills.
[00:08:52.410]So can we take advantage of these to overcome
[00:08:55.730]any potential detrimental effects
[00:08:58.440]of these later breeding seasons?
[00:09:01.290]So we had both heifers and first calf heifers again
[00:09:04.740]but then we had multiparous cows
[00:09:07.480]that have had multiple calves.
[00:09:09.730]And then their treatments were either meadow or range
[00:09:12.050]with or without supplements.
[00:09:15.120]If we look at this one year of nutrient analysis
[00:09:17.720]as agreed with the early slide,
[00:09:20.710]protein is higher in the meadow
[00:09:22.670]but interestingly energy was pretty similar
[00:09:26.130]and followed a fairly similar pattern on the meadow
[00:09:29.250]and the upland range.
[00:09:31.440]If we look at body weight response,
[00:09:35.280]we start with the top two lines
[00:09:37.120]which are the multiparous cows.
[00:09:40.320]We did get a response to supplementing
[00:09:42.540]during breeding on body weight
[00:09:44.740]in all three classes of animals.
[00:09:46.860]The first calves in the middle
[00:09:48.260]and then the heifer calves on the bottom.
[00:09:52.210]But again, we did not see a benefit on pregnancy rates,
[00:09:59.120]for any of the classes of animals
[00:10:01.760]that were either grazing the two grazing systems
[00:10:06.410]or supplemented or not within those systems.
[00:10:13.970]The Calf-at-side we saw heavier calves
[00:10:21.730]from the multiparous cows
[00:10:25.520]and we also did see heavier calves
[00:10:29.320]from the cows that were supplemented
[00:10:31.280]as we saw in the previous study.
[00:10:37.960]So, forage analysis we had higher protein,
[00:10:42.030]similar energy,
[00:10:45.060]we did increase body weight, by supplementing
[00:10:48.890]and calf weaning weight
[00:10:50.350]but we'd saw no difference in pregnancy rates again.
[00:10:55.100]So the last of the studies
[00:10:56.830]really builds on some more that we looked
[00:11:01.460]at the need to supplement cattle in a March calving system
[00:11:06.017]and during winter grazing
[00:11:07.950]and how did that impact future productivity
[00:11:12.950]of both the steer and heifer progeny?
[00:11:15.940]Like I mentioned earlier,
[00:11:18.090]the May calving system,
[00:11:20.450]we have a much different nutrient environment
[00:11:22.880]immediately before calving
[00:11:24.660]for sure than we do in the March system.
[00:11:28.800]So, we've seen negative effects
[00:11:31.040]from not supplementing in the March calving system
[00:11:36.400]during winter grazing.
[00:11:38.580]The forage is different though in the May herd
[00:11:41.300]as I mentioned, going to be different during late gestation.
[00:11:49.090]So, we're hypothesizing that this difference in forage
[00:11:54.680]in consequently nutritive value
[00:11:57.490]will affect re-breed pregnancy rates
[00:11:59.360]and alter progeny postnatal growth and performance,
[00:12:03.110]perhaps in a different manner
[00:12:05.200]than in our March calving system.
[00:12:07.840]So we wanted to look at again a similar model,
[00:12:11.310]two forage types with and without supplementing
[00:12:14.520]in late gestation on our May calving dams.
[00:12:18.170]On both their individual performance
[00:12:21.257]and pregnancy rates
[00:12:23.000]and then the progeny postnatal growth
[00:12:26.390]and the heifer reproductive performance.
[00:12:30.730]In this sphere it's clear to slaughter
[00:12:32.680]fed out here at North Platte.
[00:12:34.700]The dam results we saw
[00:12:40.210]approaching significance negative effect in the range,
[00:12:44.670]no supplement group.
[00:12:47.490]So, a decrease in pregnancy rates
[00:12:50.570]if we didn't supplement that cow grazing native range.
[00:12:54.820]But if you look at the both meadow
[00:12:57.300]and the range supplement are quite similar.
[00:13:02.430]So body weight was lowest in the range.
[00:13:04.840]No supplements,
[00:13:05.770]the other treatments were similar,
[00:13:07.300]conditions were followed.
[00:13:12.830]The meadow grazing tended to increase pregnancy rates.
[00:13:22.350]The steer progeny late gestation nutrition had no impact.
[00:13:27.810]Heifer progeny, there was an interaction
[00:13:32.040]between the pasture type and supplementation.
[00:13:38.090]So, somewhat difficult to explain
[00:13:42.010]but no difference in pregnancy rates
[00:13:44.600]when she was bred as a yearling heifer.
[00:13:50.810]With no differences in gain on the steers
[00:13:54.250]but there are some reported differences in the heifers.
[00:13:57.880]Why difference in steers and heifers,
[00:14:00.880]while there's other species
[00:14:02.440]that show some sex specific responses
[00:14:06.480]and it's likely an interaction of hormones
[00:14:12.160]and in gestational treatment,
[00:14:14.610]which the females and males responded differently.
[00:14:20.380]If we look at the heir
[00:14:21.640]then re-breeding of the heifer after she had her first calf
[00:14:26.390]interestingly, our preg rates were lower
[00:14:30.290]in the two range systems.
[00:14:33.140]So why this lag that we had no difference
[00:14:37.940]in initial pregnancy rates
[00:14:39.950]but in our first calvers
[00:14:42.190]after they heard a calf preg rates were greater
[00:14:46.060]in those that were on meadow,
[00:14:48.800]that came from a cow that was on meadow during gestation.
[00:14:55.850]So with that and that out of time,
[00:14:58.290]if there are any questions
[00:14:59.310]feel free to contact me
[00:15:00.660]or type them in the chat box.
[00:15:02.310]Thank you for attending.

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GSL Beef Physiology Research Update

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