In¯uences of the number of fetuses and levels of CP and ME in
gestation and lactation supplements on performance of Spanish
does and kids during suckling and post-weaning
D.S. Ivey
a, F.N. Owens
b, T. Sahlu
a,*, T.H. Teh
a, L.J. Dawson
c,
G.A. Campbell
c, A.L. Goetsch
aaE (Kika) de la Garza Institute for Goat Research, Langston University, Langston, OK, 73050, USA bAnimal Science Department, Oklahoma State University, Stillwater, OK, 74078, USA cCollege of Veterinary Medicine, Oklahoma State University, Stillwater, OK, 74078, USA
Accepted 11 June 1999
Abstract
Forty-eight mature US Spanish does (40 kg BW), from a herd selected for cashmere ®ber growth, were used to investigate in¯uences of the number of fetuses and levels of ME and CP in supplements during gestation and lactation on doe and kid performance. At 60 days of gestation, does with single or twin fetuses consumed mature Bermudagrass hayad libitumand 1% BW (DM basis) of supplements with 18.6% or 28.5% CP (LP and HP, respectively) and 2.2 or 2.8 Mcal/kg ME (DM basis; LE and HE, respectively). The HE-HP supplement was offered at 1.5% BW (DM basis) for 15 days after birth, and does received the same supplement treatments as in gestation thereafter until weaning at 50 days after parturition. For a 50-day post-weaning period, kids consumedad libitumthe HE-LP supplement. BW at 90 days of gestation (41.4 vs 38.4 kg;P<0.10), BW before parturition (46.1 vs 41.7 kg;P<0.05), BW loss from parturition to day 21 of lactation (8.38 vs 5.25 kg;P<0.05), litter birth weight (5.47 vs 2.75 kg;P<0.05) and plasma concentrations ofb-hydroxybutyrate (0.33 vs 0.29 mM;P<0.05) and NEFA (538 vs 434 mEq/l;P<0.05) were greater for does with twin vs single kids. BW at weaning was similar between single and twin kids (P>0.10; 8.31 and 7.63, respectively). Kid BW and cashmere ®ber weight after the post-weaning period were affected by interactions (P<0.05) between number of fetuses and supplement ME level; kid BW was 12.3, 14.7, 14.6 and 13.2 kg (SE1.12 and 0.68 kg for singles and twins, respectively), and kid cashmere weight was 86, 109, 106 and 102 g (SE8.5
and 5.0 g for singles and twins, respectively) for single-HE, single-LE, twin-HE and twin-LE, respectively. In conclusion, effects of supplements differing in levels of ME and in ingredient composition for US Spanish does in gestation and lactation had dissimilar impacts on post-weaning BW and cashmere weight of single and twin kids. However, because of the limited number of observations and the high variability among animals in measures such as cashmere ®bre growth, further experimentation concerning the potential for effects of nutritional plane of does on cashmere growth by kids is warranted.
#2000 Elsevier Science B.V. All rights reserved.
Keywords:Spanish goat; Cashmere; Supplement
*Corresponding author. Tel.: +1-405-466-3836; fax: +1-405-466-3138.
E-mail address:sahlu@mail.luresext.edu. (T. Sahlu).
1. Introduction
Research with Australian feral goats, of unknown breed origin and unselected for cashmere ®ber growth, has shown little or no effects of plane of nutrition on cashmere ®ber production with basal nutritional planes adequate for BW maintenance (Ash and Northon, 1984; Ash and Northon, 1987a,b; KloÈren et al., 1993). However, it is unclear if such ®ndings are of similar applicability to other breeds or types of goats that grow cashmere ®ber, or with other produc-tion condiproduc-tions. The Spanish goat herd of Langston University had been selected for cashmere growth for several years preceding this experiment and, therefore, might differ from Australian feral goats in response to dietary variations. In addition, interactions between dietary protein and energy levels withad libitumfeed intake in effects on cashmere ®ber growth have not been extensively investigated. Ash and Northon (1984) studied interactions between protein and energy intakes in cashmere ®ber growth in young Australian feral goats. However, energy intake was varied throughad libtiumvs restricted consumption of a pelleted diet, and the proportion of ingested ME available to non-visceral tissues may differ between restricted intake of a particular diet and ad libitum
consumption of diets varying in ingredient composi-tion and between pelleted and other diet physical forms (Goetsch, 1998b).
Pregnancy and lactation appear to in¯uence mohair growth via competition for nutrients between skin follicles and other tissues (Russel, 1992). Conversely, based on research with Australian feral goats, effects of pregnancy and lactation on cashmere ®ber growth are due to physiological changes associated with pregnancy and lactation rather than via nutrient com-petition, which impact times of cashmere cessation and initiation in the growth cycle (KloÈren and Norton, 1993). But as noted before, it is unclear whether such research also can be applied to other types of goats used to produce cashmere ®ber.
Secondary follicle initiation in Australian feral goats occurs at 90±100 days of gestation, and second-ary follicle development continues until approxi-mately 8 weeks of age. Effects of the nutritional plane of does in the last one-third of gestation and of kids during suckling also have not been extensively studied. In one report (Norton et al., 1996), neither
dietary protein level (24% vs 12%) nor energy restric-tion (ad libitumvs 70% of ad libitum intake) for does affected patterns of secondary follicle development in kids. However, it was concluded that evidence was derived suggesting that immediately post-natal nutri-tion of kids affects the number of secondary follicles at shearing at 301 days of age. Objectives of this research were to determine effects of supplement levels of ME and CP for US Spanish does, from a herd selected for cashmere ®ber production, in gestation and lactation on performance of does and kids during suckling and post-weaning.
2. Materials and methods
2.1. Animals, treatments and samples
Forty-eight mature US Spanish goats (40 kg BW), from a herd selected from high cashmere ®ber pro-duction, were used in the experiment, with a 222 factorial arrangement of treatments. Breeding dates were recorded and pregnancy status and the number of fetuses were determined by ultrasonography 45 and 60 days after the last mating of each doe. At 60 days, does were assigned randomly, within groups with single or twin fetuses, to the four dietary or supple-ment treatsupple-ments. Initially, each treatsupple-ment had eight does bearing a single fetus and four does bearing twins. Two does bearing a single fetus aborted between 114 and 125 days of gestation and two gave birth to triplets; thus, data from these animals were not analyzed. Dietary treatments consisted of two supple-ment concentrations of CP (18.6% and 28.5% DM, denoted as LP and HP, respectively) and two of ME (based on NRC, 1981; 2.2 and 2.8 Mcal/kg DM, denoted as LE and HE, respectively) (Table 1). Sup-plements were normally completely consumed within 30 min, although occasionally small amounts of orts were present.
basis) in the preceding few years. The amount of supplement offered was adjusted based on BW in the middle of this 30-day period. Thereafter, does were moved to a lighted barn and maintained indivi-dually in 1.2 m1.5 m pens, with supplement alloca-tions based on individual BW.
One week prior to and during the parturition period, does were observed for 14 h each day. 85% of the does kidded in a 10-day period, with 90% of the births (i.e., 73 of 81) during daylight. Does were weighed immediately before parturition. Shortly thereafter, each kid was ear-tagged and weighed. Litter weight, number of kids born live and gestation length were recorded. For a 15-day period after parturition, all does received the HE-HP supplement at 1.5% BW (DM basis). Thereafter, does received their prepartum supplements.
For lactation measurements, 16 twin-bearing and 12 single-bearing does were used. To prevent kid con-sumption of supplement, kids were separated from does and allowed to suckle for 1 h periods at 0800 and 1530 h daily up to 28 days of age and once daily thereafter at 0800 h until weaning at 50 days of age.
Milk intake was estimated from the difference in BW before and after suckling on day 15 through 45 of lactation. Kids had free access to a commercial grain-based starter diet at 4 weeks of age, although con-sumption was negligible.
Kids were weaned at 50 days of age and fed the HL supplement as the sole diet for 50 days. Each kid was maintained individually in pens used earlier and offered feed, once daily, forad libitumconsumption. Orts were removed, weighed and sampled twice weekly. Kids were weighed before feeding every 2 weeks and at the end of the 50-day post-weaning period.
Blood was sampled from does prior to feeding at 100, 115, 130 and 145 days of gestation and on the day of parturition, via jugular venipuncture into 10 ml vacuum tubes (Becton Dickenson Vacutainer Systems, Rutherford, NJ) containing either K3EDTA or potas-sium oxalate with sodium ¯uoride. Blood samples were similarly obtained from kids at 5, 21, 50 and 100 days of age. Does were sheared on day 100 of gestation and kids at the end of the post-weaning period.
Table 1
Supplement composition
Item Supplementa
HE-HP HE-LP LE-HP LE-LP
Ingredient
Ground corn 43.70 57.49 ± 19.66
Rolled oats ± 11.37 ± ±
Soybean meal 53.41 28.11 45.05 19.22
Alfalfa meal ± ± 51.48 57.66
Limestone 0.99 1.04 1.19 1.19
Dicalcium phosphate 0.35 0.37 0.42 0.42
Trace mineral saltb 0.75 0.78 0.90 0.89
Vitamin premixc 0.80 0.84 0.96 0.96
Nutrient composition
DM (% as-fed) 89.43 89.50 91.50 90.95
CP (% DM) 28.24 18.60 28.70 18.65
NDF (% DM) 19.63 16.25 32.15 33.70
ADF (% DM) 4.60 4.95 20.00 19.25
Ash (% DM) 6.47 5.40 10.80 9.50
ME (Mcal/kg DM)d 2.82 2.81 2.29 2.20
aHE
high ME; LElow energy; HPhigh CP; LPlow CP.
b95.5±98.5% NaCl and >0.24% Mn, 0.24% Fe, 0.05% Mg, 0.032% Cu, 0.011% Co, 0.007% I, and 0.005% Zn. c2200 IU/g vitamin A, 1200 IU/g vitamin D
2.2. Measures and analyses
Feedstuff samples were dried for 48 h at 658C, allowed to air-equilibrate and ground in a Wiley to pass a 1 mm screen. Ground feed samples were ana-lyzed for DM, ash (AOAC, 1990), N (Technicon Instruments, Tarrytown, NY), ADF and NDF (Goering and Van Soest, 1970).
Blood sample tubes were immediately chilled after collection in an ice bath, transported to the laboratory and centrifuged at 1500g and 48C for 20 min. Ali-quots of plasma were stored atÿ208C until analysis. b-Hydroxybutyrate concentration was determined using the GDS Stat-site Meter with appropriate GDS Test Cards and controls (GDS Diagnostics, Division of GDS Technology, Elkhart, IN). Concen-trations of urea-N, glucose and total protein for does and urea-N and total protein for kids were assayed colorimetrically using a Technicon AutoAnalyzer II System (Technicon Instruments, Tarrytown, NY). NEFA concentration was determined using a commer-cially available kit (Wako Chemicals USA, Rich-mond, VA).
At shearing, total ¯eece weight was recorded and a representative ¯eece sample was taken. A Shirley analyzer was used to determine the proportion of ®ne cashmere ®ber that could be mechanically separated from coarse guard hair as previously described by Lupton (1993). For cashmere length measurement, two 1 g aliquots were randomly sampled and manually separated into cashmere and hair ®bers. Cashmere length was measured under a microscope to the near-est 0.5 mm and cashmere ®ber diameter was measured using an Optical Fiber Diameter Analyzer (Baxter et al., 1992).
2.3. Statistical analyses
Statistical analyses were conducted using the GLM procedure of SAS (1985). Data were analyzed with a 222 factorial arrangement of treatments and a completely randomized design. The model included number of fetuses, supplement ME level, supplement CP level, number of fetusesME level, number of fetusesCP level, MECP levels, number of fetu-sesME levelCP level and residual error, with residual error used to determine signi®cance. Mea-sures at different times were analyzed as a split-plot in
time. Measures averaged over time were analyzed as described above when interactions between main effects and time were non-signi®cant (P>0.10), and analyses were conducted separately for each time when a time interaction was signi®cant.
3. Results
3.1. Does
Gestation length was less (P<0.10) for LE vs HE (Table 2). Because of greater BW for does bearing twins vs singles at 90 days of gestation (P<0.10) and at parturition (P<0.05), supplement DM intake was greater (P<0.05) for does bearing twins. BW gain from day 90 until just before parturition (Fig. 1) was affected by an interaction between the number of fetuses and supplement levels of ME and CP (P<0.05). For twin-bearing does, these measures were similar among supplement treatments, but for does with single kids ranked LE-LP>HE-HP>HE-LP and LE-HP. BW loss from just before parturition to day 21 of lactation was greater (P<0.05) for twin- vs single-bearing does. Kid birth weight was similar among treatments (P>0.10) though litter birth weight for does with twins was approximately twice that of does with single kids (P<0.05).
Total ¯eece weight of does at 90 days of gestation was not affected by treatments (P>0.10) but was greater (P<0.10) for does with twins than singles (Table 2). Cashmere weight (P<0.10), percentage of total ¯eece (P<0.05) and length (P<0.05) were less for HP vs LP.
Plasma glucose concentration during gestation in does was similar among treatments (P>0.10; Table 2). Plasma concentrations of b-hydroxybutyrate and NEFA were greater (P<0.05) for does with twins vs single kids and for LE than for HE. Total protein concentration in plasma was similar (P>0.10) among treatments, and the urea-N concentration was greater (P<0.05) for HP than for LP. Milk production was greater (P<0.05) for twin- vs single-bearing does (Table 2).
3.2. Kids
similar difference was noted on day 50 (Table 3). Initial BW in the post-weaning period on day 51 was similar (P>0.10) among treatments. DM intake in g/day was similar (P>0.10) between single and twin kids but was greater (P<0.05) for twins as % BW . Twin kid ADG during the post-weaning period was greater (P<0.05) than that for single kids. Kid BW on day 100 (Fig. 2) from day 51 to 100 (Fig. 2) were affected by an interaction (P<0.05) between the num-ber of fetuses and supplement ME level, with means being greater for LE vs HE with single kids but lower for LE than for HE with twins.
Total ¯eece weight for kids on day 100 was similar among treatments (P>0.10; Table 3). Cashmere weight was affected by an interaction (P<0.05) between the number of fetuses and supplement ME level (Fig. 3). Cashmere ®ber weight was similar between supplement ME levels with twins but with single kids was greater for LE vs HE. Cashmere ®ber diameter was greater (P<0.05) for LP vs HP. Plasma total protein and urea-N concentra-tions were similar among treatments on day 50 and 100, as was also the case for glucose on day 100 (P>0.10; Table 3).
Table 2
Effects of number of fetuses and levels of supplemental ME and CP during gestation and lactation of Spanish does on BW, fleece characteristics and plasma measures
Item Number of fetuses SE Supplement ME level SE Supplement CP level SE
One Two High Low High Low
Gestation
Total length (day) 148.0 147.6 0.91 148.7c 146.9d 0.78 148.2 147.4 0.77
Supplement intake (g/day) 387a 428b 15.0 410 404 13.0 410 404 12.7
Doe BW (kg)
Day 90 of gestation 38.4c 41.4d 1.47 40.3 39.4 1.26 40.4 39.4 1.25
Before parturition 41.7a 46.1b 1.63 44.3 43.5 1.40 44.3 43.5 1.39
Day 21 post-partum 36.4 37.7 1.33 37.9 36.2 1.14 37.6 36.5 1.13 Loss, parturition to day 21 5.25a 8.38b 0.93 6.34 7.29 0.80 6.63 7.00 0.79
Kid birth weight (kg) 2.75 2.74 0.08 2.80 2.69 0.07 2.75 2.74 0.06 Litter birth weight (kg) 2.75a 5.47b 0.14 4.18 4.05 0.12 4.13 4.10 0.12 Fleece measures, gestation day 100
Total fleece (g) 377 397 21.3 402 372 18.4 386 388 18.1 Guard hair (g) 231 245 20.9 247 228 18.1 249 226 17.8 Cashmere fiber (g) 146 153 16.1 155 144 13.9 137c 162d 13.7
Percentage of total fleece 39.5 38.5 3.91 40.0 38.0 3.38 35.8a 42.2b 3.32
Diameter (mm) 18.2 18.0 0.33 18.2 18.0 0.29 17.9 18.3 0.28 Length (mm) 58.9 63.0 3.47 60.8 61.1 2.97 57.9a 64.0b 2.95
Plasma, gestation
Glucose (mg/dl) 60.3 59.2 4.03 63.4 56.1 3.43 62.8 56.7 3.42
b-hydroxybutyrate (mM) 0.29a 0.33b 0.02 0.29a 0.33b 0.02 0.31 0.31 0.02
NEFA (mEq/l) 434a 538b 28.1 461a 511b 24.1 484 488 24.6
Total protein (g/l) 92.9 99.0 7.87 100.2 91.6 6.77 95.1 96.8 6.90 Urea-N (mg/l) 22.8 24.8 1.15 24.3 23.3 0.98 25.8b 21.8a 0.97
Milk production (kg/day) 0.84a 1.31b 0.07 1.08 1.07 0.07 1.07 1.09 0.07
a,bWithin a row and grouping of number of fetuses, supplement ME level or supplement CP level, means without a common superscript
letter differ (P<0.05).
c,dWithin a row and grouping of number of fetuses, supplement ME level or supplement CP level, means without a common superscript
4. Discussion
4.1. Does
4.1.1. Body weight
Greater doe BW during gestation and immediately before parturition with twins vs single kids in part relates to greater supplement DM intake, although hay intake might have differed between does with one or two fetuses as well. The magnitude of difference in
litter birth weight between single- and twin-bearing does indicates that greater doe BW with twins before parturition was due not only to the fetus but also, to a lesser extent, to maternal tissues. However, because greater BW loss by does with twins vs singles from the time immediately before parturition to day 21 of lactation can be accounted for by the difference in litter weight, single- and twin-bearing does appeared to loose similar BW in the ®rst 21 days of lactation even though milk production was greater with twins. Factors responsible for the interaction between the number of fetuses and supplement ME and CP levels in doe BW gain from day 90 of gestation until immediately before parturition are unclear. Although, conceivably differences among supplements in the ratio of ruminally degradable protein to fermentable OM and between nutrient demand by does bearing one vs two fetuses may have been involved. Given the impact of nutrient demand on feed intake (Ketelaars and Tolkamp, 1996), the lack of supplement treatment effects on BW gain of does bearing twins may relate to the high demand or potential for use of nutrients relative to that of does with singles. For does with a single fetus, BW gain could have been limited for HE-LP because a suboptimal ruminal ammonia-N con-centration was elicited by the low ratio of ruminally degradable N to fermentable OM in supplement, which restricted forage digestion and (or) intake (Poppi and McLennan, 1995). Lower BW gain for
Fig. 1. BW gain of Spanish does, from day 90 of gestation to immediately before parturition, receiving supplements (1% BW, DM basis) differing in ME (2.2 and 2.8 Mcal/kg ME for LE and HE, respectively) and CP levels (18.6% and 28.5% CP for LP and HP, respectively) and bearing single or twin fetuses. SE1.05 and 0.74 kg for single- and twin-bearing does, respectively.
Fig. 2. Post-weaning BW of kids at 100 days of age from Spanish does receiving gestation and lactation supplements (1% BW, DM basis) differing in ME (2.2 and 2.8 Mcal/kg ME for LE and HE, respectively) and CP levels (18.6% and 28.5% CP) and bearing single or twin fetuses. SE1.12 and 0.68 kg for single and
twin-bearing does, respectively.
Fig. 3. Cashmere weight for kids at 100 days of age from Spanish does receiving gestation and lactation supplements (1% BW, DM basis) differing in ME (2.2 and 2.8 Mcal/kg ME for LE and HE, respectively) and CP levels (18.6% and 28.5% CP) and bearing single or twin fetuses. SE8.5 and 5.0 g for single and
LE-HP vs LE-LP might relate to differences in sup-plement concentrations of corn and soybean meal. Low-level starch supplementation has in some instances had small positive effects on ®ber digestion (Goetsch and Owens, 1987), and ruminal microbes derive very little energy from degradation of protein and amino acids (Owens and Goetsch, 1988).
In late pregnancy, ruminants often exhibit increased blood concentrations of NEFA and ketone bodies, which re¯ect inadequate supplies of absorbed energy or glucose (Pethick and Lindsay, 1982; Pethick et al., 1983; Chandler et al., 1985; Bell, 1993). NEFA are mobilized from body fat stores to meet a shortage of dietary energy; BHBA, one of the ketone bodies, is released from the liver when fatty acids from depot fat are released faster than can be oxidized by the liver. In
accordance, the correlation between NEFA and b -hydroxybutyrate concentrations in the present experi-ment was positive (r0.57; P<0.001). Both NEFA and b-hydroxybutyrate can be oxidized by skeletal muscle and the pregnant uterus (Pethick and Lindsay, 1982; Chandler et al., 1985). Greater use of maternal energy stores during the last trimester of gestation by does with twins vs singles presumably minimized the difference in doe BW at parturition.
4.1.2. Fleece
Does were sheared in February, near the end of the cashmere growing cycle. The impact of supplement CP level on cashmere weight and length occurred after only 40 days of supplementation, with even a shorter period of potential impact of supplement treatments
Table 3
Effects of number of fetuses and levels of supplemental ME and CP for Spanish does during gestation and early lactation on BW, fleece characteristics and plasma measures for Spanish kids during suckling and early post-weaning
Item Number of fetuses SE Supplement ME level SE Supplement CP level SE
One Two High Low High Low
Suckling period, litter weight
Day 12 (kg) 3.81a 7.58b 0.44 5.75 5.64 0.42 5.82 5.57 0.42
Weaning, day 50 (kg) 7.61a 14.1b 0.74 11.0 10.7 0.70 10.8 11.9 0.70
ADG, day 12±50 (g/day) 109a 186b 11.8 151 144 11.2 143 152 11.2
Post-weaning period, kid, day 51±100
Initial kid BW (kg) 8.31 7.63 0.41 7.93 8.01 0.34 7.84 8.10 0.34 ADG (g/day) 105a 126b 10.3 111 119 8.5 113 117 8.5
DM intake (g/day) 333 367 17.3 345 355 14.5 354 346 14.5 % BW 2.46a 2.65b 0.07 2.55 2.56 0.06 2.62 2.50 0.06 Fleece measures
Total fleece (g) 97.4 104.3 7.70 96.0 105.7 6.41 97.1 104.6 6.41 Cashmere fiber
Weight (g) 39.8 46.3 5.19
Diameter (mm) 18.4 17.1 0.93 18.6 16.9 0.78 16.4a 19.1b 0.79 Length (mm) 32.2 34.8 1.94 34.9 32.1 1.62 32.2 34.8 1.62 Plasma
Day 50
Total protein (g/l) 58.9a 66.6b 2.86 62.3 62.1 2.47 61.2 63.3 2.45
Urea-N (mg/dl) 25.0 23.3 2.03 23.5 24.8 1.74 24.9 23.4 1.77 Day 100
Total protein (g/l) 63.7 67.0 2.43 63.8 66.8 2.02 67.2 63.5 2.02 Urea-N (mg/dl) 23.8 23.4 2.16 24.0 23.1 1.79 23.7 23.5 1.79
a,bWithin a row and grouping of number of fetuses, supplement ME level or supplement CP level, means without a common superscript
letter differ (P<0.05).
c,dWithin a row and grouping of number of fetuses, supplement ME level or supplement CP level, means without a common superscript
considering time required for change in ®ber diameter and for ®bers to reach skin level for removal (Downes and Sharry, 1971; Reis and Tunks, 1976; Nagorcka, 1977). Thus, factors responsible for this supplement CP level response are not easily discernible.
Greatest differences between does with single and twin fetuses in nutrient demands are in the last one-third of gestation, which after shearing at day 100 of gestation in this experiment. The number of fetuses did not alter ¯eece produced by does. Therefore, with normal management practices in this area of the USA, entailing shearing nearly 2 mo before kidding, with a moderate plane of nutrition the number of fetuses may have little impact on production and characteristics of cashmere produced by the doe.
4.2. Kids
4.2.1. Suckling
The difference between does with one or two fetuses in milk production and change in BW from before parturition to day 21 of lactation indicate that does were in a moderate plane of nutrition during lactation, as in gestation, due to the relatively high level of supplemental concentrate, with absorbed nutrients adequate to support a rate of growth of twin kids nearly as rapid as that of single kids. In sheep, as is also expected in goats, a low nutritional plane in lactation can have greater impact on dam BW loss and (or) weight gain by twin vs single progeny (Goetsch, 1998a). However, it is important to note that in the present experiment litter weight and ADG from day 12 to 50 of the suckling period of litters with twins were not quite twice as great as that of single kid-litters. This agrees with the difference in milk production between single- and twin-bearing does less than 100% greater than that with single fetuses. Slightly lower twin vs single kid ADG during suckling might have resulted from lower total ME intake by does than necessary for production of a quantity of milk suf®cient for comparable twin and single kid ADG and (or) have been a consequence of limited milk production potential of the does. In accordance, earlier it was mentioned that the differ-ence in maternal energy stores at parturition between does with single and twin kids was not marked, limited part by, greater energy mobilized with twins in late gestation.
4.2.2. Post-weaning
Greater post-weaning kid ADG and DM intake relative to BW for twins vs singles was probably caused by compensatory growth that was a conse-quence of the slight limitation of twin kid ADG during the suckling period. Limited milk intake can hasten development and function of the digestive system early post-weaning (Hamada et al., 1976) and stimu-late solid feed consumption by goat kids (Lu et al., 1988).
Interactions in kid BW and cashmere weight at day 100 between the number of fetuses and supple-ment level of ME for does during gestation and in much of the lactation period cannot be presently explained. Although the magnitude of the BW inter-action was considerable, the limited number of obser-vations raise the possibility of a less than ideal allocation to treatments. Nonetheless, assuming the allotment acceptable, these interactions imply that there was a trend for a similar interaction in post-weaning ADG or doe milk production and resultant kid BW on day 51. The latter postulate seems more plausible, and is in general accordance with that given earlier for an interaction in doe BW loss from day 90 of gestation to parturition. A possible framework of logic for these interactions in kid BW and cashmere ®ber weight at day 100 can be put forward, which would however require further experimentation to con®rm or refute.
rumen available for microbial actions and particle size reduction via rumination. Conversely, with the lesser demand for energy use in milk production by does with single kids, lower ®ber digestibility for HE vs LE supplements could have had appreciable effect onad libitumfeed intake and milk production. Possible end-results of these conditions are greater cashmere ®ber weight for LE vs HE with singles but not twins and greater post-weaning BW for LE-singles and HW-twins than for HE-singles and LE-HW-twins.
5. Conclusions
With a moderate plane of nutrition during gestation elicited by ad libitum consumption of low-quality grass hay and a relatively high level of supplemental concentrate, the number of fetuses did not affect cashmere weight of US Spanish does from a herd selected for cashmere ®ber production, with shearing in February at 100 days of gestation. Different supple-ment ME and CP levels during gestation and lactation periods did not in¯uence birth weight of single or twin kids. Kid BW and cashmere weight after 50-day suckling and post-weaning periods were affected by an interaction between the number of fetuses and level of ME in supplements given to does in gestation and lactation, suggesting possible impact of nutrient demand as in¯uenced by number of fetuses on doe responses to different supplements in milk production and consequent kid BW. However, because of the limited number of observations in this experiments, these ®ndings warrant further research.
Acknowledgements
This research was partially supported by USDA Grant no. 91-38814-6214.
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