scholarly journals Modeling Lactation Curve in Primiparous Beef Cattle

2016 ◽  
Vol 8 (4) ◽  
pp. 116 ◽  
Author(s):  
Ana C. Espasandin ◽  
Verónica Gutierrez ◽  
Alberto Casal ◽  
Ana Graña ◽  
Oscar Bentancur ◽  
...  
Keyword(s):  
Beef Cattle ◽  
Milk Yield ◽  
Repeated Measures ◽  
Fixed Effects ◽  
Post Partum ◽  
Random Effect ◽  
Live Weight ◽  
Coefficients Of Variation ◽  
Lactation Curve ◽  
Milking Machine

<p>The work describes lactation curves and compares two methods to estimate milk yield (MY) in a grazing beef cattle herd of the EEBR Station-Udelar, Uruguay. Twenty-four Hereford, Angus and F1-crossbreed primiparous cows were used to estimate MY once a month, from birth to weaning, by weigh-suckle-weigh (WSW) technique and milking-machine (MM). Milk yield (MY), milk yield retained energy (ReMY), and calf weight were analyzed as repeated measures in a model including: sex of calves, month of lactation, cow and calf breed, milking method, estimation day (1 or 2), and post-partum days as fixed effects, and cow nested within breed as the random effect. The correlation analysis and the Gage r&amp;R coefficient (repeatability and reproducibility) between the two methods were used to study their associations. Lactation curves were compared (AICC and BIC) using Wood (1964), and Jenkins and Ferrel (1984) models. The MY estimated differed with the methodology being WSW higher than MM (P &lt; 0.001). The r&amp;R coefficient (0.83) suggest lower associations between WSW and MM, being 18% and 6% the coefficients of variation, respectively. Cow breed was not significant for MY. Calf live weight and ReMY were negatively associated (-0.52, P &lt; 0.0001). Based on variability observed, MM is more accurate to estimate MY and Wood curve the most adjusted to describe lactation in grazing beef cattle.</p>

scholarly journals PSVIII-17 Assessment of conformational changes across three parities in sows

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 221-222
Author(s):  
Melanie D Trenhaile-Grannemann ◽  
Ronald M Lewis ◽  
Stephen D Kachman ◽  
Kenneth J Stalder ◽  
Benny E Mote
Keyword(s):  
Body Size ◽  
Body Length ◽  
Conformational Changes ◽  
Repeated Measures ◽  
Fixed Effects ◽  
Random Effect ◽  
Joint Angles ◽  
Body Depth ◽  
Conformation Changes ◽  
Over Time

Abstract Conformation-based sow selection is performed prior to reaching mature size, yet little is known about how conformation changes as growth continues. To assess conformation changes, 9 conformational traits were objectively measured at 12 discrete time points between 112 d of age and parity 3 weaning on 622 sows in 5 cohorts. The 9 traits included 5 body size traits (body length, body depth at the shoulder and flank, and height at the shoulder and flank) and 4 joint angles (knee, hock, and front and rear pastern). Data were analyzed with a repeated measures model (SAS V 9.4) including cohort and time point as fixed effects, sire as a random effect, and heterogeneous compound symmetry as the covariance structure. Sire variance ranged from 0.16 (body depth shoulder) to 2.00 (body length) cm2 for body size traits and 2.28 (rear pastern) to 4.22 (front pastern) degrees2 for joint angles. Cohort had an effect on all traits (P &lt; 0.05). All traits displayed changes over time (P &lt; 0.001). Size traits increased between 112 d of age and parity 3 weaning (64.16 vs. 107.57 cm, 26.62 vs. 44.14 cm, 23.32 vs. 36.92 cm, 46.10 vs. 73.55 cm, 49.36 vs. 77.47 cm for body length, body depth shoulder and flank, and height shoulder and flank, respectively); however, they fluctuated within parity by increasing during gestation and decreasing at weaning. Knee angle decreased (164.12 vs. 150.72 degrees) while fluctuating within parity by decreasing in the second half of gestation and increasing after weaning. Front and rear pastern angles decreased over time (60.89 vs. 53.74 degrees and 64.64 vs. 55.50 degrees for front and rear pastern, respectively), while biologically negligible change was observed in hock angle (148.63 vs. 147.48 degrees). Sow conformation changes throughout life, and these changes may require consideration when making selection decisions.

305 Methane Emissions and Apparent Total Tract Nutrient Digestibility of Feedlot Beef Steers Under Intensive Management with or Without an Added Nutritional Packet

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 166-167
Author(s):  
Andrea M Osorio ◽  
Kaue T Tonelli Nardi ◽  
Igor Gomes Fávero ◽  
Kaliu G Scaranto Silva ◽  
Kymberly D Coello ◽  
...  
Keyword(s):  
Treatment Period ◽  
Repeated Measures ◽  
Fixed Effects ◽  
Block Design ◽  
Random Effect ◽  
Methane Emissions ◽  
Nutrient Digestibility ◽  
Experimental Unit ◽  
Beef Steers ◽  
Ch4 Production

Abstract The effects of a nutritional packet were evaluated on CH4 emissions and apparent total tract nutrient digestibility of feedlot beef steers. Thirty Angus-crossbred steers (BW = 542 ± 8.4 kg) were used in a randomized complete block design and allocated into pens equipped with SmartFeed (C-Lock; 15 steers/treatment). Steers were consuming a steam-flaked corn-based diet (88% concentrate DM basis) ad libitum for the last 65 d on feed, and received the following treatments: 1) control and 2) a nutritional packet [0.29% DM basis; live yeast (Saccharomyces cerevisiae; 8.7 Log CFU/g); Vitamin C (5.4 g/kg); Vitamin B1 (13.33 g/kg); NaCl (80 g/kg); KCl (80 g/kg)]. Methane emissions and apparent total tract nutrient digestibility were measured during 3 periods with 5-d of collections each. Gas emissions from steers were measured utilizing the SF6 tracer technique. Feed and fecal samples were collected once and twice (0700 h and 1600 h) daily, respectively, to determine digestibility of nutrients using iNDF as an internal marker. Steer was considered the experimental unit. Data were analyzed as repeated measures using the MIXED procedure of SAS with the fixed effects of treatment, period, and their interaction, and the random effect of block. No treatment × period interactions (P ≥ 0.125) were observed for DMI and any of the CH4 production variables (g/day, g/kg BW0.75, g/nutrient intake, and g/nutrient digested). Moreover, treatments did not affect digestibility of DM, OM, or ADF (P ≥ 0.300); however, digestibility of NDF was increased for treated cattle (P = 0.013), which resulted in a tendency (P = 0.098) to decrease CH4 production in g per kg NDF intake and decreased (P = 0.020) grams CH4 per kg NDF digested. The nutritional packet may be altering ruminal fermentation on intensively managed steers and improving fiber digestibility, which can have benefits on CH4 emission intensity.

scholarly journals PSXI-32 Potential improvements in milk production of mid lactating Holstein cows through changes in the defoliation intensity on a mixed pasture

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 384-385
Author(s):  
Oliver Fast Hinz ◽  
Pablo Chilibroste ◽  
Gabriel Menegazzi ◽  
Matías Oborsky ◽  
Pablo Soca ◽  
...  
Keyword(s):  
Milk Production ◽  
Milk Yield ◽  
Festuca Arundinacea ◽  
Fixed Effects ◽  
Mixed Model ◽  
Body Condition Score ◽  
Random Effect ◽  
Milk Composition ◽  
Control Treatment ◽  
Condition Score

Abstract An experiment was performed to study the effect of two contrasting defoliation intensities of a fescue based pasture on milk production of 24 mid lactating multiparous cows. The animals were blocked according to parity, body weight (587 ± 42 kg), body condition score (2.77 ± 0.16) and calving date, and were randomly allocated to one of these two treatments: lax treatment (TL) 12 cm and control treatment (TC) 6 cm, with four replications. It was used a second-year pasture of Festuca arundinacea and Lotus corniculatus (2530 ± 180 kgDM/ha), divided into eight plots of 0.3 ha. Each plot was grazed by three cows during as many days as necessary until the defoliation height of each treatment was achieved. This would be determined by daily measures of the pasture height. Animals had one grazing session from 8:00 to 16:00 h. Both treatments received 7.5 kgDM of supplementation (17% Crude Protein; 2.81 Mcal/kgDM) in individual troughs. The cows were milked twice a day (05:00 and 17:00 h). Milk production was registered daily while milk composition was measured at the beginning and at the end of the experiment (samples from two consecutive milking). For milk yield results, a mixed model was used (Glimmix procedure, SAS 9.2, 2010) to analyse with treatment, day and their interaction as fixed effects and block as a random effect. While milk composition was analysed with only treatment as fixed effect. Milk yield was greater for TL than TC, while there was no difference in milk composition between treatments (Table 1). There is a significant effect of the day and an interaction between treatment and day (Figure 1), as difference was greater for TL to the end of the grazing period. This leads to the conclusion that it is possible to improve the milk production through less defoliation intensity.

scholarly journals Long-Term Testosterone Therapy Improves Cardiometabolic Function and Reduces Risk of Cardiovascular Disease in Men with Hypogonadism

2017 ◽  
Vol 22 (5) ◽  
pp. 414-433 ◽  
Author(s):  
Abdulmaged M. Traish ◽  
Ahmad Haider ◽  
Karim Sultan Haider ◽  
Gheorghe Doros ◽  
Farid Saad
Keyword(s):  
Repeated Measures ◽  
Fixed Effects ◽  
Random Effect ◽  
Treated Group ◽  
Myocardial Infarctions ◽  
Control Group ◽  
Cv Disease ◽  
High Level ◽  
Changes Over Time

Objectives: In the absence of large, prospective, placebo-controlled studies of longer duration, substantial evidence regarding the safety and risk of testosterone (T) therapy (TTh) with regard to cardiovascular (CV) outcomes can only be gleaned from observational studies. To date, there are limited studies comparing the effects of long-term TTh in men with hypogonadism who were treated or remained untreated with T, for obvious reasons. We have established a registry to assess the long-term effectiveness and safety of T in men in a urological setting. Here, we sought to compare the effects of T on a host of parameters considered to contribute to CV risk in treated and untreated men with hypogonadism (control group). Patients and Methods: Observational, prospective, cumulative registry study in 656 men (age: 60.7 ± 7.2 years) with total T levels ≤12.1 nmol/L and symptoms of hypogonadism. In the treatment group, men (n = 360) received parenteral T undecanoate (TU) 1000 mg/12 weeks following an initial 6-week interval for up to 10 years. Men (n = 296) who had opted against TTh served as controls. Median follow-up in both groups was 7 years. Measurements were taken at least twice a year, and 8-year data were analyzed. Mean changes over time between the 2 groups were compared by means of a mixed-effects model for repeated measures, with a random effect for intercept and fixed effects for time, group, and their interaction. To account for baseline differences between the 2 groups, changes were adjusted for age, weight, waist circumference, fasting glucose, blood pressure, and lipids. Results: There were 2 deaths in the T-treated group, none was related to CV events. There were 21 deaths in the untreated (control) group, 19 of which were related to CV events. The incidence of death in 10 patient-years was 0.1145 in the control group (95% confidence interval [CI]: 0.0746-0.1756; P < .000) and 0.0092 in the T-treated group (95% CI: 0.0023-0.0368; P < .000); the estimated difference between groups was 0.0804 (95% CI: 0.0189-0.3431; P < .001). The estimated reduction in mortality for the T-group was between 66% and 92%. There were also 30 nonfatal strokes and 26 nonfatal myocardial infarctions in the control group and none in the T-treated group. Conclusion: Long-term TU was well tolerated with excellent adherence suggesting a high level of patient satisfaction. Mortality related to CV disease was significantly reduced in the T-group.

Effects of nutrition pre-partum and post partum on subsequent productivity and health of N’Dama cows infected with Trypanosoma congolense

1999 ◽  
Vol 68 (4) ◽  
pp. 819-829 ◽  
Author(s):  
J. J. Bennison ◽  
O. O. Akinbamijo ◽  
J. Jaitner ◽  
L. Dempfle ◽  
C. R. C. Hendy ◽  
...  
Keyword(s):  
Milk Yield ◽  
Body Condition ◽  
Protein Concentration ◽  
Post Partum ◽  
Live Weight ◽  
Group A ◽  
Time Of Infection ◽  
Native Pastures ◽  
Group 2 ◽  
Group 1

AbstractThis experiment studied the effects of body condition, long- and short-term levels of nutrition and trypanosomosis infection on the productivity of N’Dama cows using a 2 x 2 × 2 factorial cross-over design. Pre-partum, 23 cows received supplements for 6 months (H), the other group of 20 for 2 months (L). Both groups grazed native pastures. Two days post partum, half the cows from each group were placed on a basal (B) or supplemented (S) plane of nutrition. The diet of concentrate, groundnut hay and andropogon hay was the same, only the quantities differed. Four weeks post partum half the animals in each group were inoculated with T. congolense organisms (I), the others acted as controls (C). The trial continued for a further 6 weeks.Pre-partum nutrition (H, L had no effect on dry-matter intake (DMI) but pre-partum feeding (H) improved post-partum productivity, evident by higher dam live weights (P < 0·05), body condition (P < 0·001), calf birth weight (P < 0·05) and calf live-weight gain (P < 0·01). Post-partum nutrition had no effect on productivity. Trypanosomosis infection caused a reduction (P < 0·05) in total DMI. The decline in groundnut hay and concentrate intake was proportionally (P < 0·001) greater in the S-I group than in the B-I group. A low plane of nutrition pre-partum depressed milk yield but increased fat concentration (P < 0·05). Infection significantly reduced milk offtake (P < 0·05). The reduction in milk offtake (P < 0·01) and calf live weight (P < 0·05) were proportionally larger in the B-I than in the S-I group. Infection caused a decline in milk protein concentration (P < 0·05) and protein yield (P < 0·01) which was independent of dietary effects. Infection reduced (P < 0·01) the packed-cell volume but there were no interactions with diet. None of the cows was pregnant 150 days post partum but seven were cycling, 3(5) in the H-S-I group, 2(7) in the H-B-I group, 1(5) in the L-B-I group and 1(5) in the L-S-C group. These results suggest that S-I cows attempted to maintain milk yield at the expense of live weight whereas the B-I cows had insufficient live-weight reserves that could be mobilized. This suggests the nutritional balance and changes in weight at the time of infection might be more important than historical planes of nutrition.

The effect of plane of nutrition in early lactation on the performance of beef cows

1979 ◽  
Vol 29 (3) ◽  
pp. 293-303 ◽  
Author(s):  
B. G. Lowman ◽  
R. A. Edwards ◽  
S. H. Somerville ◽  
G. M. Jolly
Keyword(s):  
Weight Loss ◽  
Milk Yield ◽  
Crude Protein ◽  
Post Partum ◽  
Live Weight ◽  
Beef Cows ◽  
Metabolizable Energy ◽  
Yield Response ◽  
Mating Period ◽  
Digestible Crude Protein

ABSTRACTTwenty-one mature autumn-calving Blue Grey cows were divided into three groups for a 3-year change-over experiment, and each group was allocated to one of three planes of nutrition for the first 150 days of lactation during each year. Milk yields were recorded by machine milking twice daily. The three planes of nutrition corresponded to 1·63, 1·21 and 0·89 of the cow's maintenance allowance 12 h post partum. Increasing the plane of nutrition significantly (P<0·05) increased 150-day cumulative milk yield, but had no significant effect on milk composition. The extent of live-weight loss decreased significantly (P<0·001) as plane of nutrition increased and was reflected in cows maintaining better condition, measured as condition score, through the experimental period.The small 150-day cumulative milk yield response (32·8 kg per additional 10 MJ metabolizable energy and 62 g digestible crude protein/day) demonstrated the limitation of feeding beef cows for increased milk production in comparison with feeding the calf directly. However, the possible relationship between plane of nutrition, live-weight loss and fertility suggests an important limitation of under-feeding cows during the mating period. Within the constraints imposed, the medium treatment (64 MJ metabolizable energy and 516 g digestible crude protein/day) resulted in levels of cow performance similar to those currently recorded in commercial units. One of the major constraints in the present investigation was the high level of body reserves available in the cows at the start of lactation.

scholarly journals Lactation curves and persistency of White Fulani and Sokoto Gudali lactating cows

2020 ◽  
Vol 44 (4) ◽  
pp. 29-37
Author(s):  
O. E. Odegbile ◽  
I. I. Adedibu ◽  
C. Alphonsus
Keyword(s):  
Milk Yield ◽  
Preliminary Analysis ◽  
Post Partum ◽  
Prediction Equation ◽  
Coefficient Of Determination ◽  
Lactation Period ◽  
Lactating Cows ◽  
Lactation Curve ◽  
Breeding Programmes ◽  
White Fulani

The aim of this study was to determine the lactation curve traits of White Fulani (WF) and Sokoto Gudali (SG) lactating cows. Wood's gamma and Wilmink's curve parameters were employed to identify the lactation curve types and values for the parameters beginning yield (a) , coefficient of rising (b), coefficient of decreasing (c)t=timeande= is the exponential.The parameter assumed a fixed value derived from a preliminary analysis and disassociated with the time at peak yield were used to determine the shape and type of lactation curve. All Parameters in a typical lactation curves were positive, and in the event of one parameter being negative, the curve was considered to be an atypical lactation curve. Lactation records from WF (n=96)and SG (n=130) cows were recorded in the study area between year 2016-2017. Cows were hand-milked twice per day in the morning and evening from the 5 day post-partum till the end of the lactation period (260-270 days).Prediction equation of milk yield showed R values ranging from (32.00) in the SG to (35.00) in the WF. It was observed that the Wood's model curves were typical while Wilmink's model curves were atypical respectively. For typical lactation curves, a, b, c, persistency (S), time after parturition until the peak yield occurs (T ), maximum daily peak yield (Y ), and coefficient of determination (R ) were - 0.25±0.13, 1.08±0.07, 0.23±0.19, 2.34,51.00,2.62 and 97 for WF lactating cows and - 0.23 ± 0.14,1.13 ± 0.08, 0.07± 0.03, 2.33, 51.26, 2.58 and 96 for SG Lactating cows respectively. Parameters predicted by the Wood's model have the potential of being useful for breeding programmes in the SG and WF cows.  

197 The use of photostimulation to enhance oocyte cytoplasmic maturation

2020 ◽  
Vol 32 (2) ◽  
pp. 227
Author(s):  
C. M. Checura ◽  
S. L. Pratt ◽  
L. V. Campbell ◽  
K. Farmer ◽  
G. Loughlin ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Repeated Measures ◽  
Fixed Effects ◽  
Culture Medium ◽  
Near Infrared ◽  
Random Effect ◽  
Monochromatic Light ◽  
High Humidity ◽  
Stage Of Development ◽  
Cytoplasmic Maturation

Phototherapy uses monochromatic light from low-power lasers and light-emitting diodes (LEDs) to modulate biological processes. It has been proposed that the red-to-near infrared optical region (~600-1000nm) enhances cellular metabolic activity by activation of the mitochondrial respiratory chain. However, photostimulation induces the generation of oxide free radicals and could create oxidative stress in exposed cells. The main objective was to use photostimulation to affect the cumulus-oocyte complex metabolic state, aiming to enhance cytoplasmic maturation rates and subsequent embryonic development. A secondary objective was to determine the toxicity of the proposed photostimulation protocol. Abattoir-derived ovaries were used. All media was from IVF Biosciences (Falmouth, Cornwall, UK). Follicles 2 to 6mm in diameter were aspirated. Oocytes with compact cumulus and homogeneous cytoplasm were selected, and 50 oocytes/well were placed in invitro maturation medium (0h) and incubated at 38.5°C in 5% CO2 in air with high humidity in the presence (treatment=exposure for 2min to super-bright LED 1 and 2h after the beginning of maturation; LED wavelength of 660-665 nm; NTE30041; NTE Electronics Inc.) or absence (Control) of light. After maturation (22h), oocytes were split into two wells (25 oocytes/well) and subjected to IVF with semen from two different bulls for 18 to 20h. Cumulus cells were separated by vortexing, zygotes were placed in invitro culture medium, and incubated at 38.5°C in 5% CO2 in air with high humidity. Culture medium was renewed every 48h. Cleavage, morula, and blastocyst rates were recorded as a percentage of the number of oocytes subjected to IVF per treatment. The experiment was replicated 4 times. Statistical analysis was conducted using the Mixed procedure (SAS 9.4, SAS Institute Inc.) with repeated-measures and autoregressive covariance. The model's random effect was well within treatment. Fixed effects were bull, stage of development, and treatment. There was no difference (P=0.8) between treatments for any stage of development measured (cleavage: 76.4±2.7 vs. 74.8±4.1; morula: 36.1±4.8 vs. 35.9±5.8; blastocyst: 20.8±3.2 vs. 20.6±4.4 for control and treatment respectively; mean±s.e.). Sire affected development: bull 1 had a greater percentage (P&lt;0.05) cleavage (82.9±0.02 vs. 68.3±0.02), morula (42.6±0.05 vs. 29.4±0.04), and blastocyst (27.8±0.04 vs. 13.6±0.01) development than bull 2. There was no treatment×bull interaction (P=0.9). In conclusion, there were no stimulatory or toxic effects of this preliminary photostimulation protocol. Further research is needed to develop an optimal protocol that shows a metabolic effect and, potentially, an enhancement of invitro cytoplasmic maturation rates and subsequent embryonic development.

Effect of pre and post-natal nutrition on the performances of ewes and lambs under semi intensive rearing system

2020 ◽  
Vol 26 (1-2) ◽  
pp. 43-50
Author(s):  
S Ahmed ◽  
MRH Rakib ◽  
M Yesmin ◽  
M Ershaduzamman
Keyword(s):  
Body Weight ◽  
Weight Gain ◽  
Milk Yield ◽  
Post Partum ◽  
Live Weight ◽  
Daily Weight Gain ◽  
Weaning Weight ◽  
Concentrate Mixture ◽  
Daily Milk Yield ◽  
Daily Milk

The study was conducted to know the effect of different levels of pre and post-natal nutrition on the performances of ewes and their lambs until 1 year of age and the profitable slaughter age of lambs under semi intensive system. Twenty eight (28) native Bengal ewes at 7 weeks of gestation were randomly assigned to four groups (T0, T1, T2, T3) and supplemented with a concentrate mixture at 0.0, 1.0, 1.5, 2.0% of their body weight respectively. Ewes were allowed to graze 8 hours daily. Creep mixture (20 g/lamb/day) was provided to lambs from 2 weeks age with an increment of 10 g/lamb/week. After weaning, 20 growing male lambs were selected and reared 01 year of age with concentrate mixture at 1.5% of their body weight and 8 hours grazing irrespective of treatment groups. Parameters like, ewe’s litter size, daily milk yield, post-partum heat and lamb’s birth weight, weaning weight, live weight at 06, 09 and 12 months were recorded. The data were analyzed in an ANOVA with CRD by using SPSS v. 20. The mean differences were tested by DMRT at a probability level of P<0.05. After weaning, the lamb growths were analyzed considering age as fixed factor. Regression correlations among different parameters with different ages were also performed. Significantly higher daily milk yield (P<0.01), weaning weight (P<0.05) and daily weight gain of lamb until weaning (P<0.05) were observed in T2 group. Besides, lambs weight at 06, 09, and 12 months differ significantly (P<0.01) along with corresponding daily weight gain (P<0.05). Lambs daily weight gain did not differ significantly from weaning to 09 months of age but significantly reduced (P<0.05) from 09 to 12months age. Finally, it may be concluded that a concentrate diet containing 20% CP during late pregnancy to lactation should be supplied to obtain maximum performances of ewes and their lambs. Besides, native Bengal lamb would be slaughtered between 06 to 09 months of age to get maximum return. Bang. J. Livs. Res. Vol. 26 (1&2), 2019: P. 43-50

The effect of dietary metabolizable energy concentration upon the pre- and post-weaning performance of growing rabbits

1983 ◽  
Vol 36 (2) ◽  
pp. 229-236 ◽  
Author(s):  
Catherine Butcher ◽  
M. J. Bryant ◽  
E. Owen ◽  
I. Leach ◽  
D. H. Machin
Keyword(s):  
Weight Gain ◽  
Milk Yield ◽  
Dry Matter ◽  
Post Partum ◽  
Live Weight ◽  
Metabolizable Energy ◽  
Energy Concentration ◽  
Adaptation Period ◽  
Live Weight Gain ◽  
Weight Gains

ABSTRACTTwenty-five Californian does were mated and given pelleted diets of either 8(LE) or 10(HE) MJ/kg dry matter (ruminant metabolizable energy values) throughout gestation and lactation. Litter sizes were adjusted to six offspring per doe. Milk yield was estimated from the weight differences of the litters before and after suckling, when the opportunity for nursing was confined to once daily. The young rabbits were allowed access to either the LE or HE diets from 18 days of age. Weaning took place at 32 days of age when four rabbits from each doe grouP × pre-weaning diet were slaughtered. Diet had no effect on litter size or birth weight, but does on the LE diet had lower live weights post partum (P < 0·05). Dry-matter consumption by the does on the LE diet was greater than for the HE diet (P < 0·05) both during gestation and lactation, but calculated metabolizable energy intakes were lower during lactation. There were no statistically significant differences between treatments for milk yield or live-weight gain to weaning and dry-matter intakes of the young at weaning, but daily live-weight gain from fostering to 18 days of age was greater for litters of does fed the HE rather than the LE diet (P < 0·05). There were no statistically significant differences between diets for carcass traits at weaning.After weaning, 32 rabbits were given either the LE or HE diet until 2 kg live weight when they were slaughtered. A post-weaning × pre-weaning diet interaction (P < 0·05) occurred for live weights of the rabbits at the start of the post-weaning trial (i.e. after a 10-day adaptation period) with LE: LE rabbits being lighter than other rabbits as a results of poor live-weight gains during the adaptation period. Live-weight gains to slaughter were greater for the pre-weaning LE diet (P < 0·05) and the post-weaning HE diet (P < 0·01), although dry-matter intakes of the HE diet were less (P < 0·05). Rabbits on the LE diet had greater empty gut weights (P < 0·05) and lighter livers (P < 0·05) at slaughter.

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