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The performance of Holstein Friesian dairy cows of high and
medium genetic merit for milk production on grass-based
feeding systems
a,b b ,
*
b b aF. Buckley
, P. Dillon
, S. Crosse , F. Flynn , M. Rath
a
Department of Animal Science, Faculty of Agriculture, University College Dublin, Belfield, Dublin 4, Ireland
b
Dairy Husbandry Department, Teagasc, Moorepark Production Research Centre, Fermoy, Co. Cork, Ireland
Received 24 July 1998; received in revised form 6 October 1999; accepted 29 October 1999
Abstract
The effect of cow genetic merit on the performance of spring calving Holstein Friesian dairy cows in first, second and third lactation was investigated. The study contained 96 first lactation animals in 1995, 96 second lactation animals in 1996, and 72 third lactation animals in 1997. Half of the animals were of high genetic merit (HG) and half of medium genetic merit (MG) for milk production. Genetic effects for the traits of interest were estimated as the contrast between the two genetic groups. The HG cows produced significantly higher yields of milk, fat, protein and lactose when compared to the MG cows. During the grazing season the HG cows had significantly (P,0.001) higher grass DM intake (GDMI). In very early lactation when cows were indoors, offered grass silage ad libitum plus 7.9 kg of concentrate DM daily, there was no difference in DM intake. During the non-lactating period the HG cows had significantly (P,0.01) higher silage DM intake (SDMI). Cow genetic merit had no significant effect on live weight with the exception of pre-calving weight at the beginning of second lactation when the HG cows had significantly (P,0.05) higher live weight. At all stages of lactation the MG cows had significantly (P,0.001) higher condition score. In early lactation the HG cows had greater (not significant) live weight loss and significantly (P,0.05) greater condition score loss (indicating greater negative energy balance). In the dry period the HG cows had significantly (P,0.01) greater live weight gain. The results of this study suggest that present day HG cows will produce high milk yields on a grass-based feeding system where an adequate quantity of high quality grass is available. 2000 Elsevier Science B.V. All rights reserved.
Keywords: Dairy cows; Genetic merit; Grass; Milk production
1. Introduction duction in dairy herds in the UK and the Republic of
Ireland up to 1985 was relatively slow, particularly The rate of genetic improvement for milk pro- in contrast to that achieved in North America where genetic merit for milk production has increased by over 150 kg per year in the Holstein population *Corresponding author. Tel.: 1353-25-42250; fax: 1
353-25-(Funk, 1993). However since then changes in EU 42340.
E-mail address: [email protected] (P. Dillon) legislation has allowed greater access to world
genetics, and, in the past 10 years, has resulted in 2. Materials and methods
rapid genetic improvement in UK and Irish dairy
herds. This resulted in a rate of genetic improvement 2.1. Genetic groups of 2.2% per year between 1990 and 1994 (Lindberg
et al., 1998). Two groups, containing 48 cows each, initiated the
A number of studies have investigated the per- study in 1995. The high genetic merit group (HG) formance of high genetic merit cows on feeding were imported from Holland and France as in-calf systems based on ensiled forages and relatively large heifers in 1994. The medium genetic merit group amounts of concentrates (Veerkamp et al., 1994; (MG) were assembled from the Moorepark herd. Gordon et al., 1995). However, little information is Mean predicted differences (PD) and standard devia-available on the performance of present day high tion (S.D.) within each group for milk yield, fat genetic merit cows on seasonal calving, grass-based yield, protein yield, fat concentration and protein systems like those commonly in use in Ireland concentration were; 1475 kg (76), 116.7 kg (2.4), (Dillon et al., 1995). There are, for instance, con- 115.6 kg (1.3), 20.16 g / kg (0.70) and 20.02 cerns that the negative energy balance found on other g / kg (0. 25) for HG and 1140 kg (68), 19.7 kg feeding systems is exacerbated on grass-based sys- (3.5), 17.0 kg (2.5), 10.84 g / kg (0.68) and tems as these systems depend to a large extent on the 10.48 g / kg (0.34) for MG. The PDs for each cow conversion of grazed grass to milk with little extra were calculated as 0.503sire PDs, plus 0.253
concentrates fed. maternal grand sire PDs. The PDs of the sires and
The term used for animals performing well in one the maternal grand-sires came from the August 1997 system of production, and not necessarily being able international proofs of the Animal Centre in Uppsala, to hold the same advantage in another feeding Sweden using the technique known as MACE (Mul-system, is genotype3environment (G3E) inter- tiple-trait Across Country Evaluation) (Schaeffer and action (Peterson, 1988; Graham et al., 1991). If there Zhang, 1993), with no Moorepark records included. is evidence of G3E, then there is no indication of The sires of cows in both the HG and MG had at how progeny of a particular sire will perform in a least 75 daughters in at least 70 Irish herds contribut-feeding system very different to that in which it is ing to their MACE proofs with a reliability of greater tested. This study contains three environments and than 90%.
two genetic groups (high and medium genetic merit, Animals of similar genetic merit and lactation HG and MG, respectively). The grouping of cows in number replaced animals culled after the 1995 genetic groups is based on sires breeding values. The grazing season. Replacements were not available in sires of the cows had Interbull-breeding value-based 1997 to replace animals culled after the 1996 grazing large daughter groups outside Ireland and more than season. Therefore this study contained 96 first lacta-75 daughters in Ireland itself. The environments tion animals in 1995, 96 second lactation animals in were three different grass based feeding systems 1996, and 72 third lactation animals in 1997. (Buckley, 1998) carried out at Teagasc Moorepark
over 3 years. It is important to establish the effects of 2.2. Grass-based feeding systems increased genetic merit on milk production, grass
intake, condition score and live weight change on A permanent grassland site was used consisting of production systems based on grazed grass. We can a sward with almost 100% perennial rye grass thus establish possible benefits of using improved (Lolium perenne). The grazing season extended from genetics, and to anticipate possible changes in man- early March until late November each year. Cows agement or feeding practices that may be necessary. were housed full time for the months of December, In this paper the effect of genetic merit on milk January and February. The breeding season each production, intake, live weight and condition score year was confined to 13 weeks. It started in late on production systems based on grazed grass will be April and ended in late July. Therefore most of the
During the winter indoor period while animals respectively. In the second and third year the HG and were dry, animals were offered grass silage ad MG cows had similar mean calving dates of Feb-libitum. First lactation animals were given a 10-week ruary 22 and 24, respectively.
dry period while in subsequent lactations 8 weeks was considered sufficient. Post-calving and prior to turnout to grass (early March) all animals were
offered grass silage ad libitum and a standard 2.3. Silage and concentrate supplementation allowance of 7.9 kg of concentrate DM daily.
On turnout to pasture, animals were grazed on a Two concentrates with different ingredient mix-rotational management system (Dillon et al., 1995). tures were offered during the experiment. The in-Pre-grazing herbage yields were maintained at be- gredient composition (kg / t) of the concentrate of-tween 1800 and 2200 kg DM / ha (.4 cm). Daily fered immediately post-calving until mid-April was concentrate supplementation decreased to 5.3 kg DM unmolassed beet pulp 240, barley 200, maize gluten at turnout up until mid-April. In mid-April each year 350, rapeseed meal 100, fish meal 75, lard 20 and the cows were grouped into blocks of three within minerals and vitamins 15. The concentrate fed for each genetic group on the basis of calving date and the remainder of the year contained (kg / t) unmollas-milk yield. Animals within each block were random- sed beet pulp 510, maize gluten feed 220, barley ly assigned to one of three feeding systems (Buckley, 100, lard 10, soya 120 plus minerals and vitamins 1998). Feeding system A incorporated a high stock- 40. All concentrate feeding was offered in individual ing rate (3.0 cows / ha), high nitrogen fertilization stalls in the milking parlour in two equal feeds each rate (380 kg N / ha) and a planned concentrate input day.
2.4. Sward measurements was also measured on three other occasions during the 3-year experimental period. In 1996, individual When cows were outdoors full time, both geno- animal intake was estimated on 40 second lactation types were grazed separately within each feeding cows (20 HG and 20 MG) in late December during system. Each paddock had a clearly defined 50:50 the non-lactating period while indoors on grass silage dividing line. Using a temporary electrified wire, it only. Individual animal intake was also estimated in was possible, based on previous post-grazing sward early lactation on 33 third lactation cows (13 HG and surface height, to allocate a different area to each 20 MG) in early March, 1997, while cows were genetic group, while maintaining the same post- indoors fulltime and offered silage ad libitum plus grazing height. In each paddock a total of 40 pre- 7.9 kg DM of concentrates daily, and on 34 third and post-grazing sward surface heights were re- lactation cows (16 HG and 18 MG) in late March, corded (20 in the HG and 20 in the MG section) 1997, when cows were at pasture fulltime and using a sward stick (Hutchings, 1991). supplemented with 5.3 kg DM of concentrates daily.
Pre-grazing herbage yield (above 4 cm horizon)
was determined on each grazing paddock based on 2.6. Chemical analysis four strips of grass cut with an Agria mower (0.95 m
wide, 7 to 9 m long). The grass from each strip was The freeze-dried pre-grazing herbage samples weighed, sampled and a sub-sample was dried were composited for each treatment for each week of overnight at 908C for dry matter (DM) determi- the experiment and analysed for organic matter nation. The remaining herbage from the four samples digestibility (OMD) (Morgan et al., 1989), Kjeldahl from each paddock was bulked and a sub-sample nitrogen and modified acid detergent fibre (MADF) taken. This sample (ca. 100 g) was freeze-dried and (Clancy and Wilson, 1966). Similarly in periods of used for chemical analysis. silage supplementation, a composite grass silage sample for each treatment for each week was ana-2.5. Animal measurements lysed for residual moisture, pH, dry matter diges-tibility (DMD) (Tilley and Terry, 1963), Kjeldahl Throughout the 3 years, individual cow milk yield nitrogen, MADF and ash.
was recorded on 5 consecutive days / week. Milk fat, Concentrates were sampled weekly, bulked over protein and lactose concentration were determined in each 3-weekly period, and analysed for DM, total one successive morning and evening sample of milk / nitrogen, crude fibre, neutral cellulase gammonase week using a Fos-let instrument (AS / N Foss Elec- determination (NCGD) (AFRC, 1993), oil and ash. tric, Denmark). Live weights were recorded weekly
and condition score (Jefferies, 1961) once every 3 to 2.7. Statistical analysis 4 weeks.
Individual animal intake was measured on all The animal production data were analysed by cows on 11 occasions while at pasture over the 3 procedures for a factorial arrangement of treatments years of the study using the n-alkane technique of using the statistical procedures of SAS (Statistics Mayes et al. (1986), as modified by Dillon and Analysis Systems Institute, 1991). The model used Stakelum (1989). In 1995, intake estimates took was:
place in early May, mid-June, late July and early Y 5G 1F 1B 1(G3F) 1e ijkl i j k ij ijkl November, corresponding to 87, 129, 171 and 269
Table 1
Chemical composition of grass, grass silage and concentrate offered over the 3 years
Grass Grass silage Concentrate
Crude protein 209 32.4 159 11.0 198 27.2 201 0.6 169 6.1
Crude fibre – – – – – – 84 13.6 108 11.9
Modified acid detergent fibre 208 21.3 314 42.6 262 57.7 – – – –
NCGD – – – – – – 822 8.5 841 2.5
The effect of cow genetic merit on pre- and post-grazing sward surface heights (cm) over the 3 years
a
HG MG S.E.D. Sig.
Pre-grazing sward surface heights 20.0 20.0 0.35 NS
Post-grazing sward surface heights 6.6 6.7 0.10 NS
a
S.E.D., standard error of difference; NS, not significant (P,0.05).
3. Results the silage offered while indoors and during periods
of grass shortage throughout the grazing season, 3.1. Sward measurements respectively. Concentrate 1 and 2 refer to the con-centrate offered up until mid-April and the remainder Table 1 shows the average chemical composition of the year, respectively.
of the grass, grass silage and concentrate offered Table 2 shows that the herbage allocated to both over the 3 years of the study. Silage 1 and 2 refer to genotypes was of similar pre-grazing height and that
Table 3
The effect of cow genetic merit on milk production over three lactations
First lactation Second lactation Third lactation (26 weeks) Significance
a
HG MG S.E.D. HG MG S.E.D. HG MG S.E.D. 1st 2nd 3rd
Yields(kg / cow)
Milk 6441 5496 119.1 7779 6862 131.5 6199 5499 148.0 *** *** ***
SCM 5895 5286 110.6 7209 6482 120.9 5548 5147 128.7 *** *** **
Fat 241 222 5.5 302 274 6.2 228 217 5.9 ** *** *
both genotypes grazed to similar intensity over the quality grass on a daily basis over the 3 years grazing season. The area allocated to the HG cows (Stakelum and Dillon, 1990).
was on average 5 to 6% greater than that allocated
the MG cows to achieve similar post-grazing heights. 3.2. Milk yield and composition Both the chemical analysis of the herbage and the
post-grazing sward surface height suggest that the Table 3 shows the effect of cow genetic merit on cows had access to adequate quantities of high milk production during first, second and third
tion. The HG cows produced significantly higher HG cows had a significantly (P,0.01) higher SDMI yields of milk, solids corrected milk (SCM) (Tyrrell during the non-lactating period (Table 5). In very and Reid, 1965), fat, protein and lactose during all early lactation when offered grass silage ad libitum three lactations. With the exception of the second plus 7.9 kg DM of concentrates daily there was no lactation the MG cows produced milk of significantly difference in SDMI between the HG and MG cows higher fat and lactose concentrations. There was no (Table 5). However, with a separate group of cows effect of cow genetic merit on protein concentration. that were turned out to pasture in very early lactation Estimated total lactation milk yields (kg) as third and offered 4.4 kg DM concentrates daily the HG lactation animals would have been 8758 and 7610 cows had significantly (P,0.05) higher GDMI for the HG and MG cows, respectively (Farrell, (Table 5).
1998). This corresponds to a difference in total
lactation yield (kg) between the genetic groups of 3.4. Live weight and condition score 948, 917 and 1148 for first, second and third
lactations, respectively. Table 6 shows the effect of cow genetic merit on Fig. 1 shows the milk production profiles for the live weight and condition score at different stages of HG and MG cows during the first, second and third lactation when cows were in their first, second and lactations. Peak milk production was 28.1 and 23.9 third lactation. Cow genetic merit had no significant kg / day at week 8 of lactation, 34.9 and 30.6 kg / day effect on live weight at any stage during first, second at week 9 of lactation and 39.4 and 34.9 kg / day at or third lactation with the exception of the start of week 6 of lactation for the HG and MG cows during the second lactation when the HG cows had a the first, second and third lactations, respectively. significantly (P,0.05) higher live weight. The MG cows had significantly (P,0.001) higher condition 3.3. DM intake estimates score at all stages of lactation while as first, second and third lactation. Figs. 3 and 4 show the lactation Table 4 shows the effect of genetic merit on profiles for live weight and condition score averaged GDMI and TDMI for the intake estimates taken on over first, second and third lactation (26 weeks). The all cows during the grazing season as first, second average live weight change from weeks 1 to 4, 4 to 8 and third lactation. The average lactation stage when and 8 to 12 of lactation were 20.80 and 20.65, the intake estimates were obtained were 164, 161 20.33 and 20.26, and 0.06 and 0.06 for the HG and and 114 days into lactation in the first, second and MG cows, respectively, over the three lactations. third lactation, respectively. The individual TDMI However, none of the differences observed between estimates over the three lactations are shown in Fig. the two genotypes were significant. The HG cows 2. The HG cows had significantly (P,0.001) higher had significantly (P,0.05) greater condition score GDMI and TDMI when compared to the MG cows change averaged across the three lactations from in the first, second and third lactations (Table 4). The weeks 1 to 4 (20.14 vs. 20.09) and weeks 4 to 8
Table 4
The effect of cow genetic merit on intake (kg / cow / day) of grass dry matter (GDMI) and total dry matter (TDMI) over three lactations
Lactation no. Days in milk Intake Cow genetic merit Significance
Table 5
The effect of cow genetic merit on intake (kg / cow / day) of silage dry matter (SDMI), grass dry matter (GDMI) and total dry matter (TDMI)
Lactation no. Days in milk Intake Cow genetic merit Significance
a
HG MG S.E.D.
2 – SDMI 13.2 12.1 0.21 **
3 25 SDMI 10.3 10.1 0.40 NS
TDMI 18.1 18.0 0.40 NS
3 34 GDMI 17.2 15.7 0.62 *
TDMI 21.5 20.0 0.62 *
a
S.E.D., standard error of difference; NS, not significant (P,0.05); *P,0.05; **P,0.01.
Table 6
Live weight and condition score of high (HG) and medium (MG) genetic merit over three lactations (first, second and third)
First lactation Second lactation Third lactation (26 weeks) Significance
a
HG MG S.E.D. HG MG S.E.D. HG MG S.E.D. 1st 2nd 3rd
Live weight (kg)
Pre-calving 592 585 8.0 650 634 8.4 714 705 12.9 NS * NS
Week 1 522 518 8.9 572 563 8.1 616 611 11.0 NS NS NS
Week 8 491 490 7.6 536 538 8.5 591 589 10.0 NS NS NS
End of lactation 549 560 8.8 631 649 11.4 – – – NS NS –
Condition score
Pre-calving 2.79 3.25 0.069 3.04 3.38 0.067 3.09 3.63 0.086 *** *** ***
Week 8 2.35 2.77 0.066 2.44 2.92 0.069 2.42 3.19 0.102 *** *** ***
End of lactation 2.52 2.97 0.074 2.75 3.35 0.078 – – – *** *** –
a
S.E.D., standard error of difference; NS, not significant (P,0.05); *P,0.05; ***P,0.001.
Fig. 4. Effect of cow genetic merit (———, HG; - - -, MG) on condition score by week of lactation averaged over the three lactations.
(20.12 vs. 20.07) of lactation when compared to and Ireland (.0.85 genetic correlation) but a consid-the MG cows. The averaged live weight gain (kg / erable scaling effect between the two countries. This day) between first and second, and between second scaling effect indicated that grass-based feeding and third lactation was significantly (P,0.01) higher systems like those in Ireland reduce the ability of the (11.20 vs.10.91) for the HG cows when compared animal to exploit its full genetic advantage. In the
to the MG cows. present study there was no interaction between cow
genetic merit and feeding system for any of the performance traits measured (Buckley, 1999). The
4. Discussion difference in milk production observed between the
two genetic groups, averaged across first and second 4.1. Milk yield and composition lactation, was 931 kg. This is larger than the expected difference of 670 kg from the predicted Holmes (1988) reviewed the results of a series of difference (PD) information. This suggests that grazing studies undertaken in New Zealand with both present day high genetic merit cows can perform Jersey and Friesian cows. In all cases the high merit satisfactorily on grass-based systems when the ani-cows outperformed the low merit ani-cows in terms of mals are allowed adequate access to high quality milk production irrespective of the stocking rate. pasture.
Bryant (1984) concluded that where the objective is
high milk production per ha from grazed grass, top 4.2. DM intake priority should be given to improving the genetic
high genetic merit cows this upper limit can be influence on partial efficiency of ME use for milk increased. Averaged across the three lactations, at production (Blake and Custodio, 1984; Grainger et pasture the HG cows consumed on average 1.2 kg al., 1985b). Therefore most of the remaining extra DM / cow / day more than the MG cows. These results energy requirement for milk yield with HG cows has are higher than those reported previously (Grainger to come from body tissue mobilisation. The greater et al., 1985a; Belyea and Adams, 1990; Gordon et live weight and condition score change in early al., 1995). Total DM intake expressed in kg / kg live lactation (week 1 to 8) with the HG cows is similar weight was 0.033 and 0.030 for the HGI and MGI to that observed previously (Grainger et al., 1985a; cows, respectively. These values are similar to that Veerkamp et al., 1994; Gordon et al., 1995) indicat-reported by Veerkamp et al. (1994) for mature dairy ing that the HG cows were in a larger negative cows (selected line) in the first 182 days of lactation energy balance (Britt, 1992). Butler and Smith of 0.032 and 0.029 on high and low concentrate (1989) showed that greater negative energy balance diets, respectively. The increased area (5 to 6%) in early lactation is associated with reduced re-allocated to the HG with similar post-grazing sward productive performance. The large difference in surface heights is in line with the increased intake condition score between the two genetic groups at all achieved. This was also demonstrated by a large stages of lactation may be as a consequence of grazing experiment with Jersey cows of two genetic selection for higher milk yield and angularity in HG indexes at varying stocking rates in New Zealand cows. Veerkamp and Brotherstone (1997) observed (Bryant, 1983a, 1984, 1985). The higher SDMI similar characteristics in HG cows. The increased observed with the HG cows during the non-lactating live weight going from first to third lactation was period is similar to that observed previously (Bryant, similar for both genetic groups. However the
in-1983b). crease in body condition score was much greater,
While at pasture the difference in DM intake e.g. for the MG (10.42) compared to the HG between the genetic groups was 0.7, 1.4 and 1.6 kg (10.07) at week 8 of lactation. This suggests that DM / day in the first, second and third lactation, cows ‘seek’ to reach a certain condition-score in respectively. On average the DM intake estimates early-lactation, which is influenced by genotype were 4.2 kg higher in the second lactation compared (Veerkamp et al., 1994). This also supports the view to those observed in the first lactation at a similar of Emmans and Neilson (1984) that animals reduce stage in lactation. The DM intake estimates in the their feed intake (or increase production) when more present study indicate that peak DM intake under lipid is available for mobilization, rather than the grazing conditions are achieved later in lactation than view that animals mobilize lipid because they with indoor systems where it is estimated to occur at produce more milk than can be supported from around week 16 of lactation (Bauman and Currie, intake alone.
1980), (Fig. 2). The increased grass DM intake associated with HG cows requires a lower stocking rate during the grazing season to allow for a higher
daily grass allowance. 5. Conclusions
Dillon, P., Stakelum, G., 1989. Herbage and dosed alkanes as a
Acknowledgements
grass measurement technique for dairy cows. Irish J. Agric. Res. 28, 104, Abstract.
The authors wish to acknowledge the staff at Dillon, P., Crosse, S., Stakelum, G., Flynn, F., 1995. The effect of ‘Curtins’ farm for their co-operation and care and calving date and stocking rate on the performance of spring-management of the experimental animals. The tech- calving dairy cows. Grass Forage Sci. 50, 286–299. nical assistance of M. Kearney, J. O’Dywer, P. Emmans, G.C., Neilson, D.R., 1984. A sufficient description of
cows and its feed requirements to attain its potential. In: 35th Power, J.J. Cahill and J. Flynn, and the partial
Meeting of the EAAP, Den Haag. funding of this project by the Irish Dairy Farmers
Farrell, T., 1998. Models of the shape of lactation curves in Irish and EU structural funds is also acknowledged.
dairy herds. Dissertation submitted in partial fulfilment of the requirements of the Applied Mathematical Degree, Dublin City University.
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