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Feeding intensity of pregnant heifers
Effect of feeding intensity during gestation on performance and
plasma parameters of primiparous Ayrshire cows
a ,
*
b a¨
P. Mantysaari
, K.L. Ingvartsen , V. Toivonen
a
Agricultural Research Centre, Animal Production Research, FIN-31600 Jokioinen, Finland b
Danish Institute of Agricultural Sciences, Department of Animal Health and Welfare, Research Centre Foulum, P.O. Box 50,
DK-8830 Tjele, Denmark
Received 3 September 1998; received in revised form 22 February 1999; accepted 15 March 1999
Abstract
The effect of different feeding intensity at two stages of gestation on performance of primiparous cows was studied in 40 pregnant Ayrshire cows. The feeding intensity was either medium (M) or high (H) in period 1 (2–6 months of pregnancy) or period 2 (7–9 months of pregnancy) resulting in treatments MM, MH, HM and HH. Before pregnancy all heifers were reared to gain 650 g / day. In period 1, heifers on H feeding intensity, grew significantly faster than heifers on M (844 vs. 638 g / day; SEM518.9). Daily gains in period 2 were affected by feeding intensity in period 1 and were 710, 1042, 636 and 874 g on MM, MH, HM, and HH diets, respectively. The body weights at calving were 462, 498, 480 and 499 kg on MM, MH, HM and HH diet, respectively. Feeding intensity in period 1 had no effect on milk production, but H plane of nutrition in period 2 increased milk yield by approximately 11% (22.6 vs. 20.3 kg / day, P,0.004). Medium feeding intensity in period 1 increased postpartum DMI, and decreased postpartum mobilization of body reserves. Mobilization was positively
correlated with BCS at calving (r50.48; P,0.003) and with plasma free fatty acid (r50.73; P,0.0001) and
b-hydroxybutyrate concentrations (r50.69; P,0.0001). Prepartum treatments had no effect on postpartum plasma growth hormone (GH) or prolactin concentration, but high feeding intensity in period 2 decreased insulin (INS) concentration postpartum. No relationships were found across treatments between milk yield and prepartum plasma hormone con-centrations, but a positive correlation was found between milk yield and postpartum GH and GH / INS. The results show that high compared with medium feeding intensity during the first two trimesters of gestation does not improve milk production of primiparous cows. Instead, during the last trimester a high feeding intensity is required for maximum milk yield. 1999 Elsevier Science B.V. All rights reserved.
Keywords: Feeding during gestation; Feeding intensity; Milk yield; Plasma parameters; Primiparous cows
1. Introduction
Feeding intensity during gestation can influence
*Corresponding author. Tel.: 1358-3-41881; fax.: 1
358-3-milk producing ability of primiparous cows by
4188-3661.
¨
E-mail address: [email protected] (P. Mantysaari) affecting calving body weight (BW), mobilizable
body reserves (MBR), and mammary growth and The purpose of the present experiment was to
development. Many studies have shown that the first study the effect of high prepartum feeding intensity
lactation milk yield correlates positively with BW at at different stages of pregnancy on milk production,
calving (Clark and Touchberry, 1962; Ingvartsen et feed intake and plasma hormone concentrations and
al., 1988; Foldager and Sejrsen, 1991). However, a metabolites of primiparous Ayrshire cows.
high plane of nutrition during gestation has often failed to increase milk production of primiparous
cows (Ducker et al., 1985; Valentine et al., 1987; 2. Material and methods
Lacasse et al., 1993; Grummer et al., 1995;
Ingvar-tsen et al., 1995a). The degree and duration of high 2.1. Animals and diets
feeding level and also the plane of nutrition before
gestation are likely to be important for these results. Forty pregnant Finnish Ayrshire heifers were
Foldager and Sejrsen (1991) reported an increase in blocked by due date (three blocks) and assigned
mammary development and milk production when randomly to one of four treatments on their fourth
prepartum (325 kg BW to calving) daily gain week of gestation. The gestation was divided into
increased from 400 to 600 g. A further increase in two periods: months 2–6 (period 1) and months 7–9
daily gain (800 g / day) did not improve milk pro- of pregnancy (period 2; the last trimester). During
duction further. In other studies, a high feeding period 1, one half of the heifers had the medium (M)
intensity during the last 6, 12 or 24 weeks before and the other half high (H) plane of nutrition. In
calving had no effect on milk yield (Foldager and period 2, half of the heifers on both planes of
Ingvartsen, 1995). A high feeding intensity for 24 nutrition were changed to the other plane of
nutri-weeks was, however, associated with decreased tion. Thus, the treatments were MM, MH, HM and
postpartum feed intake which is in accordance with HH.
Grummer et al. (1995) who also found negative Before breeding all heifers were treated the same
effect of high prepartum feeding intensity on dry and reared to gain 650 g / day. During gestation the
matter intake (DMI) with no change in milk pro- heifers were fed grass silage, barley, and mineral and
duction. vitamin supplements to meet the requirements for
Stair-step feeding (high feeding intensity follow- 650 and 850 g daily gain on M and H plane of
ing lower) of pregnant heifers has been reported to nutrition, respectively. The amount of barley varied
increase milk yield postpartum (Park et al., 1987, according to weight from 0.5–1.00 kg / day on M and
1989; Choi et al., 1997). Furthermore, stair-step from 1.75 to 2.25 kg / day on H plane of nutrition.
feeding increased the differentiation and functional All heifers received the same concentrate mix for the
activity of the mammary glands (Park et al., 1989; last 2 weeks before due date. The concentrate mix
Choi et al., 1997) which, at least in part, may explain which included 318 g / kg barley, 318 g / kg oats, 180
differences in milk yield. A possible explanation for g / kg rapeseed meal, 150 g / kg molassed sugar beet
enhanced mammary differentiation and milk pro- pulp, and 34 g / kg minerals and vitamins was given
duction measured in the compensatory growth pat- in an increasing amount and reached 5 kg / day at
tern associated with stair-step rearing are the changes parturition. After parturition the amount of
concen-in hormone secretion and enzymatic activities (Park trate mix was increased to 7.5 kg / day over a period
et al., 1988, 1989). Furthermore, Stelwagen et al. of 1 week and was kept constant until 160 days of
(1992) showed that bGH injection during the last lactation. From 2 weeks before parturition and for
trimester increases the milk production. This is the rest of the experimental period postpartum
supposed to be due to an increase in mammary heifers were offered grass silage ad libitum.
parenchymal cell number (Stelwagen et al., 1992).
However, the effect of changing feeding intensity 2.2. Measurements and sampling
during gestation in heifers on plasma hormone
concentrations and subsequent milk yield of During periods 1 and 2 live weight, heart girth,
primiparous cows has not been thoroughly investi- wither height, body length (from the point of the
condition score (BCS; from 15skinny to 55very analysed with KONE Specific autoanalyser
accord-fat; Lowman et al., 1976) of the heifers were ing to Hansen and Freier (1978).
recorded every fourth week. The calving BW was Hormones were analysed with double antibody
measured on calving day or the day after. BW of radioimmunoassays. For the assays of GH and PRL
calves were measured on the day of birth. During bovine GH antigen (AFP11182B) and bovine PRL
lactation cows were weighed once a week and BCS antigen (AFP4835B) were separately iodinated with
were recorded at the end of the experiment (day 160 the iodogen method (Salacinsku et al., 1981). First
of lactation). antibodies used were NIDDK-anti-oGH-2
Individual feed intakes were recorded daily (AFPC0123080) and NIDDK-anti-bPRL-2
through out gestation and lactation periods. Daily (AFP753180). Second antibody in both assays was
samples of each feed were composited to give a anti-rabbit IgG (Sigma R-0881). As standards
4-week sample for proximate and NDF analysis. The USDA-bGH-B-1 5200) and bPRL, BIO
(AFP-chemical composition of feeds is given in Table 1. 7170E) were used. INS was measured with
Milk yields were recorded daily and milk protein, Phaseseph Insulin RIA (Pharmacia Diagnostics,
fat, and lactose were analyzed once a week. Uppsala, Sweden). The recommended procedures
Blood samples were taken from each animal from accompanying the above mentioned hormones,
anti-the coccygeal vein at 35, 28, 21, 16, 12, 8 and 4 days bodies and the insulin kit were followed.
before due date and 0, 1, 3, 7, 14, 21, 28, 35, 42, 56, Inter-assay variation for hormone measurements
84 and 112 days postpartum. Blood was collected in was included in the block effect and, therefore, does
heparinized tubes and stored on ice until centrifuged not influence the comparisons. Intra-assay variation
at 248C for 15 min at 20003g. Blood for b- for GH, PRL, and INS were 4.4, 5.6 and 5.8%,
hydroxybutyrate (BHBA) analysis was precipitated respectively. Intra- and inter-assay variation were 6.0
with HClO4 and centrifuged. Plasma and HClO4 and 9.1% for free fatty acids (FFA), 2.3 and 3.8% for
precipitated blood samples were frozen and stored at BHBA and 2.0 and 3.9% for glucose, respectively.
2208C for later analysis of glucose, free fatty acids
(FFA), growth hormone (GH), prolactin (PRL), and 2.3. Calculations and statistical analyses
insulin (INS). Glucose was analysed using
Peridoch-rom GOD-PAP/ glucose kit (Boehringer Mannheim, Metabolizable energy (ME) values of the feeds
Germany) and FFA using an analytical kit (Waco were calculated according to MAFF (MAFF, 1975).
Pure Chemical Industries) which was optimised to The digestibility coefficients of the feeds were from
TM
conditions for an Opera autoanalyser. BHBA was the feed tables by Tuori et al. (1996). Every 4-week
Table 1
Chemical composition of the feeds fed during gestation and lactation
Gestation Lactation
a
Grass silage Barley Grass silage Concentrate
n 18 12 22 10
A mix of barley (318 g / kg, oats (318 g / kg), rapeseed meal (180 g / kg), molassed sugar beet pulp (150 g / kg) and minerals and vitamins (34 g / kg).
b
weights before parturition and 1-week weights after yijklmn5m 1P1i1P2j1(P13P )2 ij1Bk1Anrl
parturition were used to compute growth curves
1Sijklm1Tn1(T3P )1 ni1(T3P )2 nj
using a cubic function on time for each animal. From
1(T3P 3P ) 1e ,
the individual growth curves, initial and final weights 1 2 nij ijklmn
in periods 1, 2, and lactation were predicted and used
where P1 , P2 , Si j ijklm and T are as described in then
in the statistical analyses. Energy value of weight
previous models, Anr is the fixed effect of assayl
gain during pregnancy (EV , MJ / kg) was calculatedg
number. Anrl was included in the analyses of
from the ME above maintenance and activity using
hormones. For plasma data no interactions were
the efficiency of utilization of ME for growth (kf5
found. Therefore, only the main effects (P1 , P2 andi j
0.78q10.006). Requirement of ME for maintenance
T ) were tested.n
and activity was calculated using equations proposed
The body weight change during lactation as well by AFRC (1993). One heifer on HM and one on HH
as energy and protein efficiency were analyzed from treatment gave birth to a stillborn about 2.5 months
the combined data of each cow. The following model before due date. Data from these two heifers were
was used: excluded. Feed intake, growth, and body
measure-y 5m 1P1 1P2 1(P13P2) 1b BWI
ment data of the heifers during gestation were ijk i j ij BWI k
analyzed using the GLM procedure (SAS , 1987). 1e ,
ijk
The full model was:
where P1 and P2 are as described in the previousi j
yijk5m 1P1i1P2j1(P13P2)ij1Bk1e ,ijk
model, bBWI is the linear effect of the pedigree index
for BW (BWI ). The BWI was included only in the
where P1 is the fixed effect of plane of nutrition ini k k
analysis of BW data. The relationship between
period 1; P2 the fixed effect of plane of nutrition inj
production measurements and circulating mean
plas-period 2; B is the fixed effect of block; terms P2k j
ma metabolite concentrations were described by
and (P1i3P2 ) were not included in the analyses ofj
Pearsons correlations calculated across individuals data from period 1. In period 2 data no interaction
across treatments. between periods 1 and 2 was found, therefore, only
the main effects (P1 and P2 ) were considered.i j
Production and feed intake data during lactation
3. Results and discussion
and also plasma parameters were analyzed as re-peated measurements using the MIXED procedure
3.1. Growth during pregnancy
(SAS , 1992). The variance component estimation method was REML and the type of covariance
The effect of plane of nutrition on growth and feed matrix was first-order autoregressive [AR(1)]. The
intake of heifers during pregnancy is presented in model used for production and feed intake data was:
Table 2. Average initial body weight of heifers was
yijklmn5m 1P1i1P2j1(P13P )2 ij1b II k 356 kg. In period 1, the daily gain were 638 and 844
1b AA l1Sijklm1Tn1(T3P )1 ni g for M and H, respectively. The M plane of nutrition in period 1 led to significantly higher
1(T3P )2 nj1(T3P13P )2 nij1eijklmn,
growth of the heifers in period 2. Thus, in period 2
where P1 and P2 are as described in the previousi j the daily gains of heifers were 710, 1042, 636 and
model, b is the linear effect of pedigree index (I ) ofI k 874 g on MM, MH, HM and HH treatments,
the heifers appropriate for milk, fat%, protein%, or respectively. Heifers on MH and HH treatments had
protein yield, b is the linear effect of the age (A ) atA l almost equal BW at calving due to higher growth of
parturition, Sijklm is the random effect of the heifer, the heifers in period 2 on treatment MH compared
and T the week of lactation. Prior to analyses, GH,n with heifers on treatment HH. The plane of nutrition
PRL, and INS were transformed into natural in period 1 had no effect on final BW. Because of the
logarithms to improve normality. The model used for compensatory growth in period 2, feed conversion
Table 2
Body weight, growth and feed intake of heifers during gestation (LS-means)
a b
Plane of nutrition SEM Effect (P)
Period 1: M H Period 1 Period 2
Period 2: MM MH HM HH
Body weight (kg)
Initial 361 351 4.4 –
After 1st period 450 470 5.5 0.02 –
After 2nd period 503 545 522 544 8.2 0.0005
Daily gain (g / day)
Period 1 638 844 18.9 0.001 –
Period 2 710 1042 636 874 45.9 0.01 0.0001
Feed intake DM (kg / day)
Period 1 5.48 6.64 0.058 0.0001 –
Period 2 5.60 6.92 5.87 6.99 0.024 0.08 0.0001
ME (MJ / day)
Period 1 60.8 76.0 0.67 0.0001 –
Period 2 62.1 79.1 65.2 80.0 1.04 0.06 0.0001
CP (kg / day)
Period 1 0.75 0.91 0.008 0.0001 –
Period 2 0.76 0.93 0.80 0.94 0.013 0.09 0.0001
Feed conversion ME (MJ) / gain (kg)
Period 1 96.8 90.9 2.58 –
Period 2 89.3 79.0 107.7 99.4 7.32 0.02
Energy value of gain c
EVg (MJ / kg)
Period 1 22.0 25.7 0.66 0.0003 –
Period 2 18.3 20.9 22.4 26.2 1.87 0.02 0.10
a
Plane of nutrition during gestation. M, medium feeding intensity; H, high feeding intensity; period 1, the first and second trimesters; period 2, the last trimester; n in period 1 is 20 animals / treatment while it is 10 animals / treatment in period 2.
b
P,0.1 is shown. c
EVg5[(ME intake2ME maintenance2ME activity)3k ] / live weight gain. ME maintenance and activity calculated according to thef AFRC (1993). kf50.78q10.006.
fed M diet in period 1. The compensatory growth of partum. The H feeding intensity in period 1
in-pregnant heifers is reported also by Lacasse et al. creased heart girth, hip width and BCS of the heifers
(1993) when high feeding level followed moderate at the end of period 1, but only the effect for BCS
feeding level. In their study the experimental period was significant. The final heart girth, hip width and
was divided into two parts, from 12 months of age to BCS of the heifers were affected by the plane of
3 months of gestation and from 3 months of gesta- nutrition in period 1 and 2 being the highest on HH
tion to 2 weeks prepartum. and the lowest on MM treatment (Table 3). These
The plane of nutrition prepartum had no effect on results indicate that a high compared to moderate
wither height or body length of the heifers at plane of nutrition during pregnancy had no effect on
parturition (Table 3). In agreement, Lacasse et al. body size (wither height, body length) of primiparous
(1993) found no difference in wither height of the cows. However, the high plane of nutrition especially
Table 3
Body measurements of heifers during gestation (LS-means)
a b
Plane of nutrition SEM Effect (P)
Period 1: M H Period 1 Period 2
Period 2: MM MH HM HH
Heart girth (cm)
Initial 166 165 1.0
After 1st period 178 181 1.2
After 2nd period 177 183 183 185 1.5 0.04 0.05
Wither height (cm)
Initial 121 120 0.8
After 1st period 124 123 0.6
After 2nd period 125 127 126 125 0.9
Body length (cm)
Initial 121 120 0.9
After 1st period 135 134 1.1
After 2nd period 142 143 141 141 1.0
Hip width (cm)
Initial 43.0 43.4 0.37
After 1st period 46.9 47.7 0.43
After 2nd period 49.0 50.2 50.7 51.4 0.52 0.009 0.08
c Body condition score
Initial 3.03 3.09 0.066
After 1st period 3.11 3.28 0.034 0.001
After 2nd period 3.11 3.27 3.23 3.47 0.047 0.001 0.0002
a
Plane of nutrition during gestation. M, medium feeding intensity; H, high feeding intensity; period 1, the first and second trimesters; period 2, the last trimester; n in period 1 is 20 animals / treatment while it is 10 animals / treatment in period 2.
b
P,0.1 is shown. c
Body condition score measured from a scale 1–5 with interval 0.25 as described by Lowman et al. (1976).
the amount of body fat reserves as indicated by the daily gain to 800 g. In agreement with Foldager and
calculated energy value of the weight gain (Table 2). Sejrsen (1991), Ducker et al. (1985), Lacasse et al.
(1993), and Foldager and Ingvartsen (1995) found
3.2. Milk production and composition no improvement in milk production when heifers
gained more than 600–700 g a day prepartum.
A high plane of nutrition during the first two Valentine et al. (1987) observed no difference in
trimesters of pregnancy did not affect milk pro- milk production in primiparous cows gaining 220,
duction. During the last trimester a high feeding 590, or 1090 g / day during the last 4.5 months of
intensity increased (P,0.004) milk yield and ECM gestation. Harrison et al. (1983), on the other hand,
yield by approximately 11% (Table 4, Fig. 1). recorded an increased mammary development when
Therefore, the results indicate that a high feeding the daily gain of heifers during pregnancy increased
intensity at late pregnancy is required to ensure the from 680 to 840 g. A comparison of the above
maximum milk production of primiparous cows. studies is difficult, however, since the breed of the
Foldager and Sejrsen (1991) reported an enhanced heifers and the duration of treatment periods vary.
mammary development and increased milk product- Furthermore, rearing during the prepubertal period
ion when prepartum daily gain increased from 400 to varies among studies and sometimes also between
Table 4
Production and feed intake of heifers during the 160-days lactation period (LS-means)
a b
Variable Plane of nutrition SEM Effect (P)
c
Milk protein (g / kg) 3.47 3.45 3.54 3.35 0.065 0.0001
Milk lactose (g / kg) 4.99 5.13 5.06 5.10 0.044 0.05
Feed intake
Milk protein / CPI 0.31 0.33 0.32 0.33 0.007 0.007 –
a
Plane of nutrition during gestation. M, medium feeding intensity; H, high feeding intensity; P1 (period 1), the first and second trimesters; P2 (period 2), the last trimester.
b
because prepubertal plane of nutrition can affect milk yield (Little and Kay, 1979; Ingvartsen et al., 1988; Foldager and Sejrsen, 1991). In the present study, the heifers were reared equally from birth to the begin-ning of the experiment to diminish the effect of prepubertal management.
The prepartum plane of nutrition had no effect on mean milk fat or protein content during the experi-ment as such (Table 4). However, there was a
significant interaction of treatment3time of lactation
for milk fat and protein content. During the first weeks of lactation, the milk fat content on HH treatment was higher than on other treatments. This was assumed to be due to a larger body fat mobiliza-tion and, therefore, higher plasma FFA concentramobiliza-tion of cows on HH treatment than on other treatments prepartum. In agreement with our results, Grummer et al. (1995) and Foot et al. (1963) reported a
Fig. 1. Daily milk yield of primiparous cows fed a different significantly higher milk fat percentage during the
feeding intensity during pregnancy (medium plane of nutrition first weeks of lactation for primiparous cows fed a during gestation (1), high plane of nutrition during gestation (j), high plane of nutrition compared with a standard medium plane of nutrition in period 1 (first two trimesters of
plane of nutrition prepartum.
gestation) and high plane of nutrition in period 2 (last trimester of
The prepartum plane of feeding does not usually
gestation) (m), or high plane of nutrition in period 1 and medium
(Lacasse et al., 1993; Foldager and Ingvartsen, 1995; Grummer et al., 1995). However, in the present study, ignoring the first week of lactation, we
observed a higher (P,0.04) protein content for
heifers fed M plane of nutrition in period 2. The reason for this is unclear, but might be related to the negative correlation between milk production and milk protein content.
3.3. Calving body weight, mobilization of body fat
and feed intake
Feeding intensity in period 1 had no significant effect on BW at calving whereas a high plane of nutrition in period 2 increased it (Table 5). Milk
Fig. 2. Postpartum body weight change of primiparous cows fed
yield was positively correlated with BW at calving at different feeding intensity during pregnancy (medium plane of
(r50.33; P,0.05) as has also been seen in many nutrition during gestation (1), high plane of nutrition during
previous studies (Ingvartsen et al., 1988; Foldager gestation (j), medium plane of nutrition in period 1 (first two
trimesters of gestation) and high plane of nutrition in period 2 (last
and Sejrsen, 1991; Hoffman and Funk, 1992). The
trimester of gestation) (m), or high plane of nutrition in period 1
cows on MH and HH feeding intensity prepartum
and medium plane of nutrition in period 2 (*)).
had the same (498 and 499 kg) calving BW. How-ever, the heifers on MH treatment were probably
closer to their mature body size at calving than the MH treatment were 28 kg heavier than cows on HH
heifers on HH treatment even if no significant treatment with no difference in BCS.
differences in wither height or body length were The MBR was positively correlated with BCS at
measured. The background for this assumption was calving (r50.48; P,0.003). The cows on HH
the expected difference in body content of the cows treatment prepartum mobilized more body weight
as indicated by the differences in energy value of during lactation than others and cows on MM
weight gain (Table 2), BCS at calving (Table 3) and treatment during pregnancy did not lose any body
mobilized body reserves (MBR) during lactation weight. Instead, their demand for energy for growth
(Table 5, Fig. 2). On day 160 of lactation cows on was high already from the beginning of lactation
Table 5
Body weight change of the cows during lactation period and body weight of their calves at birth (LS-means)
a b
Variable Plane of nutrition SEM Effect (P)
MM MH HM HH P1 P2
BW at calving (kg) 462 498 480 499 8.1 0.003
BW on day 160 of lactation 513 520 505 492 12.1
Aver. gain (days 0–160)
(kg / day) 0.31 0.12 0.15 20.04 0.050 0.003 0.0008
Total mobilization of BW
in lactation (kg) 0.0 11.6 10.1 28.4 3.54 0.0006 0.0002
c
Final BCS 3.20 2.92 3.03 2.83 0.124 0.06
a
Plane of nutrition during gestation. M, medium feeding intensity; H, high feeding intensity. P1 (period 1), the first and second trimesters; P2 (period 2), the last trimester.
b
P,0.1 is shown. c
for total DMI was measured (Table 4) and no correlation between BCS at calving and DMI
post-partum was measured (r5 20.005; P,0.97).
How-ever, the HH cows had lower concentrate intake during the first 5 weeks of lactation (5.39 vs. 6.11 kg
DM / day; P,0.03) than the cows on other
treat-ments.
3.4. Plasma concentration of hormones and
metabolites
Plasma glucose and BHBA concentrations during lactation and plasma FFA and hormone concen-trations pre- and postpartum are given in Figs. 4 and 5. The feeding intensity prepartum had no significant
Fig. 3. Postpartum daily dry matter intake of primiparous cows
effect on plasma FFA concentrations from day 35
fed at different feeding intensity during pregnancy (medium plane
prepartum to calving. A high feeding intensity in
of nutrition during gestation (1), high plane of nutrition during
gestation (j), medium plane of nutrition in period 1 (first two periods 1 and 2 increased the plasma concentration
trimesters of gestation) and high plane of nutrition in period 2 (last of BHBA (period 1, P,0.003; period 2, P,0.01) trimester of gestation) (m), or high plane of nutrition in period 1
and FFA (period 1, P,0.0001; period 2, P,0.02)
and medium plane of nutrition in period 2 (*)).
during early lactation. The effect of period 1 was higher than the effect of period 2. Thus, the con-centrations of BHBA and FFA were directly
corre-(Figs. 2 and 3). Thus, the low milk yields of MM lated with the duration of high feeding intensity
cows are, at least in part, explained by the lack of during gestation. The correlations of BHBA and FFA
body energy reserves to support the production in with BCS (r50.41 and r50.62; P,0.02) and MBR
early lactation. (r50.69 and r50.73; P,0.0001) were positive.
The heifers on medium feeding intensity during Thus, especially FFA, but also BHBA plasma
con-period 1 had a higher postpartum DMI. On both centrations were indicating the degree of utilization
treatments MM and MH the initial DMI was equal. of body fat reserves. The prepartum treatments had
After week 8 of lactation the increase in DMI of the no significant effects on postpartum plasma glucose
cows fed MM diet prepartum decrease compared to which is in accordance with Ingvartsen et al.
cows on MH diet (Fig. 3). This is mostly explained (1995b).
by two cases of ketosis on MM treatment. The The feeding intensity during gestation had no
feeding intensity in period 2 had no significant effect effect on the prepartum plasma PRL concentration or
on postpartum DMI (Table 4). This is in agreement periparturient surge of PRL (P,0.09). Lacasse et al.
with Foldager and Ingvartsen (1995) who measured (1994) measured an increased prepartum PRL
con-no change in postpartum DMI due to increase in centration with the H plane of nutrition. They
feeding intensity in weeks 6 or 12 prepartum. But speculated that the increase in PRL was associated
when the feeding intensity was high throughout the with an increased lipogenesis in heifers. In the
last 24 weeks before calving, DMI decreased present study prepartum PRL was not correlated with
dramatically. The heifers with high feeding intensity BCS at calving (r50.02, P,0.90) or MBR during
throughout the last 24 weeks prepartum were fat at lactation (r50.13, P,0.44). A high feeding
intensi-calving. Based on their review, Ingvartsen et al. ty during the last trimester of gestation increased
(1995a) suggested that the high prepartum feeding significantly (P,0.0001) the prepartum plasma INS
and high BCS at calving will cause lower initial and concentration, but decreased (P,0.006) it during
delayed maximum feed intake. In our study no lactation. The postpartum INS was highly correlated
Fig. 4. Plasma FFA (a), BHBA (b) and glucose (c) concentration Fig. 5. Plasma growth hormone (a), prolactin (b) and insulin (c) of primiparous cows fed at different feeding intensity during concentrations of primiparous cows fed at different intensity pregnancy (medium plane of nutrition during gestation (1), high during pregnancy (medium plane of nutrition during gestation plane of nutrition during gestation (j), medium plane of nutrition (1), high plane of nutrition during gestation (j), medium plane in period 1 (first two trimesters of gestation) and high plane of of nutrition in period 1 (first two trimesters of gestation) and high nutrition in period 2 (last trimester of gestation) (m), or high plane plane of nutrition in period 2 (last trimester of gestation) (m), or of nutrition in period 1 and medium plane of nutrition in period 2 high plane of nutrition in period 1 and medium plane of nutrition
P,0.0006), BHBA (r5 20.44, P,0.007) and glu- between milk yield and postpartum plasma
con-cose (r50.56, P,0.0004). In agreement with Lacas- centration of GH, INS and GH / INS were 0.35 (P,
se et al. (1994) the prepartum plasma concentration 0.04), 20.51 (P,0.002), and 0.51 (P,0.002),
of GH was decreased by H plane of nutrition (P, respectively. This indicates the galactopoietic effect
0.0001). In contrast to our findings, Ingvartsen et al. of GH and the lipogenic effect of INS. The
post-(1995b) measured no difference in the plasma GH partum ratio of GH to INS was significantly
in-concentration between heifers fed a high or a creased (P,0.05) by a high feeding intensity in
medium plane of nutrition during late pregnancy. In period 2, which partly explains the increased
parti-our study, the prepartum treatments had no effect on tioning of nutrients towards the mammary gland in
postpartum plasma GH concentrations which is in treatments MH and HH.
agreement with findings by Lacasse et al. (1994) and Ingvartsen et al. (1995b).
The GH, INS and PRL have a mammogenic effect 4. Conclusions
during gestation (Forsyth, 1971; Akers et al., 1981;
Stelwagen et al., 1993). Stelwagen et al. (1992) The feeding intensity from 2 to 6 months of
measured an increased milk production with an gestation (period 1) had no effect on milk production
injection of bGH during the last trimester of gesta- ability of primiparous cows, but a high feeding
tion. Based on their study with ewes, they proposed intensity during the last trimester (period 2)
in-that improved milk yields with prepartum bGH creased milk yields. The BW change during lactation
injections are due to an increased number of mam- differed markedly between treatments. The
mobiliza-mary cells (Stelwagen et al., 1993). In the present tion of body reserves correlated with BCS at calving,
study, the prepartum GH concentration was not and was the highest on the HH treatment. A high
related to milk yield (Table 6). Furthermore, neither feeding intensity in period 2 increased the INS and
the prepartum INS nor PRL concentration was decreased the GH prepartum plasma concentration.
correlated with milk production (Table 6). Therefore, The postpartum plasma GH concentration was not
it seems unlikely that the increased milk with high affected by the prepartum feeding intensity, but a
feeding intensity in period 2 should be related to high feeding intensity in period 2 decreased the
changes in prepartum mammary development due to postpartum INS concentration and, consequently,
endocrine (GH, INS, PRL) factors. More likely, the increased the GH / INS level. No significant
correla-higher production was due to differences in physio- tions between prepartum hormone concentrations and
logical status (calving BW, body reserves) of the milk yield were found. The increased milk yields of
heifers at calving. the cows fed a high feeding intensity during the last
The correlations between postpartum hormone trimester of gestation are believed primarily to be
concentrations and milk production calculated across due to the differences in physiological status (calving
treatments are listed in Table 6. The postpartum PRL BW, body fat reserves) of the heifers at calving. The
concentration was not related to milk production as postpartum plasma levels of the GH and the GH / INS
was shown by Lacasse et al. (1994). The correlations were positively correlated with the milk yield. It can
Table 6
Correlations between plasma growth hormone (GH), insulin (INS) and prolactin (PRL) concentrations pre- and postpartum and milk production
Hormone Prepartum hormone concentration3 Postpartum hormone concentration3
Foldager, J., Sejrsen, K., 1991. In: Rearing Intensity in Dairy
be concluded that a high feeding intensity during the
Heifers and the Effect On Subsequent Milk Production,
Nation-first 6 months of gestation does not improve the
al Institute of Animal Science, Foulum, Denmark, Report 693.
performance of primiparous Ayrshire cows reared to Foot, A.S., Line, C., Rowland, S.J., 1963. The effect of
pre-gain 650 g / day prior to breeding. Instead, during the partum feeding of heifers on milk composition. J. Dairy Res.
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last trimester of gestation a high plane of nutrition is
Forsyth, I.A., 1971. Reviews of the progress of dairy science.
required for optimum performance.
Section A. Physiology. Organ culture techniques and the study of hormone effects on the mammary gland. J. Dairy Res. 3, 419–445.
Grummer, R.R., Hoffman, P.C., Luck, M.L., Bertics, S.J., 1995.
Acknowledgements
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GH and PRL antigens, standards and antibodies Hansen, J.L., Freier, E.F., 1978. Direct assays of lactate, pyruvate,
were kindly donated by USDA Animal Hormone b-hydroxybutyrate, and acetoacetate with a centrifugal
ana-lyzer. Clin. Chem. 24 (3), 475–479.
Program, the National Hormone and Pituitary
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gram, the National Institute of Diabetes and
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tive and Kidney Diseases, the National Institute of rates of live weight gain. J. Dairy Res. 50, 405–412.
Child Health and Human Development, US Depart- Hoffman, P.C., Funk, D.A., 1992. Applied dynamics of dairy
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Harbor-UCLA Medical Center. Dr J. Proudman
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(USDA) and Dr A.F. Parlow are acknowledged for th
In: The 46 Eur. Assoc. Anim. Prod. Annual Meeting, Prague,
instructions concerning GH and PRL radioim- Prepartum Feeding of Dairy Cattle: A Review of the Effect On
munoassays. This study is financially supported by Peripartum Metabolism, Feed Intake, Production, and Health.
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