Effects of high and low levels of feeding with or without protected protein on the performance of lactating goats were studied. Twenty four German Fawn goats either from 1st (43.37±3.937 kg and 2 year old) or 3rd 62.64±6.783 kg and 4-5 year old) parity were used for the trial. Feeding levels were 7.2 (I) and 5.2 (II) MJ ME/litre of milk of 3.5% fat in addition to that of the maintenance allowance. At each feeding level, diet had either unprotected (U) or formaldehyde protected (P) soya-meal. Thus, four diets were IU, IP, IIU and IIP, having six animals in each. The diets were composed of hay and pellet (10:4:1 of beet pulp : barley : soya-meal). Effect of feeding level, protein protection, parity, health status and kid number on intake, milk yield, milk composition, growth rate of goats were recorded across the 21 weeks of study. High feeding level resulted increase (p<0.001) in estimated metabolizable energy (ME) and metabolizable protein (MP) availability. Dietary inclusion of protected soya-meal increased (p<0.001) the estimated MP but not the ME availability. Animals in 1st parity ate more (p<0.001) DM (111 vs. 102 g/kg W 0.75 /d) than those in 3rd parity. Animals with twin kids (110 g/kg W 0.75 /d) had higher (p<0.001) DM intake than those with single kid (102 g/kg W 0.75 /d). Fat (4%) corrected milk (FCM) yield was not effected by high (1,924 g/d) or low (1,927 g/d) feeding level but increased (p<0.001) with protected (2,166 g/d) compared with unprotected (1,703 g/d) soya-meal. FCM yield for four dietary combinations were 1,806, 2,078, 1,600 and 2,254 g/d for diets IU, IP, IIU and IIP, respectively. For unit increase (g) in estimated MP availability relative to ME (MJ) intake, FCM yield increased 1,418(±275.6) g daily (r 2 =0.58; p<0.001). Milk fat (3.14 vs. 3.54%; p<0.001) and protein (2.94 vs. 3.04% p<0.05) contents were lower at high than the low feeding level. Protected protein increased (p<0.001) the fat, lactose and net energy (NE) content of milk. Milk urea concentration of 175, 183, 192 and 204 mg/l for diets IU, IP, IIU and IIP, respectively indicated lower RDP content of these diets. The RDP contents were 6.97, 6.70, 7.30 and 6.83 g/MJ of ME for diets IU, IP, IIU and IIP, respectively. Live weight change over the experimental period were 41, 6, 17 and 19 g/d. Absence of any positive response of high feeding was probably due to inefficient rumen fermentation resulting from inadequate RDP supply. Protected protein improved production performance apparently by increasing MP:ME ratio in the absorbed nutrient.
SummaryTitle of the paper: Influence of energy level and dietary protein quality and quantity on the lactation performance of German Fawn Goats In this study two feeding trials were conducted using a total of 45 goats (German Fawn) to estimate milk yield for a lactation period of 150 days. Goats were fed corresponding German (high, H) and International (low, N) feeding standards for milk production. At each feeding level the diet had either protected (P, formaldehyde) or unprotected (U) Soya meal, resulting in different UDP amounts. The diets used in the trials had different protein contents: V1 low (11.9-12.3%) and V2 high (15.9-16.6%) respectively. The diet were composed of hay and pellets with energy contents ranging from 11.3 to 11.6 MJ ME/ kg DM. The milk yield was 40% lower in groups of V1 as compared to groups of V2 which is mainly attributed to the decreased energy and protein intake, partly caused due to low feed intake and the lack of RDP for optimal rumen microbial activity in V1. There also existed a strong correlation between feed intake and protein content of the diet. Feeding of protein protection resulted in an increased protein amount at duodenum and the goats gave a higher milk yield, provided a sufficient RDP level was secured A high protein content in diet (16%) at middle and late lactation induced a protein surplus which is combined with inefficient energy utilisation. During the lactation period the diets have to be adapted not only for energy but also for protein needs Key Words: lactating goats, feeding, requirements, protein protection, milk yield, ZusammenfassungIn zwei Versuchen standen insgesamt 45 laktierende Ziegen der Rasse Bunte Deutsche Edelziege über die ersten 150 Laktationstage für die Prüfung der Milchleistung zur Verfügung. Die Tiere erhielten entsprechend der deutschen und internationalen Normen für die Milchleistung ein hohes (H) bzw. niedriges (N) Energieangebot. Jede Gruppe wurde in zwei Untergruppen geteilt, die durch Gabe von ungeschütztem (U) bzw. geschütztem (P) Sojaextraktionsschrot unterschiedliche Anteile an im Pansen unabbaubarem Protein erhielten. Die beiden Versuche unterschieden sich durch einen niedrigen (11,9-12,3%) bzw. hohen (15,9 bis 16,6%) Rohproteingehalt der Ration. Die Diät bestand aus Wiesenheu und einem pelletierten Konzentratfutter mit veränderter Komponentenzusammensetzung, jedoch ausgeglichenem Energiegehalt (11,2 bis 11,6 MJ ME/ kg TS
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