Factores que afectan algunas características productivas y composición de leche de caprinos en condiciones tropicales
In order to study the effect of some non-genetic factors and breed group on milk production and its components and characteristics, prenatal and preweaning growth, and lactation curve of goats in tropical conditions, 218 lactations of 171 goats milked once a day, 384 birth weights (BW), 186 weaning...
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2013
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| Online Access: | http://hdl.handle.net/10872/4211 |
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| Summary: | In order to study the effect of some non-genetic factors and breed group on milk production and its components and characteristics, prenatal and preweaning growth, and lactation curve of goats in tropical conditions, 218 lactations of 171 goats milked once a day, 384 birth weights (BW), 186 weaning weights (BW), 758 milk samples and 46103 daily milk production were analyzed. Data correspond a period of nine years, from a multibred confined goat herd located in Maracay (10° 16' 25.30'' N and 67º 36' 35'' W). The total milk yield (TY), milk yield at 210 days (Y210), days in milk (DM), the components and characteristics of milk, BW, WW and lactation curve, were evaluated. Data were analyzed by a linear additive statistical model with sire as random effect and age at calving (EC), year (YC) and month of calving o birth (MC) of calving o birth, prolificacy (P), breed group (BG) and sex (S) only for BW and WW as a fix effects, and as covariates previous dry period (DP) and DM for milk yield. Phenotypic correlations (FC) between components and characteristics of milk by the Pearson method were estimated. Lactation curves comparing nine mathematical functions were estimated. All sources of variation but P (P> 0.05) affected (P <0.05) TY, all but MC and P (P> 0.05) affected (P <0.05) P210, DM was affected (P <0.05) by EC, YC and MC, but not by P, DP and BG. Means for TY, Y210 and DM were 195.23 kg, 156.76 kg and 239.24 days, respectively. The BG 1/2Canary1/2Alpine French had the highest PT, P210d and DL with a maximum difference between BG of 53.74, 51.55 kg and 34.47 days, respectively. Pure and 5/8 Canary goats had a tendency to have shorter lactations. The TY, Y210 and DM increased with each level of EC up to six years of age, with a maximum difference of 75.15, 86.38 kg and 67 days, respectively. The biggest difference among YC for TY, Y210 and DM was 134.34, 144.27 kg and 72.6 days, respectively, and these variables declined over the years. The maximum difference among MC was 72.6 and 33.4 kg 100.43 days, for TY, Y210 and DM, respectively. Goats that calved in September had higher TY, and DM. The mean of DM was 131.15 days. For every additional DM day over the average, the TY and Y210 had a reduction of 0.18 kg and 0.14 kg, respectively. The DP did not affect DM (P = 0.36). The DM had an average of 239.24 days, and for each additional day, the TY increased 0.72 kg. The mean BW and WW was 2.62 and 10.73 kg respectively. The BW was affected by BG, EC, S and P (P< 0.05), but not by YC and MC (P> 0.05). The WW was affected by MC, S, and P (P< 0.05) and BG, EC, and YC did not affect. The pure and >5/8 Alpine French were heavier at birth (2.91 ± 0.10 kg), being different (P <0.05) of the other BG and with a tendency of this group to present higher WW. The means of the characteristics and components (%) of goat milk were cryoscopy (° C) -0.56, acidity (0.1 mL NaOH N/100 milk mL) 19.12, chlorides (%) 0.22 , WMT (mm) 10.75 pH 6.55, 4.32 fat, 4.00 protein, 2.63 casein, 86.69 humidity, total solids (TS) 13.30 nonfat solids (NFS) 9.04, ash 0.77 and 4.27 lactose. All the fixed effects studied affected in variable form the characteristics and components of milk. Cryoscopy was correlated with acidity and mastitis, -0.05 (P = 0.37), -0.30 (P <0.05) respectively, but with pH was 0.34 (P <.001). The FC of acidity with pH was -0.14 (P <.001). There was a FC between fat and all other components of milk, 0.36, 0.12, 0.41, 0.78, (P <.001), with protein, ash, casein, and TS, respectively, except with humidity, chlorides and lactose with which have a FC of -0.77, -0.20, -0.12 (P <.001). Protein showed a FC with humidity, ash, casein, TS, NFS and lactose of -0.49, 0.18, 0.55, 0.49, 0.36, -0.26, (P <.001), respectively. The TS had a FC with nonfat solids of 0.61 and with humidity of -0.99 (P <.001). The NFS had a FC with humidity FC -0.61 (P <.001). The ash had FC with fat, protein, casein, TC and chlorides of 0.12, 0.18, 0.15, 0.14, 0.21 (P <.001), respectively, and negative FC with humidity and lactose, -0.13, -0.17 (P <.001). The chlorides had a FC of 0.21 (P <.001) with ash and a variable FC with all other components. Wood was the model that best described the lactation curve in goats by having a high coefficient of determination and the minimum mean square error, with differences in the curves by this model in each of the fixed factors included in the model. It can be expected differences between breed groups and non-genetic factors in PT, P210, DL, PN, PD, components and characteristics of milk as well as the shape of the lactation curve of goats in tropical conditions. The GR 1/2Canaria1/2Alpina highlighted over all other genotypes. |
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