Feed conversion efficiency, daily pasture intake, and

New Zealand Journal of Agricultural Research

ISSN: 0028-8233 (Print) 1175-8775 (Online) Journal homepage: http://www.tandfonline.com/loi/tnza20

Feed conversion efficiency, daily pasture intake, and milk production of primiparous Friesian and Jersey cows calved at two different liveweights T. R. Mackle , C. R. Parr , G. K. Stakelum , A. M. Bryant & K. L. MacMillan To cite this article: T. R. Mackle , C. R. Parr , G. K. Stakelum , A. M. Bryant & K. L. MacMillan (1996) Feed conversion efficiency, daily pasture intake, and milk production of primiparous Friesian and Jersey cows calved at two different liveweights, New Zealand Journal of Agricultural Research, 39:3, 357-370, DOI: 10.1080/00288233.1996.9513195 To link to this article: http://dx.doi.org/10.1080/00288233.1996.9513195

Published online: 17 Mar 2010.

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New Zealand Journal of Agricultural Research, 1996, Vol. 39: 357-370 0028-8233/96/3903-0357 $2.50/0 © The Royal Society of New Zealand 1996

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Feed conversion efficiency, daily pasture intake, and milk production of primiparous Friesian and Jersey cows calved at two different liveweights T. R. MACKLE1 C. R. PARR1 G. K. STAKELUM2 A. M. BRYANT1 K. L. MacMILLAN1 1 Dairying Research Corporation Private Bag 3123 Hamilton, New Zealand 2

Teagasc Agricultural and Food Development Authority Moorepark Research Centre Fermoy Co. Cork, Ireland

Abstract Pasture dry matter intake (DMI), milk yield and composition, and calculated feed conversion efficiencies (FCE), were monitored throughout lactation for primiparous Friesian (n = 16; F) and Jersey (n = 16; J) cows calved at either high (H) or low (L) calving liveweights (CLW). Half of the cows within each breed were differentially fed (H versus L) during the 8 weeks before expected calving date to produce CLWs of 404 (FH), 354 (FL), 334 (JH), and 277 (JL) ± 14 (SED) kg. Animals were fully fed on pasture as one group after calving throughout lactation. J cows were more efficient than F cows in converting DM into solids-corrected milk (SCM) (1.63 versus 1.49 ± 0.07 kg/kg DMI), milksolids (MS) (129 versus 115 ± 5 g/kg DMI), milk fat (79 versus 67 ± 3.8 g/ kg DMI), and metabolisable energy intake (MEI) into milk energy (43 versus 37 ± 1.8%). Average DMI measured during six periods across lactation and once after the completion of lactation, were higher for F than J cows (10.5 versus 8.6 ± 0.2 kg/ cow per day) but CLW had no effect on average DMI. CLW did however, affect DMI at 215 days A95076 Received 21 December 1995; accepted 12 July 1996

since calving (DSC) when LCLW cows consumed more DM (FH, 11.3; FL, 12.0; JH, 9.4; JL, 10.2 (0.4 kg DM/cow per day). Liveweight-corrected DMI were slightly greater for J cows (2.66 versus 2.55 ± 0.05 kg/cow per day per 100 kg LW). The HCLW cows lost LW while LCLW cows gained LW until 56 DSC (FH, -8.9; FL, 33.4; JH, -25.9; JL, 10.4 ( 8.5 kg LW/cow), with JH cows losing more than FH (P < 0.01). The LCLW cows produced less (P < 0.01) milk, SCM, protein, milk fat, and lactose over the first 30-56 DSC. Thereafter, differences between CLW groups were not significant. Average daily milk yield across the whole lactation was affected by CLW (12.2 versus 11.0 (0.6 kg/cow per day; HCLW versus LCLW). LCLW cows had higher concentrations of milk protein (38.5 versus 36.1 ± 0.8 g/1000 g) and milk fat (57.1 versus 54.1 ± 1.5 g/1000 g). It was concluded that J cows were more efficient converters of pasture DM into MS, primarily because of a greater efficiency in milk fat production. CLW reduced milk production during the early part of lactation but did not affect DMI until mid lactation. Keywords Friesian; Jersey; cows; alkanes; dry matter intake; milk; protein; milk fat; feed conversion efficiency INTRODUCTION Limited data are available on the comparative feed conversion efficiency of lactating Friesian (F) and Jersey (J) cows. No published data describe individual dry matter intakes (DMI), feed conversion efficiency (FCE) parameters, or milk production and composition of primiparous F and J cows at any stage of lactation, under pasture grazing conditions in New Zealand. The studies of Bryant et al. (1985), Gibson (1986), and L'Huillier et al. (1988) showed that F cows produced more milk and milksolids per cow than J cows. The data on comparative FCE of these

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New Zealand Journal of Agricultural Research, 1996, Vol. 39

two breeds in these studies were equivocal. For example, Bryant et al. ( 1985) concluded that higher per cow production from F cows reflected a higher FCE as opposed to higher intake. Gibson (1986) found that F cows were more efficient at producing liquid milk (+23%), but no more efficient at producing milk energy (+2%). L'Huillier et al. (1988) also found that F cows produced more milk and milk solids per cow than J cows, but this was because of their greater DMIs. In this last study, FCE, utilisation of metabolisable energy, and DM consumption per unit liveweight of J cows was higher than for F cows and consequently allowed J cows to achieve higher production per ha than F cows. This has also been observed by Bryant (unpubl. data). L'Huillier et al. (1988) suggested that a breed comparison at other stages of lactation was warranted, as their study was carried out during the 14th—17th week of lactation. Accurate assessment of FCE of individual grazing animals has been hampered by inadequate techniques to accurately measure individual feed intake of pasture. The recently developed alkane technique (Dove & Mayes 1991) can be used for this purpose, thereby allowing the calculation of FCE for individual cows. The effect of body condition at calving on subsequent production, body condition loss/gain, and intake has been well documented overseas on conserved roughage and concentrate diets (Garnsworthy 1988). However, there are only limited data available for cows grazed on pasture. Studies conducted in New Zealand and Australia show that greater condition at calving has resulted in higher milksolids production yields where pasture forms the basal diet (Hutton & Parker 1973; Rogers et al. 1979; Grainger et al. 1982) as well as a reduction in voluntary DMI under ad libitum pasture allowance (Grainger et al. 1982). Macmillan et al. (1982) found that 2- and 3-year old cows which calved in thin condition had early lactation milk fat production adversely affected to a greater extent than older cows. The current study compared first lactation FCEs, DMIs, milk production, and liveweight changes of 2-year-old primiparous F and J cows that calved at high or low liveweight.

1992. All heifers were born and reared at the Dairying Research Corporation, Ruakura. The F heifers were sired by 4 bulls and the Js by 2 bulls, which were part of the New Zealand Dairy Board's Premier Sire Service team of artificial insemination bulls. The average payment breeding index was 135.7 in the F bulls and 135.8 in the J bulls. Pasture allowance was restricted for 8 animals of each breed (L) during the 8 weeks before the common predicted calving date (15 July 1993) to produce differences in calving liveweight (within breed) of 50 kg. The remaining 8 animals of each breed were fully fed on pasture (H). Pasture allowance assessments, made by pre- and post-grazing estimates of herbage mass and grazing area measurements, and weekly liveweight (LW) and condition score (CS) measurements were used to guide pre-calving feeding levels. Calving liveweights (CLW) were recorded within 24 h postpartum and thereafter at 14-day intervals at 0900 h following morning milkings. Mean condition scores at calving were 4.8 (FH), 4.5 (FL), 4.5 (JH), and 4.0 (JL).

MATERIALS AND METHODS

Sampling procedures Six days before each intake measurement period (Day 1), cows were dosed twice daily at 0700 and 1600 h, with a gelatine capsule (Dove et al. 1988) containing c. 450 mg of synthetic C32 alkane (Sigma

Animals and experimental design Sixteen F and 16 J conceived to a synchronised first insemination at 15 months of age in October

Pasture and feeding All cows were managed as a single herd following calving, for the remainder of the lactation. The single herd was offered a generous pasture allowance to minimise any effects of competition between F and J cows by providing a new area of pasture after morning (0700 h) and evening ( 1600 h) milkings. Post-grazing herbage mass residuals were monitored daily by visual estimation, and did not fall below 1800 kg DM/ha. This was to provide pasture allowance conditions (40—50 kg DM/cow per day) where each heifer could express its appetite. It was estimated that pasture DMI for the largest F heifer could have been as high as 15 kg DM/day under this nutritional regime. Measurement and sample collection procedures Dry matter intake Individual voluntary DMIs were measured using the alkane technique (Dove & Mayes 1991) during 7 periods as outlined below.

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Mackle et al.—Effects of breed and calving liveweight on feed conversion efficiency Co.), to achieve a total daily dose rate of c. 900 mg of C32. This 6-day equilibration period was to ensure that faecal concentrations of C32 had reached equilibrium before any faecal sampling (Mayes et al. 1986). From Days 7 to 12, faecal samples (c. 200 g wet weight) were obtained per rectum in holding bails twice daily, immediately before dosing and morning (0700 h) and evening ( 1600 h) milkings. These morning and afternoon samples were dried immediately in an oven at 60°C for 4 days. The samples were then finely ground and bulked together by obtaining 1 g from each of the morning and afternoon samples collected over the previous 6 days, to form one composite faecal sample for subsequent alkane analysis. Representative pasture samples were collected every second day from Days 6 to 11, to coincide with faecal collection from Days 7 to 12, allowing for the delay in the appearance of pasture alkanes in faeces, caused by rate of passage. Approximately 50 hand-clipped pasture samples were taken with hand-shears from each new allocation of pasture offered to the cows during Days 6-11. Herbage samples collected from each 12-h allocation were bulked each day to form 6 daily samples, which were then frozen, freeze-dried, and finely ground before alkane analysis. A subsample was removed every day for a proximate analysis ofthat pasture. Alkane analytical procedures The analytical procedures to measure alkane concentrations were essentially those described by Mayes et al. (1986) using an automated GLC

Table 1 Alkane measurement periods used to determine individual DMIs of young F and J cows during the 1993/94 season (July 1993 to May 1994). Date 15 Jul 2-7 Aug 5-10 Sep 3-8 Oct 31 Oct-5 Nov 12-17 Dec 13-18 Feb 1 Apr 22-27 May

Days since calving 0 18-23 52-57 80-85 108-113 150-155 213-218 260 311-316

Measurements Mean calving date DMI, LW, MYC, PCC DMI, LW, MYC, PCC DMI, LW, MYC, PCC DMI, LW, MYC, PCC DMI, LW, MYC, PCC DMI, LW, MYC, PCC All cows dry DMI, LW, PCC

DMI = dry matter intake by n-alkanes LW = liveweight measurements MYC = milk yield and composition PCC = pasture chemical and botanical composition

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(5890A; Hewlett-Packard, Avondale, PA). The accuracy of this technique for use in dairy cows is discussed elsewhere (Dillon & Stakelum 1988; Dillon & Stakelum 1989; Stakelum & Dillon 1990). Pasture proximate analyses Nitrogen content of pasture was determined in a micro-Kjeldahl digest (Model 16210; Foss Electric, Denmark) by reduction with alkaline sodium phenate (Gehrke et al. 1972). Pasture organic matter contents were analysed according to the method of the AOAC (1984). Pasture samples for in vitro digestibility analysis were oven-dried at 60°C for 16 h before analysis using the method of Tilley & Terry (1963). Neutral (NDF) and acid (ADF) detergent fibre contents in pasture were determined using the method of Goering & Van Soest (1970). Milk yield and composition and liveweight Milk yield and composition were routinely measured throughout lactation on a composite sample obtained at Monday afternoon and Tuesday morning milkings. During DMI estimation periods, milk yield and composition were additionally measured on Thursday afternoon and Friday morning milkings. Samples were analysed for milk protein, milk fat,and lactose with a Milkoscan 133B (Foss Electric, Denmark). The criterion used to end a lactation was daily milk yield, so that F and J animals were dried off when individual daily milk yields fell below 5 or 4 kg/cow per day, respectively. Calculations Daily pasture DMI was estimated using the following equation: DMI (kg/cow per day) = {(Dj ///,•) * (Fj IF; -Hj)} where Dj = daily dose of C32 alkane (mg/cow per day); and Fj = herbage and faecal C32 alkane H j concentrations (mg/kg DM); and Ht and Ft = herbage and faecal C33 alkane concentrations (mg/kg DM) (Dove & Mayes 1991). The following equations and parameters were assumed in the energy balance data: ME for Maintenance (MEM) = 0.60 x LW 075 MJ ME/day (Holmes et al. 1987) Energy value of gain 1 -where KB = 0.65 ME„ K„

(Holmes et al. 1987).

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The efficiency of utilisation of energy mobilised from body tissues for milk synthesis (Kg >]) was assumed to be 0.83 (Holmes et al. 1987). ME requirements above maintenance for pregnancy were assumed to be 8.2 MJ/cow per day (during the May period only) (ARC 1980). The energy concentration of milk (MJ/kg) was related to the composition of milk (g/1000 g) using the equations of Grainger et al. (1983): Friesian milk E = 0.0381 (± 0.003) x Fat + 0.0284 (± 0.006) x Protein + 0.482 Jersey milk E = 0.0291 (± 0.002) x Fat + 0.0337 (± 0.006) x Protein + 1.059 Solids-corrected milk yield = SCM (kg) = 12.3 * Fat (kg) + 6.56 * Solids-not-fat (kg) -O.0752 * milk yield (kg) (Tyrrell & Reid 1965) Fat-corrected milk yield (4%) = FCM (kg) + milk yield (kg) * (0.4 + 0.15 * Fat %) (Gaines 1928) Gross Ee = Milk energy output divided by ME intake x 100 Gross Ep = Milk protein output divided by protein intake x 100 Gross Ee-LWGL = (Milk energy) — (energy released from body tissue)

100

(ME intake) - (energy required for liveweight gain)

Statistical procedures One JL heifer was removed because of uterine metritis. Data from the remaining 31 animals were subjected to separate analysis at each measurement period as well as analysis of full lactation averages, utilising the general linear models procedure of SAS (SAS Version 6, SAS Institute Inc., Cary, NC, USA). The model included CLW treatment, breed, period, and the CLW by breed, CLW by period, and breed by period interactions. The main

effects of CLW and breed were tested using between-cow error terms. Contrasts shown in all tables were: (1) H versus L CLW; and (2) F versus J breed. The interactions between CLW and breed, CLW and period, and CLW and period are only mentioned when statistically significant (P < 0.05). RESULTS Chemical and botanical composition of pasture Pasture crude protein (CP) levels peaked during August (26.3%) but then varied from 17.9% (September) to 25.7% (December) (Table 2). NDF levels also fluctuated throughout the season, whereas in vitro digestibility values were highest from August to October (Spring) and lowest during February (Summer). ADF and OM contents were relatively constant across the whole lactation (Table 2). The pastures grazed during August, September, and October were predominantly perennial ryegrass (Lolium perenne) (85.3, 89.4, and 78.5%, respectively), with some Poa spp. (12.4, 0.4, and 12.6%) and little white clover (Trifolium repens) (0.2, 5.0, and 4.2%). From November onwards, white clover contents increased (10.3-17.2%) and Poa spp. contents decreased to eventually disappear from the sward. Ryegrass contents declined to 55.3% in February, which corresponded with higher proportions of dead ryegrass and "other" species (14.1%), and a peak in white clover content (17.2%). Liveweight Differential pre-calving nutrition produced CLWs of 404 (FH), 354 (FL), 334 (JH), and 277 (JL) kg, with significant breed (P < 0.0001) and pre-calving

Table 2 Crude protein (CP), neutral detergent fibre (NDF), acid detergent fibre (ADF), organic matter (OM), and in vitro digestibility (Dg) of pastures grazed throughout the season (% DM basis) and relative to days since calving (DSC). Date 2-7 Aug 5-10 Sep 3-8 Oct 31 Oct-5 Nov 12-17 Dec 13-18 Feb 22-27 May

DSC

CP

NDF

ADF

OM

20 54 82 110 152 215 318

26.3 17.9 20.4 22.3 25.7 22.4 19.0

50.9 42.6 44.0 46.6 49.4 43.6 44.3

21.1 20.6 21.6 22.5 21.4 22.5 21.0

89.4 90.7 90.4 90.0 90.2 90.2 89.6

Dg

81.0 82.9 82.8 80.0 78.7 73.7 80.3

Mackle et al.—Effects of breed and calving liveweight on feed conversion efficiency Fig. 1 Mean liveweight from 0 to 316 days since calving for young Friesian cows calving at high (P) or low (p) liveweight and young Jersey cows calving at high (K) or low (k) liveweight (n = 31). SED values between all treatment groups are shown above the x-axis.

361

500

450

400

•S

350

~

300

"

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250

T T T T T T T T T T T T T T T T T T T TT T T

200

-100

-50

0

50

100

150

200

250

300

350

Days since calving

nutrition (P < 0.0001) effects (Table 3). This reduction in CLW achieved through restricted feeding, was proportionately greater in J than F cows (17.1 versus 12.4%). Cows with lower CLW gained more weight throughout lactation (P < 0.0001; Table 3 & Fig. 1) and up until 313 days since calving (DSC) (P < 0.0001). During the first 56 days of lactation, both F and J HCLW cows lost LW, while LCLW

cows of both breeds gained LW (P < 0.0001). There was a CLW by breed interaction for LW change during the first 56 days of lactation; JL cows initially lost LW and then gained less LW over this period than FL cows (Fig. 1 & Table 3). In addition, JH cows lost more LW over this period than FH cows (P < 0.002). When LW gain was expressed as a percentage of initial CLW, LCLW cows gained significantly more LW from calving

Table 3 Adjusted means for liveweight (LW) of young Friesian or Jersey cows of either high (H) or low (L) calving liveweight (CLW), relative to days since calving (DSC). Friesian Mean calving LW LCLW % HCLW a Mean LW 313 DSC LW 0-56 DSC b LW 0-240 DSC b LW 0-313 DSC b LW % 0-56 DSC c LW % 0-240 DSC cd LW % 0-313 DSC c

Jersey

H

L

404 453 -8.9 28.6 42.7 -2.2 7.3 10.6

354 12.4 446 33.4 59.5 92.5 9.5 16.9 26.3

H

L

SED

334

277 17.1 353 10.4 62.4 76.7 3.9 22.8 28.1

14 — 13 8.5 15.6 12.7 2.5 4.6 4.2

350 -25.9 -4.3 16.1 -7.4 -0.7 5.4

Main effects Breed CLW P< 0.0001 P< 0.0001 P < 0.05 NS P